Integrated isolator and circulator system

Abstract

The invention discloses an integrated photonic system comprising an integrated polarization device for implementing an on-chip opto-isolator and a circulator. An integrated photonic component implemented around a Faraday rotator isolator arrangement is arranged in the apparatus to polarize and rotate the polarization of an optical signal passing forward and backward through the apparatus to implement an optoisolator and circulator.

Description

Technical Field

[0001] The present invention relates to photonic systems, and in particular, to on-chip isolators and circulators for use in photonic systems incorporating integrated photonics for isolating and directing optical signals. Summary of the invention

[0002] According to a first aspect, an integrated photonic system is provided, which includes: at least one integrated chip; a first integrated polarization device integrated in the at least one integrated chip, used to transmit a first incident light signal received through a first component side port of the first integrated polarization device as a first polarized light signal into free space through a polarization side port of the first integrated polarization device; and at least one Faraday rotator, which is used to receive the first polarized light signal, rotate the polarization of the first polarized light signal and generate a rotated first polarized light signal propagating along a first direction; and to receive a second polarized light signal having the same polarization as the rotated first polarized light signal and propagating in a second direction opposite to the first direction, rotate the polarization of the second polarized light signal and generate a rotated second polarized light signal; wherein the first integrated polarization device is constructed to receive the rotated second polarized light signal through the polarization side port of the first integrated polarization device, and guide the rotated second polarized light signal away from the first component side port of the first integrated polarization device.

[0003] Some embodiments also include a second integrated polarization device integrated in the at least one integrated chip, which is used to transmit the rotated first polarization light signal received through the polarization side port of the second integrated polarization device as an output light signal through the component side port of the second integrated polarization device, and to transmit the second incident light signal received through the component side port as the second polarization light signal through the polarization side port toward the at least one Faraday rotator into free space.

[0004] In some embodiments, the at least one Faraday rotator includes a first 45° Faraday rotator and a second 45° Faraday rotator, the first integrated polarization device includes a first polarization beam splitter rotator (PSR), and the second integrated polarization device includes a second PSR, and the integrated photonic system also includes: a first lens between the first PSR and the at least one Faraday rotator, for collimating the first polarized light signal; a polarizer between the first 45° Faraday rotator and the second 45° Faraday rotator, which is oriented at 45° relative to the polarization of the first polarized light signal in the same rotation direction as the rotation applied by the first 45° Faraday rotator; and a second lens between the at least one Faraday rotator and the second PSR, for converging the rotated first polarized light signal.

[0005] In some embodiments, the at least one Faraday rotator includes a 45° Faraday rotator, and the second integrated polarization device includes an integrated polarization controller (IPC) for generating the output optical signal having a polarization different from the polarization of the rotated first polarized optical signal, and for generating the second polarized optical signal from the second incident optical signal, the second incident optical signal having the same polarization as the output optical signal.

[0006] In some embodiments, the first integrated polarization device is configured to substantially discard the rotated second polarization light signal received by the first integrated polarization device.

[0007] In some embodiments, the first integrated polarization device is configured to direct the rotated second polarization optical signal received by the first integrated polarization device substantially through a second component-side port of the first integrated polarization device.

[0008] In some embodiments, the IPC includes: a polarization side port facing the 45° Faraday rotator; at least one component side port opposite to the polarization side port of the IPC; a polarization beam splitter rotator PSR, which includes a first port, a second port and a third port, and the PSR is coupled via the first port of the PSR through the polarization side port of the IPC; a first group of waveguides coupled to the second port and the third port of the PSR; a first phase shifter coupled along a first waveguide in the first group of waveguides; and a first beam splitter including a first group of ports and a second group of ports, and the first beam splitter is coupled to the PSR through the first group of waveguides and via the first group of ports of the first beam splitter, and is coupled via the at least one component side port of the IPC through at least one port of the second group of ports of the first beam splitter.

[0009] Some embodiments further include a lens between the first integrated polarization device and the 45° Faraday rotator.

[0010] In some embodiments, the first integrated polarization device is one of a plurality of first integrated polarization devices included in the integrated photonic system, wherein the IPC is one of a plurality of IPCs included in the integrated photonic system, and wherein the 45° Faraday rotator comprises a shared 45° Faraday rotator for rotating the polarization of optical signals transmitted between the plurality of first integrated polarization devices and the plurality of IPCs.

[0011] Some embodiments further provide a lens array between the plurality of first integrated polarization devices and the common 45° Faraday rotator.

[0012] Some embodiments further provide a single common lens between the plurality of first integrated polarization devices and the common 45° Faraday rotator.

[0013] In some embodiments, each of the plurality of first integrated polarizers and each of the plurality of IPCs are angled relative to the focal plane of the single common lens, and the at least one integrated chip includes a curved surface proximate to a location where the first integrated polarizer and IPC are integrated.

[0014] In some embodiments, the at least one Faraday rotator includes a 22.5° Faraday rotator, and the integrated photonic system further includes: a lens between the first integrated polarization device and the 22.5° Faraday rotator; and a reflector located on the opposite side of the 22.5° Faraday rotator from the lens, for reflecting the optical signal passing through the 22.5° Faraday rotator from the lens back into the 22.5° Faraday rotator toward the lens; wherein the second integrated polarization device includes an integrated polarization controller (IPC) for generating the output optical signal having a polarization different from the polarization of the rotated first polarized optical signal, and for generating the second polarized optical signal from the second incident optical signal, the second incident optical signal having the same polarization as the output optical signal.

[0015] In some embodiments, the IPC includes: a polarization side port facing the 22.5° Faraday rotator; at least one component side port opposite to the polarization side port of the IPC; a polarization beam splitter rotator PSR, which includes a first port, a second port and a third port, and the PSR is coupled via the first port of the PSR through the polarization side port of the IPC; a first group of waveguides coupled to the second port and the third port of the PSR; a first phase shifter coupled along a first waveguide in the first group of waveguides; and a first beam splitter including a first group of ports and a second group of ports, and the first beam splitter is coupled to the PSR through the first group of waveguides and via the first group of ports of the first beam splitter, and is coupled via the at least one component side port of the IPC through at least one port of the second group of ports of the first beam splitter.

[0016] In some embodiments, the first integrated polarization device is one of a plurality of first integrated polarization devices included in the integrated photonic system, wherein the IPC is one of a plurality of IPCs included in the integrated photonic system, and wherein the 22.5° Faraday rotator includes a shared 22.5° Faraday rotator for rotating the polarization of optical signals transmitted between the plurality of first integrated polarization devices and the plurality of IPCs.

[0017] In some embodiments, the lens includes a single common lens between the plurality of first integrated polarizers and the common 22.5° Faraday rotator, and wherein each of the plurality of first integrated polarizers and each of the plurality of IPCs are angled relative to a focal plane of the single common lens, and the at least one integrated chip includes a curved surface proximate a location where the first integrated polarizer and the IPC are integrated.

[0018] In some embodiments, the lens, the reflector, and the 22.5° Faraday rotator are combined together to form a single lens-rotator-reflector assembly.

[0019] In some embodiments, the lens-rotator-reflector assembly is mounted on one or more of the at least one integrated chip, or on a common substrate on which the at least one integrated chip is mounted.

[0020] In some embodiments, the at least one Faraday rotator includes a 22.5° Faraday rotator, and the integrated photonic system further includes: a lens between the first integrated polarization device and the 22.5° Faraday rotator; and a reflector located on the opposite side of the 22.5° Faraday rotator from the lens, for reflecting the optical signal that passes through the 22.5° Faraday rotator from the lens back toward the lens into the 22.5° Faraday rotator; wherein the first integrated polarization device includes an IPC for generating the first polarized optical signal having a polarization different from the polarization of the first incident optical signal.

[0021] In some embodiments, the IPC is configured to substantially discard the rotated second polarization optical signal received by the IPC.

[0022] In some embodiments, the IPC is configured to direct the rotated second polarization optical signal received by the IPC substantially through a second component-side port of the IPC.

[0023] The above and additional aspects and embodiments of the present invention will be apparent to those skilled in the art based on the detailed description of various embodiments and / or aspects with reference to the accompanying drawings, and a brief description of the drawings is provided below. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other advantages of the present invention will become apparent upon reading the following detailed description and referring to the accompanying drawings.

[0025] FIG. 1 is a schematic block diagram of a known fiber isolator.

[0026] Figure 2 is a schematic diagram of a double-stage integrated photonics isolator according to an embodiment.

[0027] Figure 3 is a schematic diagram of a single-stage integrated photonic isolator according to an embodiment.

[0028] Figure 4 is a schematic block diagram of a system including a type I integrated polarization controller (IPC) having a single component-side port according to an embodiment.

[0029] Figure 5 is a schematic block diagram of a system including a Type I IPC having two component-side ports according to an embodiment.

[0030] Figure 6is a schematic block diagram of a system including a Type II IPC having a single component-side port according to an embodiment.

[0031] Figure 7 is a schematic block diagram of a system including a Type II IPC having two component-side ports according to an embodiment.

[0032] Figure 8 is a schematic block diagram of a system including a controllable Type II IPC with a single component-side port and feedback according to an embodiment.

[0033] Fig. 9 is a schematic diagram of a single-stage integrated photonics circulator including an IPC according to an embodiment.

[0034] Fig.10 is a schematic diagram of a single-stage, single-lens integrated photon circulator or isolator device including an IPC according to an embodiment.

[0035] Fig.11 is a schematic diagram of a multi-beam array, single-stage, single-lens integrated photon circulator or isolator device including an IPC according to an embodiment.

[0036] Fig.12 is a schematic diagram of a multi-channel, single-stage, single-lens integrated photonic circulator or isolator device including an IPC according to an embodiment.

[0037] Fig.13 is a schematic diagram of a reflective single-stage, single-lens integrated photon circulator or isolator device including an IPC according to an embodiment.

[0038] Fig.14 is a schematic diagram of a reflective single-stage integrated photonic circulator or isolator device incorporating an IPC and including a joined lens, rotator, and reflector assembly according to an embodiment.

[0039] Fig.15 is a schematic diagram of a multi-channel, single-stage integrated photonic circulator or isolator device incorporating an IPC and including joined lens, rotator, and reflector assemblies according to an embodiment.

[0040] Fig.16 is a schematic diagram of a single-stage integrated photon circulator or isolator device incorporating an IPC and including separate lenses, rotators, and reflectors according to an embodiment.

[0041] Fig.17 is a schematic diagram of an on-chip assembly of an integrated circulator or isolator device with bonded lens, rotator, reflector assemblies according to an embodiment.

[0042] Fig.18is a schematic diagram of an on-chip assembly of an integrated circulator or isolator device with bonded lens, rotator, reflector assemblies according to an embodiment including a common substrate.

[0043] Fig.19 is a schematic diagram of an integrated photonic circulator or isolator device including a single IPC according to an embodiment.

[0044] Although the present invention is susceptible to various modifications and alternative forms, specific embodiments or implementations have been shown by way of example in the accompanying drawings and will be described in detail herein. However, it should be understood that the present invention is not intended to be limited to the specific forms disclosed. On the contrary, the present invention will cover all modifications, equivalents and alternatives that fall within the scope of the invention defined by the appended claims. DETAILED DESCRIPTION

[0045] Photonic systems use many structural and functional elements to guide, transmit, manipulate or otherwise use photonic signals in their desired applications. In many such systems, the guidance of optical signals is implemented in the form of circulators and sometimes in the form of isolators. In light detection and ranging (LIDAR) systems, a 2x2 transmit / receive beam splitter will produce a round-trip loss of 6dB. This is not a trivial or insignificant power loss due to the light beams emitted toward and received from the target object. The greater the power associated with the optical signal used in the detection and ranging of the target object, the more accurate and possibly larger the upper range of the lidar instrument. A moderately lossy circulator (about 1dB loss per pass) will provide a 4dB link-budget improvement, which is not insignificant. Better performing circulators can push this improvement even higher.

[0046] Typically, circulators include the required magneto-optical materials, however, there is no known good integration method at wafer level. In addition, conventional (fiber) isolators / circulators are very large and expensive, and they require fiber alignment. Non-magnetic isolators have been demonstrated, but the loss / isolation performance is very poor.

[0047] In modern silicon photonics, integrating as much structure and functionality as possible into on-chip devices offers advantages over free-space components, including size, cost, and optimization of optical performance, to name a few. Whether in LiDAR or any other optoelectronic application, optical circulators and isolators can be complex and / or bulky, sometimes involving multiple beamsplitting cubes, large birefringent crystals or wave plates, etc., and converting back and forth between on-chip polarization optics and free-space polarization optics can introduce unwanted insertion losses.

[0048] The present disclosure describes on-chip solutions for optical isolators and circulators that include integrated polarization controllers for converting, controlling, and utilizing the polarization state of light, avoiding or mitigating the problems associated with optical solutions consisting solely of free-space optics. Isolators and circulators are used in a wide range of photonics applications, many of which can benefit from the solutions disclosed herein.

[0049] 1 , a known fiber optic isolator 100 based on a dual-stage isolator design will now be discussed.

[0050] The optical signal passing through the first optical fiber or waveguide 111 is launched into free space via, for example, a transmitter or a coupler, after which the optical signal is collimated by the first converging lens 102a. The collimated optical signal encounters the front side of the double-stage isolator 150, which includes a first polarizer 151 oriented at a first angle (e.g., 0°) to the x-axis. Almost all optical signals passing through the first polarizer 151 appear 0° polarized, and then pass through a first Faraday rotator 155a that rotates the polarization of the optical signal by 45°, generating a polarized optical signal that is mainly 45°. The optical signal encounters a second polarizer 152 arranged to have a 45° orientation relative to the first polarizer 151 (e.g., 45° orientation to the x-axis). Almost all optical signals pass through the second polarizer 152, and the portion that is not 45° polarized is further reduced. Afterwards, the optical signal passes through a second Faraday rotator 155b that further rotates the optical signal by 45°, generating a polarized optical signal that is mainly 90°. The generated 90° polarized optical signal encounters a third polarizer 153 arranged to have a 45° orientation (e.g., 90° to the x-axis) relative to the second polarizer 152. Almost all of the optical signal passes through the third polarizer 153, and the small portion that is not 90° polarized is further reduced. Afterwards, the optical signal is converged when passing through the second converging lens 102b, and then collected at the second optical fiber or waveguide 112 via a coupler or a transmitter.

[0051] Due to the operation of the Faraday rotators 155a, 155b and the arrangement of the first, second and third polarizers 151, 152, 153, any optical signal travelling in the other direction (ie from the second optical fiber or waveguide 112 towards the first optical fiber or waveguide 111) is substantially blocked.

[0052] Any optical signal passing through the second optical fiber or waveguide 112 is launched into free space and collimated via the second converging lens 102b. The collimated optical signal encounters the double-stage isolator 150 from the rear side, and first interacts with the third polarizer 153 oriented at a third angle of 90°. Almost all optical signals passing through the third polarizer 153 appear 90° polarized, and then pass through the second Faraday rotator 155b that rotates the optical signal by 45°, generating a polarized optical signal that is mainly 135°. The generated polarized optical signal that is mainly 135° encounters the second polarizer 152 arranged to have a 45° orientation. Therefore, almost all optical signals are blocked by the second polarizer 152 because the polarization of the optical signal is orthogonal to the orientation of the second polarizer. Any portion of the optical signal from the second optical fiber or waveguide 112 that was initially at 0° and not completely blocked by the third polarizer 153 obtains 45° in the second Faraday rotator 155b, passes through the second polarizer 152 oriented at 45°, and then obtains 45° again to achieve a polarization of 90°, at which point it encounters the first polarizer 151 oriented at 0°, and the first polarizer 151 substantially blocks that portion.

[0053] It should be understood that a dual stage isolator, as well as any single or multi-stage isolator based on a similar design, operates by utilizing a known rotation angle imposed on the polarization of an optical signal passing through a fixed length Faraday rotator, and arranging the orientation of the polarizer set to transmit optical signals traveling in one direction along the isolator while blocking optical signals traveling in the opposite direction.

[0054] It should be noted that the single stage isolator variation of the isolator of FIG. 1 utilizes only two polarizers oriented at a 45° relative angle and separated by a Faraday rotator that applies a 45° rotation.

[0055] It should be noted that although in principle the dual-stage isolator can be oriented at any angle, only one polarization orientation will be fully transmitted in the forward direction of the isolator. Thus, depending on the rotation of the fiber, only a single polarization along the slow or fast axis can be effectively supported for transmission and isolation.

[0056] To implement isolators in an integrated environment to avoid or mitigate the issues associated with optical solutions consisting of free-space components, such as Figure 2 The integrated photonic isolator 200 is shown with polarizers placed before and after the double-stage isolator.

[0057] It should be noted that some optical devices, particularly integrated polarization devices such as polarization beam splitters (PSRs) and integrated polarization controllers (IPCs) described below, may be described with optical signals traveling in either direction or in both directions simultaneously. In the particular context of devices characterized by polarized optical signals having orthogonal components on one side, and components of polarized optical signals (in the form of linearly polarized signals) on the other side, rather than structurally describing any of the various device ports as inputs or outputs, it may be useful to describe certain aspects of the devices and structures as a "polarization side" or "component side." As will become clear below, a "polarization side" will refer to the side or direction of a device that receives or transmits polarized optical signals, and a "component side" will refer to the side or direction of a device that receives or transmits components of polarized optical signals (in the form of linearly polarized signals).

[0058] Regarding the structure, the first integrated optical chip 201a (other waveguides and internal devices are not shown) includes a first PSR 220a.

[0059] The PSR includes three ports: a single polarization side port and a first component side port and a second component side port. The polarization side port and the first component side port form a first path through the PSR, while the polarization side port and the second component side port form a second path through the PSR. The orthogonal components of the optical signal passing through the PSR from the polarization side are split and output on two independent component side ports, one component passes through the first path without rotation, and the other component undergoes a 90° rotation of polarization when passing through the second path. Therefore, the PSR can be described as having an orientation defined by the direction of this preferred polarization angle, that is, one can define the "polarization" of the first path based on the polarization of the optical component, which can pass through the first path without any polarization rotation or reorientation.

[0060] The first PSR 220a is coupled to the rest of the first integrated optical chip 201a via its first component side port, and is coupled to free space on its polarization side port via, for example, a transmitter or a coupler (not shown). In some embodiments, the second component side port of the first PSR 220a is further coupled to the first integrated optical chip 201a in a manner such that the optical signal emitted from the first PSR 220a on the second component side port is discarded by termination of the output, for example, using a adapter or doping. The first PSR 220a is arranged so that the polarization of its first path is along, for example, the x-axis (E xor TE) direction or 0° orientation. The first converging lens 202a is located between the first integrated optical chip 201a and the double-stage isolator 250, which includes a first Faraday rotator 255a for applying a 45° rotation, which is coupled to a polarizer 252 oriented at 45°, and the polarizer 252 itself is coupled to a second Faraday rotator 255b for applying a further 45° rotation. The second converging lens 202b is arranged between the double-stage isolator 250 and the second integrated optical chip 201b, and the second integrated optical chip 201b includes a second PSR 220b, which is also coupled to free space via an emitter or coupler (not shown). The second PSR 220b is coupled to the emitter or coupler via its polarization side port, and is coupled to the rest of the second integrated optical chip 201b via its second component side port. The second PSR 220b is arranged so that the polarization of its first path is along, for example, the x-axis (E x In some embodiments, the first component side port of the second PSR 220b is further coupled to the second integrated optical chip 201b in such a manner that the optical signal emitted from the second PSR 220b on the first component side port is discarded.

[0061] Regarding the function, the first PSR 220a receives a TE optical signal on its first component side port through a waveguide within the first integrated optoelectronic chip 201a. The optical signal passes through the first path of the first PSR 220a and is emitted from the first PSR 220a to free space through an associated transmitter or coupler. The optical signal is collimated by the first converging lens 202a, after which the optical signal encounters the double-stage isolator 250. The 0° TE optical signal passes through the first Faraday rotator 255a, which rotates the polarization of the optical signal by 45°, to produce a polarized optical signal that is mainly 45°. The polarized optical signal that is mainly 45° encounters the polarizer 252, which is arranged to have an orientation of 45° relative to the polarization produced by the first PSR 220a, that is, an orientation of 45°. Almost all of the optical signal passes through the polarizer 252, and any portion that is not polarized at 45° will be attenuated. Afterwards, the optical signal passes through the second Faraday rotator 255b, which further rotates the polarization of the optical signal by 45°, thereby generating an optical signal with a polarization of mainly 90°. y The polarized optical signal of TE or TM) leaves the double-stage isolator 250, is converged by the second converging lens 202b, and is then collected at a coupler or transmitter associated with the second PSR 220b. The TM optical signal enters the polarization side port of the second PSR 220b, passes through the second path where it is rotated into a TE optical signal, and is output on the second component side port of the second PSR 220b to enter the second integrated optical chip 201b.

[0062] Due to the operation of the Faraday rotators 255a, 255b and the arrangement of the first and second PSRs 220a, 220b and the polarizer 252, any TE polarized optical signal traveling in other directions (ie, from the second PSR 220b toward the first PSR 220a111) within the second integrated optical chip 201b is substantially blocked.

[0063] The optical signal with TE polarization inputted at the second component side port and passing through the second path of the second PSR 220b is used as the TM signal (E y or 90°) is launched into free space and collimated via the second converging lens 202b. The collimated optical signal encounters the double-stage isolator 250 from the rear side, passes through the second Faraday rotator 255b that rotates the polarization of the optical signal by 45°, and produces a polarized optical signal that is mainly 135°. The polarized optical signal that is mainly 135° encounters the polarizer 252 oriented at 45°. Therefore, almost all of the optical signal is blocked by the polarizer 252 because the polarization of the optical signal is orthogonal to the orientation of the polarizer. Any portion of the stray TE optical signal from the second PSR 220b obtains 45° in the second Faraday rotator 255b, passes through the polarizer 252 oriented at 45°, and then obtains 45° again to achieve TM (90°) polarization, at which point it encounters the first PSR 220a, which essentially guides the portion away from its first path and guides the portion to its second component side port through its second path to discard the portion.

[0064] although Figure 2 and the following Figure 3 and Figure 9-12 The embodiments shown in are described as including a first integrated optical chip and a second integrated optical chip, but it should be understood that, in general, the first and second integrated optical chips can be separate integrated optical chips (which may or may not be integrated on a common substrate), or can be two parts of the same integrated optical chip in which any lenses, polarizers or Faraday rotators are arranged, separated by, for example, a recess or an etched cavity formed in the integrated optical chip.

[0065] To implement isolators in an integrated environment to further avoid or mitigate the issues associated with optical solutions consisting of free-space components, such as Figure 3 The illustrated integrated photonic isolator 300 completely eliminates the double-stage isolator and all polarizers and adopts a single-stage Faraday rotator design.

[0066] Regarding the structure, the first integrated optical chip 301a (other waveguides and internal devices are not shown) includes a polarization beam splitter rotator PSR 320. PSR 320 is coupled to the rest of the first integrated optical chip 301a via its first component side port, and is coupled to free space on its polarization side port via, for example, a transmitter or coupler (not shown). In some embodiments, the second component side port of PSR 320 is coupled to the first integrated optical chip 301a in a manner that discards the optical signal emitted from PSR 320 on the second component side port. PSR 320 is arranged so that the polarization of its first path is along, for example, the x-axis (E x The first converging lens 302a is between the first integrated optical chip 301a and the single-stage isolator, which includes a Faraday rotator 355 for applying a 45° rotation. The second converging lens 302b is arranged between the Faraday rotator 355 and the second integrated optical chip 301b, which includes an integrated polarization controller (IPC) 330, such as similar to the one described below in conjunction with Figure 4 , Figure 5 , Figure 6 , Figure 7 or Figure 8 The IPC 330 is coupled to a transmitter or coupler (not shown) via its polarization side port and to the rest of the second integrated optical chip 301b via one of its component side ports.

[0067] Regarding function, PSR 320 receives a TE optical signal passing through a waveguide within a first integrated optoelectronic chip 301a on its first component side port. The optical signal passes through a first path of PSR 320 and is emitted from PSR 320 to free space on an associated transmitter or coupler. The optical signal is collimated by a first converging lens 302a, after which the optical signal encounters a Faraday rotator 355 of a single-stage isolator. The 0° TE optical signal passes through the first Faraday rotator 355, which rotates the polarization of the optical signal by 45°, producing a polarized optical signal that is primarily 45°. The resulting primarily 45° polarized optical signal leaves the Faraday rotator 355, is converged by a second converging lens 302b, and is then collected at a coupler or transmitter associated with IPC 330. The 45° polarized optical signal enters the polarization side port of the IPC 330, passes through the IPC 330, and exits as a TE optical signal from one of the component side ports of the IPC 330 to enter the second integrated optical chip 301b. As will become clear below, the IPC 330 requires a more sophisticated structure than the known integrated PSR described above in order to convert the 45° polarized optical signal to TE and perform the opposite conversion in the opposite direction.

[0068] Due to the operation of the Faraday rotator 355 and the arrangement of the PSR 320 and the IPC 330, any TE optical signal traveling in the other direction (ie, toward the first integrated optical chip 301a) within the second integrated optical chip 301b is substantially blocked.

[0069] The optical signal with TE polarization entering the IPC 330 via one of its component side ports is converted to a 45° polarized optical signal, emitted into free space, and collimated via the second converging lens 302b. The collimated optical signal encounters the Faraday rotator 355 from the rear side, which rotates the polarization of the 45° polarized optical signal by 45°, generating a mainly 90° polarized optical signal. The generated mainly 90° (TM) polarized optical signal encounters the PSR 320 set to have a polarization direction of 0° or TE on its first path, and is thus substantially redirected away from the first component side port, and is redirected to the second component side port via its second path to be discarded.

[0070] The IPC of isolator 300 and subsequent other embodiments are more sophisticated than the standard PSR and allow the 45° polarized light signal emitted by the Faraday rotator to be converted to a TE polarized light signal. IPCs are divided into two categories, Type I IPCs that can convert polarization states with equal amplitude components to TE, and Type II IPCs that can convert any polarization state to TE.

[0071] Reference Figure 4 , a system 4000 including a Type I IPC according to an embodiment will now be discussed.

[0072] System 4000 includes an IPC 4010 that includes a method for converting any polarization state having orthogonal components (e.g., E x and E y (TE and TM)) into a polarization state with substantially all incident power in a single component direction (e.g., E xor TE). For example, an optical signal that is linearly polarized at 45° (e.g., from the x-axis), whether "diagonal" or "anti-diagonal" polarization state, right-hand circular polarization (RHCP), left-hand circular polarization (LHCP), or any elliptical polarization state formed by a combination of TE and TM of equal amplitude and phase difference of an amount other than ±π / 2, 0, or π, can be converted to a linear polarization state, such as TE, that has approximately the same power as the original optical signal. In the context of the single-stage isolator 300 and other isolator embodiments, the IPC 4010 converts a 45° polarized optical signal from a Faraday rotator to TE, and performs the opposite operation on an optical signal traveling in the opposite direction. In embodiments such as the single-stage isolator 300, when combined with an associated PSR, this effectively blocks reverse transmission because, due to the polarization orientation of the PSR, it directs the TM optical signal from the Faraday rotator to a second component side port where the TM optical signal can be discarded. In embodiments such as (below Fig. 9 In an embodiment of the single-stage circulator 9000, reverse transmissions rerouted on the second port of the associated PSR are not discarded.

[0073] Regarding the structure, starting from the polarization side of the system 4000, the first port of the transmitter 4100 is used as the polarization side port of the IPC 4010. The transmitter 4100 can be any free space to chip converter that supports two polarization components (TE and TM) such as a grating or an inverted cone. The second port of the transmitter 4100 is coupled to a single polarization side port of a polarization beam splitter rotator (PSR) 4200, and the PSR 4200 is coupled to the first set of ports on the polarization side of the 2:1 beam splitter 4420 through the first set of waveguides 4001, 4003 via its component side ports. The first component side port of the PSR is coupled to the first waveguide 4001, and the second component side port of the PSR is coupled to the second waveguide 4003. A phase shifter 4320 is coupled along the first waveguide 4001. The first waveguide 4001 is coupled to a first port of a 2:1 beam splitter 4420, and the second waveguide 4003 is coupled to a second port of the 2:1 beam splitter 4420. The component side of the 2:1 beam splitter 4420 is coupled via a second set of ports (consisting of a single third port) to a component side port 4009 of an IPC 4010 represented here as a waveguide coupled to other optical components using polarization converted optical signals.

[0074] Regarding the function, at the transmitter 4100, the original optical signal of the original polarization state is input to the IPC 4010. After passing through the transmitter 4100, the optical signal enters the polarization beam splitter rotator (PSR) 4200, which splits the orthogonal polarization components of the optical signal, rotates one of them, and outputs it on a separate component side port. yThe component (TM) is rotated 90° to become TE polarization and is output from the first component side port of the PSR 4200 along the first waveguide 4001 as a first component optical signal “TM as TE”. x The component (TE) is output as a second component optical signal "TE" from the second component side port of the PSR 4200 along the second waveguide 4003. Since the effective refractive index affecting the TM and TE components is generally not equal, the TE and TM polarization components of the optical signal experience different phase shifts when passing through both the transmitter 4100 and the PSR 4200. This will be reflected in the phase of the first component optical signal and the second component optical signal emitted from the PSR 4200. For the operation of the polarization controller 4010, the absolute phase of the optical signal passing through the first set of waveguides 4001, 4003 is not important, only the relative phase difference Δθ between the optical signal passing through the first waveguide 4001 and the optical signal passing through the second waveguide 4003 is important. This relative phase difference Δθ depends not only on the phase shift caused by the transmitter 4100 and the PSR 4200, but also on the original phase difference between the orthogonal polarization components of the original optical signal. The first component optical signal "TM as TE" passes through a phase shifter 4320 coupled along the first waveguide 4001 that applies a phase shift of Δφ in the first component optical signal. The phase-shifted first component optical signal exits the phase shifter 4320, passes through the remaining portion of the first waveguide 4001, and enters the 2:1 beam splitter 4420 via its first port. The second component optical signal passes through the second waveguide 4003 and enters the 2:1 beam splitter 4420 via its second port. The 2:1 beam splitter 4420 effectively adds the optical signals received on its first set of ports to produce a final output optical signal output from its third port and through the component side port 4009. In order to optimize the output power of the final output optical signal, the optical signals input to the 2:1 beam splitter should be in phase, or have any phase difference that optimizes the power according to the internal structure of the 2:1 beam splitter 4420. To achieve this, the phase shift Δφ of the phase shifter 4320 is appropriately selected. In some embodiments, for example, when the 2:1 beam splitter is a Y-branch beam splitter, the phase shift Δφ is selected to be an integer multiple of 2π minus the relative phase difference Δθ to optimize the output power. It should be noted that in some embodiments, the phase shift Δφ of the phase shifter 4320 is selected to optimize other aspects of the final output optical signal, such as, for example, the signal strength of the modulated signal, the eye opening, and / or the bit error rate.

[0075] It should be noted that in some embodiments, rather than using separate transmitters 4100 and PSR 4200, a single transmitter is used that also functions as a polarization beam splitter rotator. In these embodiments, the two component side ports of the single transmitter are directly coupled to the first and second waveguides 4001 and 4003.

[0076] It should be noted that the relative phase of the first component optical signal “TM as TE” emitted from the transmitter 4100 and PSR 4200 on the first waveguide 4001 may lead or follow the phase of the second component optical signal “TE” emitted from the transmitter 4100 and PSR 4200 on the second waveguide 4003.

[0077] Since only the relative phase difference is relevant (and not the absolute phase), in some embodiments a phase shifter 4320 is positioned along the second waveguide 4003 and its phase shift Δφ is appropriately chosen.

[0078] Although the first component optical signal passing through the first waveguide 4001 is characterized as "TM as TE" and the second component optical signal passing through the second waveguide is also characterized as "TE", as long as the optical signals emitted from the transmitter 4100 and / or PSR 4200 are in the same (parallel) linear polarization state supported by both the first and second waveguides 4001 and 4003, they can be appropriately phase-shifted by the phase shifter 4320 and combined in the 2:1 beam splitter 4420. For example, in some cases, the transmitter 4100 and the PSR 4200 can split and rotate the polarization components so that the E of the incident optical signal is equal to or less than TE. x The component (TE) is rotated 90° to become TM polarized and output as “TE as TM”, and the E y The component (TM) is output as "TM", and both signals pass through waveguides 4001, 4003 that support "TM" mode transmission.

[0079] In some embodiments where the polarization of the original optical signal is known, the phase shifter 4320 is a fixed passive element.

[0080] In some embodiments, to handle various polarization states (orthogonal components with equal amplitudes), phase shifter 4320 is tunable and the polarization controller includes active control of phase shifter 4322 and optionally includes devices such as taps and photodiodes (similar to the following combined Figure 8 Various elements for power monitoring (such as those described above) are used to provide feedback to a controller for tuning the phase shift Δφ.

[0081] The phase shifter 4320 of this embodiment and the remaining embodiments can be implemented using a variety of different technologies, including but not limited to: thermo-optical, electro-optical, carrier injection, carrier depletion, liquid crystal or MEMS. Generally, thermo-optical technology is preferred due to its low optical loss.

[0082] In some embodiments (such as the following combination Fig. 9 4009), the IPC 4010 is simultaneously used in reverse (e.g., in a circulator) such that the first port of the transmitter 4100 serves as the output of the IPC 4010 for a signal incident on the component side port 4009. In this case, a linearly polarized optical signal, such as "TE", is transmitted into the component side port 4009, the signal is split and a relative phase difference Δφ is introduced by the phase shifter 4320, so that once rotated and recombined in the PSR 4200 and the transmitter 4100, the optical signal emitted from the transmitter 4100 has a desired polarization, such as (e.g., from the x-axis) 45° linear polarization, etc. Therefore, the phase shift Δφ is determined taking into account the desired polarization state of the output and the relative phase difference Δθ introduced by the transmitter 4100 and the PSR 4200.

[0083] Typically, the IPC 4010 uses a combination of a transmitter 4100 and / or a PSR 4200 to split two orthogonal polarization components (of equal amplitude) of an incident optical signal, rotate one to be parallel to the other, and use a phase shifter 4320 to control the relative phase of the two component optical signals before combining them in a 2:1 beamsplitter, and optionally (or simultaneously) is also capable of performing the reverse operation.

[0084] In some embodiments of a Type I polarization controller, the 2:1 beam splitter may be replaced by a 2:2 beam splitter that, for example, ignores one path, including, for example, a multi-mode interferometer (MMI) or a directional coupler.

[0085] This is what we will discuss now Figure 5 An example of a system 5000 including a Type I IPC according to an embodiment is shown in FIG.

[0086] The integrated photonic system 5000 includes an IPC 5010 that includes a device for converting any polarization state having orthogonal components (e.g., E x and E y (TE and TM)) into a polarization state with substantially all incident power in a single component direction (e.g., E xor TE). For example, an optical signal that is linearly polarized at 45° (e.g., from the x-axis), whether in a "diagonal" or "anti-diagonal" polarization state, right-hand circular polarization (RHCP), left-hand circular polarization (LHCP), or any elliptical polarization state formed by a combination of TE and TM of equal amplitude and a phase difference of an amount other than ±π / 2, 0, or π, can be converted to a linear polarization state, such as TE, that has approximately the same power as the original optical signal. In the context of the single-stage isolator 300 and other isolator embodiments, the IPC 5010 converts a 45° polarized optical signal from a Faraday rotator to TE, and performs the opposite operation on an optical signal traveling in the opposite direction. In embodiments such as the single-stage isolator 300, when combined with an associated PSR, this effectively blocks reverse transmission because, due to the polarization orientation of the PSR, it directs the TM optical signal from the Faraday rotator to a second component side port where the TM optical signal can be discarded. In embodiments such as (below Fig. 9 In an embodiment of the single-stage circulator 9000, reverse transmissions that are rerouted through the second port of the associated PSR are not discarded.

[0087] Starting from the polarization side of the system 5000, the first port of the transmitter 5100 is used as the polarization side port of the IPC 5010. The transmitter 5100 can be any free space to chip converter that supports two polarization components (TE and TM) such as a grating or an inverted cone. The second port of the transmitter 5100 is coupled to a single polarization side port of a polarization beam splitter rotator (PSR) 5200, and the PSR5200 is coupled to the first set of ports on the polarization side of the 2:2 beam splitter 5420 through the first set of waveguides 5001, 5003 via its component side ports. The first component side port of the PSR5200 is coupled to the first waveguide 5001, and the second component side port of the PSR5200 is coupled to the second waveguide 5003. A phase shifter 5320 is coupled along the first waveguide 5001. The first waveguide 5001 is coupled to a first port of a 2:2 beam splitter 5420, and the second waveguide 5003 is coupled to a second port of the 2:2 beam splitter 5420. The component side of the 2:2 beam splitter 5420 is coupled via a second set of ports (consisting of a third and a fourth port) to two component side ports 5009a, 5009b of the IPC 5010, represented here as waveguides (one or both of which are coupled to other optical components using polarization converted optical signals), respectively.

[0088] At the transmitter 5100, the original optical signal of the original polarization state is input to the IPC 5010. After passing through the transmitter 5100, the optical signal enters the polarization beam splitter rotator (PSR) 5200, which splits the orthogonal polarization components of the optical signal, rotates one of them, and outputs them on their respective component side ports. yThe component (TM) is rotated 90° into TE polarization and is output from the first component side port of the PSR 5200 along the first waveguide 5001 as a first component optical signal “TM as TE”. xThe component (TE) is output as a second component optical signal "TE" from the second component side port of the PSR 5200 along the second waveguide 5003. Since the effective refractive index affecting the TM and TE components is generally not equal, the TE and TM polarization components of the optical signal experience different phase shifts when passing through both the transmitter 5100 and the PSR 5200. This will be reflected in the phase of the first component optical signal and the second component optical signal emitted from the PSR 5200. For the operation of the polarization controller 5010, the absolute phase of the optical signal passing through the first set of waveguides 5001, 5003 is not important, only the relative phase difference Δθ between the optical signal passing through the first waveguide 5001 and the optical signal passing through the second waveguide 5003 is important. This relative phase difference Δθ depends not only on the phase shift caused by the transmitter 5100 and the PSR 5200, but also on the original phase difference between the orthogonal polarization components of the original optical signal. The first component optical signal "TM as TE" passes through a phase shifter 5320 coupled along the first waveguide 5001 that applies a phase shift of Δφ in the first component optical signal. The phase-shifted first component optical signal exits the phase shifter 5320, passes through the remaining portion of the first waveguide 5001, and enters the 2:2 beam splitter 5420 via the first port of the 2:2 beam splitter 5420. The second component optical signal passes through the second waveguide 5003, and enters the 2:2 beam splitter 5420 via the second port of the 2:2 beam splitter 5420. The 2:2 beam splitter 5420 effectively adds the optical signals received on its first set of ports to produce a final output optical signal that is output from one of the ports of its second set of ports (i.e., one of the third or fourth ports of the 2:2 beam splitter 5420) and through one of the component-side ports 5009a, 5009b. One of the third and fourth ports of the 2:2 beam splitter 5420 coupled to the other of the component side ports 5009a, 5009b generates an optical signal that is the difference between the two optical signals received on the first set of ports of the 2:2 beam splitter 5420. In order to optimize the output power of the final output optical signal, the optical signals input to the 2:2 beam splitter should be in phase, or have any phase difference that optimizes the power emitted through the intended component side ports 5009a, 5009b, depending on the internal structure of the 2:2 splitter 5420 (and which of the component side ports 5009a, 5009b is used as the "output"). For example, the 2:2 beam splitter 5420 can cause an even-mode incident optical signal to optimize the power on one of the two component side ports 5009a and 5009b while minimizing the power consumption on the other of the two component side ports 5009a and 5009b. In this case, the same 2:2 beam splitter may be such that an odd-mode incident optical signal optimizes the power on the other of the two component side ports 5009a and 5009b while minimizing the power on one of the two component side ports 5009a and 5009b.It should be noted that although in some embodiments only one of the two component side ports 5009a, 5009b is used as the desired output of the final output optical signal and the optical signal at the other of the two component side ports 5009a and 5009b is dropped or discarded, in some implementation schemes, the optical signals at both component side ports 5009a and 5009b are utilized and, in some cases, used for different purposes.

[0089] In order to achieve an appropriate relative phase difference for optimizing the output power, the phase shift Δφ of the phase shifter 5320 is appropriately selected. In some embodiments, the phase shift Δφ is selected to be an integer multiple of 2π minus the relative phase difference Δθ, while in other embodiments (odd mode optimized output), the phase shift Δφ is selected to be an integer multiple of π minus the relative phase difference Δθ plus 2π to optimize the output power. It should be noted that in some embodiments, the phase shift Δφ of the phase shifter 5320 is selected to optimize other aspects of the final output optical signal, such as, for example, the signal strength, eye opening, and / or bit error rate of the modulated signal.

[0090] In some embodiments, rather than using separate transmitters 5100 and PSRs 5200, a single transmitter or coupler is used that also functions as a polarization beam splitter rotator. In these embodiments, the two component side ports of the coupler are directly coupled to the first and second waveguides 5001 and 5003.

[0091] The relative phase of the first component optical signal "TM as TE" emitted from the transmitter 5100 and PSR 5200 through the first waveguide 5001 may lead or follow the phase of the second component optical signal "TE" emitted from the transmitter 5100 and PSR 5200 through the second waveguide 5003. In some embodiments, the phase shifter 5320 is positioned along the second waveguide 5003, and its phase shift Δφ is appropriately selected.

[0092] As long as the optical signals emitted from the transmitter 5100 and / or PSR 5200 are in the same (parallel) linear polarization state supported by both the first and second waveguides 5001 and 5003, they can be appropriately phase-shifted by the phase shifter 5320 and combined in the 2:2 beam splitter 5420. For example, in some cases, the transmitter 5100 and PSR 5200 can split and rotate the polarization components so that the E of the incident optical signal is x The component (TE) is rotated 90° to become TM polarization and output as "TE as TM", and the E in the incident optical signal y The component (TM) is output as "TM", and both signals travel through waveguides 5001 and 5003 which support "TM" mode transmission.

[0093] In some embodiments where the polarization of the original optical signal is known, the phase shifter 5320 is a fixed passive element.

[0094] In some embodiments, to handle various polarization states (orthogonal components with equal amplitudes), phase shifter 5320 is tunable and the polarization controller includes active control of phase shifter 5320 and optionally includes devices such as taps and photodiodes (similar to the following combined Figure 8 Various elements for power monitoring (such as those described above) are used to provide feedback to the controller for tuning the phase shift Δφ.

[0095] In some embodiments (such as the following combination Fig. 9 5009a, 5009b. In this case, a linearly polarized optical signal, such as "TE", is transmitted to one component side port (e.g., 5009a), the signal is split and a relative phase difference is introduced by the phase shifter 5320, so that once it is rotated and recombined in the PSR 5200 and the transmitter 5100, the optical signal emitted from the transmitter 5100 has a desired polarization, such as a linear polarization of 45° (e.g., from the x-axis). Therefore, the phase shift Δφ is determined by taking into account both the desired polarization state of the output and the relative phase difference Δθ introduced by the transmitter 5100 and the PSR 5200.

[0096] The polarization controller 5010 uses a combination of the transmitter 5100 and / or the PSR 5200 to split the two orthogonal polarization components (of the same amplitude) of the incident optical signal, rotates one to be parallel to the other, and uses a phase shifter 5320 to control the relative phase of the two component optical signals before they are combined in a 2:2 beam splitter, and can also perform reverse operations alternately or simultaneously.

[0097] Combination of the above Figure 4 and Figure 5 The discussed Type I polarization controllers 4010 and 5010, although described as receiving or generating optical signals of polarization states having orthogonal components of equal amplitude, can also be used with optical signals of other polarization states to change the degree of power loss in the generated optical signal. To process optical signals of any polarization state, a Type II IPC as described below can be used. In a PSR (e.g. Figure 3 PSR 320 or Fig. 9If the PSR 9020) is rotationally misaligned for any reason, and assuming that the Faraday rotator provides the required 45° polarization rotation of the optical signal passing through it, the rotated polarized optical signal entering the IPC will not be at 45°. In this case, the Type II IPC is able to rotate the non-45° polarized optical signal to the desired polarization, such as TE.

[0098] Reference Figure 6 , a system 6000 including a Type II IPC according to an embodiment will now be discussed.

[0099] As above Figure 4 and Figure 5 As noted in the description of the embodiments, the 2:1 beam splitter and the 2:2 beam splitter effectively add the first component optical signal and the second component optical signal they receive to produce an output optical signal, and generally the in-phase inputs of similar amplitude optimize the output power at the component side port of the polarization controller which serves as its output. If the phase or amplitude is not matched, the output power will not be optimized. This is why Type I polarization controllers are best suited for optical signals with equal amplitude polarization components. In order to allow operation at arbitrary polarization states where the polarization components have arbitrary phase differences and have arbitrary amplitude ratios, instead of using a single 2:1 or 2:2 beam splitter at the output of the polarization controller, a variable beam splitter is used.

[0100] System 6000 includes an IPC 6010 that includes a device for converting any polarization state having orthogonal components (e.g., E x and E y (TE and TM)) into a polarization state with substantially all incident power in a single component direction (e.g., E x or TE). For example, a linearly, circularly, or elliptically polarized optical signal can be converted to a specific linear polarization state, such as TE, that has substantially the same power as the original optical signal. In the case of the single-stage isolator 300 and other isolator embodiments, the IPC 6010 converts a 45° polarized optical signal from the Faraday rotator to TE, and performs a reverse operation on the optical signal passing in the reverse direction. In embodiments such as the single-stage isolator 300, when combined with an associated PSR, this effectively blocks reverse transmission because, due to the polarization orientation of the PSR, it directs the TM optical signal from the Faraday rotator to a second component side port where the TM optical signal can be discarded. In embodiments such as (below) Fig. 9 In an embodiment of the single-stage circulator 9000, reverse transmissions rerouted on the second port of the associated PSR are not discarded.

[0101] Starting from the polarization side of the system 6000, the first port of the transmitter 6100 is used as the polarization side port of the IPC 6010. The transmitter 6100 can be any free space to chip converter that supports two polarization components (TE and TM) such as a grating or an inverted cone. The second port of the transmitter 6100 is coupled to a single polarization side port of a polarization beam splitter rotator (PSR) 6200, which is coupled to the first set of ports on the polarization side of the 2:2 beam splitter 6420 via its component side ports on the first set of waveguides 6001 and 6003. The first component side port of the PSR 6200 is coupled to the first waveguide 6001, and the second component side port of the PSR 6200 is connected to the second waveguide 6003. A first phase shifter 6320 is connected along the first waveguide 6001. The first waveguide 6001 is coupled to the first port of the 2:2 beam splitter 6420, and the second waveguide 6003 is coupled to the second port of the 2:2 beam splitter 6440. The component side of the 2:2 beam splitter 6420 is coupled to the first group of ports on the polarization side of the 2:1 beam splitter 6440 on the second group of waveguides 6005, 6007 via the second group of ports (composed of the third and fourth ports). The 2:2 beam splitter 6420 is coupled to the third waveguide 6005 via its third port, and to the fourth waveguide 6007 via its fourth port. A second phase shifter 6340 is connected along the third waveguide 6005. The third waveguide 6005 is coupled to the first port of the 2:1 beam splitter 6440, and the fourth waveguide 6007 is coupled to the second port of the 2:1 beam splitter 6440. The component side of the 2:1 beam splitter 6440 is coupled via a second set of ports (consisting of a single third port) to a component side port 6009 of the IPC 6010 represented here as a waveguide coupled to other optical components using polarization converted optical signals.

[0102] At the transmitter 6100, the original optical signal of the original polarization state is input to the IPC 6010. After passing through the transmitter 6100, the optical signal enters the polarization beam splitter rotator (PSR) 6200, which splits the orthogonal polarization components of the optical signal, rotates one of them, and outputs them on their respective component side ports. y The component (TM) is rotated 90° into TE polarization and is output from the first component side port of the PSR 6200 along the first waveguide 6001 as a first component optical signal “TM as TE”. xThe component (TE) is output as a second component optical signal "TE" from the second component side port of the PSR 6200 along the second waveguide 6003. Since the effective refractive index affecting the TM and TE components is generally not equal, the TE and TM polarization components of the optical signal experience different phase shifts when passing through both the transmitter 6100 and the PSR 6200. This will be reflected in the phase of the first component optical signal and the second component optical signal emitted from the PSR 6200. For the operation of the polarization controller 6010, the absolute phase of the optical signal passing through the first set of waveguides 6001, 6003 is not important, only the relative phase difference Δθ between the optical signal passing through the first waveguide 6001 and the optical signal passing through the second waveguide 6003 is important. This relative phase difference Δθ depends not only on the phase shift caused by the transmitter 6100 and the PSR 6200, but also on the original phase difference between the orthogonal polarization components of the original optical signal. The first component optical signal "TM as TE" passes through a first phase shifter 6320 coupled along the first waveguide 6001 that applies a first phase shift of Δφ1 in the first component optical signal. The phase-shifted first component optical signal exits the first phase shifter 6320, passes through the remaining portion of the first waveguide 6001, and enters the 2:2 beam splitter 6420 via a first port of the 2:2 beam splitter 6420. The second component optical signal passes through a second waveguide 6003, and enters the 2:2 beam splitter 6440 via a second port of the 2:2 beam splitter 6420. The 2:2 splitter 6420 effectively adds the optical signals received on its first set of ports to generate an optical signal output from one of its second set of ports, and the optical signal generated by the other port of the second set of ports of the 2:2 beam splitter 6420 is the difference between the two optical signals received on the first set of ports of the 2:2 beam splitter 6420. To ensure that the optical signals arriving at the 2:1 beam splitter 6440 have equal power, the optical signals input to the 2:2 beam splitter 6420, regardless of their relative power, should have a phase difference of ±90° (±π / 2), or any phase difference that equalizes the power of the signals emitted on the second set of waveguides 6005 and 6007, depending on the internal structure of the 2:2 beam splitter 6420. This ensures that the two optical signals emitted from the 2:2 beam splitter 6420 (i.e., one is the sum of the optical signals input to the 2:2 beam splitter 6420, and the other is the difference of the optical signals output from the 2:2 beam splitter 6420) have the same power.

[0103] In order to obtain the appropriate relative phase difference for balancing the output power from the 2:2 beam splitter 6420, the first phase shift Δφ1 of the first phase shifter 6320 is appropriately selected, that is, a relative phase difference of ±90° (±π / 2) is selected. In some embodiments, the first phase shift Δφ1 is selected to be an integer multiple of 2π minus an additional relative phase difference Δθ offset by ±90° (±π / 2).

[0104] The third and fourth component optical signals of equal power are emitted from the 2:2 beam splitter 6420 on the third and fourth waveguides 6005 and 6007, respectively. Depending on the relative amplitudes of the optical signals input to the 2:2 beam splitter 6420, the third and fourth component optical signals emitted from the 2:2 beam splitter 6420 to the third and fourth waveguides 6005 and 6007 will have a relative phase difference Δθ2. The third component optical signal passing through the third waveguide 6005 passes through a second phase shifter 6340 coupled along the third waveguide 6005 that applies a second phase shift of Δ2 in the third component optical signal. The phase-shifted third component optical signal is emitted from the phase shifter 6340, passes through the remaining portion of the third waveguide 6005, and enters the 2:1 beam splitter 6440 via the first port of the 2:1 beam splitter 6440. The fourth component optical signal passes through the fourth waveguide 6007 and enters the 2:1 beam splitter 6440 via the second port of the 2:1 beam splitter 6440. The 2:1 beam splitter 6440 effectively adds the optical signals received on its first set of ports to generate a final output optical signal output from the third port of the 2:1 beam splitter 6440 and through the component side port 6009. In order to optimize the output power of the final output optical signal, the optical signals input to the 2:1 beam splitter 6440 should be in phase, or have any phase difference that optimizes the power according to the internal structure of the 2:1 beam splitter 6440. To achieve this, the second phase shift Δφ2 of the second phase shifter 6340 is appropriately selected, and in some embodiments, the second phase shift Δφ2 is selected to be an integer multiple of 2π minus the second relative phase difference Δθ2 to optimize the output power. It should be noted that in some embodiments, the second phase shift Δφ2 of the second phase shifter 6340 is selected to optimize other aspects of the final output optical signal, such as, for example, signal strength, eye opening and / or bit error rate of the modulated signal.

[0105] In some embodiments, rather than using separate transmitters 6100 and PSR 6200, a single transmitter is used that also functions as a polarization beam splitter rotator. In these embodiments, the two component side ports of the single transmitter are directly coupled to the first and second waveguides 6001 and 6003. The relative phase of the first component optical signal "TM as TE" emitted from the transmitter 6100 and PSR 6200 on the first waveguide 6001 may lead or follow the phase of the second component optical signal "TE" emitted from the transmitter 6100 and PSR 6200 on the second waveguide 6003. In some embodiments, one or both of the first phase shifter 6320 and the second phase shifter 6340 are positioned along the second waveguide 6003 and the fourth waveguide 6007, respectively, and their phase shifts Δφ1 and Δφ2 are appropriately selected.

[0106] As long as the optical signals emitted from the transmitter 6100 and / or PSR 6200 are in the same (parallel) linear polarization state supported by the first waveguide 6001 and the second waveguide 6003, they can be appropriately phase-shifted by the first phase shifter 6320 and manipulated by the remaining elements of the polarization controller 6010. For example, in some cases, the transmitter 6100 and PSR 6200 can split and rotate the polarization components so that the E of the incident optical signal is x The component (TE) is rotated 90° to TM polarization and output as “TE as TM”, and the E of the incident optical signal y The component (TM) output is "TM", and both signals pass through waveguides 6001, 6003 that support "TM" mode transmission.

[0107] In some embodiments where the polarization of the original optical signal is known, phase shifters 6320 and 6340 are fixed passive elements.

[0108] In some embodiments, to handle arbitrary polarization states, phase shifters 6320 and 6340 are adjustable, and the polarization controller includes active control of phase shifters 6320 and 6340, and optionally includes devices such as taps and photodiodes (similar to the following combined Figure 8 Those that will be described) are used for various elements of power monitoring to provide feedback to the controller for tuning the phase shifts Δφ1, Δφ2.

[0109] In some embodiments (such as the following combination Fig. 9 ), the IPC 6010 is simultaneously used in reverse (e.g., in a circulator) such that the first port of the transmitter 6100 is used as the output of the IPC 6010 for the optical signal incident on the component side port 6009. In this case, a linearly polarized optical signal, such as "TE", is transmitted into the component side port 6009, the signal is split and a relative phase difference Δφ2 is introduced by the second phase shifter 6340, so that once it is split by the 2:2 beam splitter 6420 and another relative phase difference Δφ1 is introduced by the first phase shifter 6320, and once it is rotated and recombined in the PSR 6200 and the transmitter 6100, the optical signal emitted from the transmitter 6100 has the desired polarization, such as (e.g., from the x-axis) 45° linear polarization. Therefore, the phase shifts Δφ1, Δφ2 are determined taking into account both the desired polarization state of the output and the relative phase difference Δθ introduced by the transmitter 6100 and the PSR 6200.

[0110] Typically, the polarization controller 6010 uses a combination of the transmitter 6100 and / or the PSR 6200 to split two orthogonal polarization components of an arbitrarily polarized incident optical signal, and rotates one to be parallel to the other, and uses a first phase shifter 6320 to control the relative phases of the two component optical signals so that they have a relative phase difference of ±90° (±π / 2) before passing through the 2:2 beam splitter 6420, and optical signals with equal power are generated from the 2:2 beam splitter 6420, and before they are combined in the 2:1 beam splitter 6440 for output, one of them is further phase shifted by Δφ2 using a second phase shifter 6340 to make them in phase, and the opposite operation can also be performed (alternatively or simultaneously).

[0111] In some embodiments of a Type II polarization controller, the 2:1 beam splitter may be replaced with a component-side 2:2 beam splitter including, for example, a multi-mode interferometer (MMI) or a directional coupler (eg, one output is omitted).

[0112] This is the basis for the discussion now. Figure 7 The illustrated embodiment has an example of an integrated photonic system 7000 including a Type II integrated polarization controller.

[0113] System 7000 includes an IPC 7010 that includes on-chip components for converting any polarization state having orthogonal components (e.g., E x and E y (TE and TM)) into a polarization state with substantially all incident power in a single component direction (e.g., E x or TE). For example, a linear, circular, or elliptically polarized optical signal can be converted to a specific linear polarization state, such as TE, of approximately the same power as the original optical signal. In the case of the single-stage isolator 300 and other isolator embodiments, the IPC 7010 converts a 45° polarized optical signal from the Faraday rotator to TE, and performs the opposite operation on the optical signal passing in the reverse direction. In embodiments such as the single-stage isolator 300, when combined with an associated PSR, this effectively blocks reverse transmission because, due to the polarization orientation of the PSR, it directs the TM optical signal from the Faraday rotator to a second component side port where the TM optical signal can be discarded. In embodiments such as (below) Fig. 9 In an embodiment of the single-stage circulator 9000, reverse transmissions rerouted through the second port of the associated PSR are not discarded.

[0114] Starting from the polarization side of the system 7000, the first port of the transmitter 7100 is used as the polarization side port of the IPC 7010. The transmitter 7100 can be any free space to chip converter that supports two polarization components (TE and TM) such as a grating or an inverted cone. The second port of the transmitter 7100 is coupled to a single polarization side port of a polarization beam splitter rotator (PSR) 7200, which is coupled to the first set of ports on the polarization side of the polarization side 2:2 beam splitter 7420 via its component side ports on the first set of waveguides 7001 and 7003. The first component side port of the PSR 7200 is coupled to the first waveguide 7001, and the second component side port of the PSR 7200 is coupled to the second waveguide 7003. A first phase shifter 7320 is coupled along the first waveguide 7001. The first waveguide 7001 is coupled to the first port of the polarization-side 2:2 beam splitter 7420, and the second waveguide 7003 is coupled to the second port of the polarization-side 2:2 beam splitter 7420. The component side of the polarization-side 2:2 beam splitter 7420 is coupled to the first group of ports on the polarization side of the element-side 2:2 splitter 7440 on the second group of waveguides 7005, 7007 via the second group of ports (composed of the third and fourth ports). The polarization-side 2:2 beam splitter 7420 is coupled to the third waveguide 7005 via its third port, and to the fourth waveguide 7007 via its fourth port. A second phase shifter 7340 is connected along the third waveguide 7005. The third waveguide 7005 is coupled to the first port of the component-side 2:2 beam splitter 7440, and the fourth waveguide 7007 is coupled to the second port of the component-side 2:2 beam splitter 7440. The component side of the element-side 2:2 splitter 7440 is coupled via a second set of ports (consisting of the third and fourth ports) to two component-side ports 7009a, 7009b of the IPC 7010, represented here as waveguides (one or both of which are coupled to other optical elements using polarization-converted optical signals).

[0115] At the transmitter 7100, the original optical signal of the original polarization state is input to the IPC 7010. After passing through the transmitter 7100, the optical signal enters the polarization beam splitter rotator (PSR) 7200, which splits the orthogonal polarization components of the optical signal, rotates one of them, and outputs them on their respective component side ports. yThe component (TM) is rotated 90° into TE polarization and is output from the first component side port of PSR 7200 along the first waveguide 7001 as a first component optical signal "TM as TE". The Ex component (TE) of the incident optical signal is output from the second component side port of PSR 7200 along the second waveguide 7003 as a second component optical signal "TE". Since the effective refractive index affecting the TM and TE components is generally not equal, the TE and TM polarization components of the optical signal experience different phase shifts when passing through both the transmitter 7100 and the PSR 7200. This will be reflected in the phase of the first component optical signal and the second component optical signal emitted from the PSR 7200. For the operation of the polarization controller 7010, the absolute phase of the optical signal passing through the first set of waveguides 7001, 7003 is not important, only the relative phase difference Δθ between the optical signal passing through the first waveguide 7001 and the optical signal passing through the second waveguide 7003 is important. This relative phase difference Δθ depends not only on the phase shift caused by the transmitter 7100 and the PSR 7200, but also on the original phase difference between the orthogonal polarization components of the original optical signal. The first component optical signal "TM as TE" passes through the first phase shifter 7320 coupled along the first waveguide 7001 to apply a first phase shift of Δφ1 in the first component optical signal. The phase-shifted first component optical signal emerges from the first phase shifter 7320, passes through the remaining portion of the first waveguide 7001, and enters the polarization side 2:2 beam splitter 7420 via the first port of the 2:2 beam splitter 7420. The second component optical signal passes through the second waveguide 7003 and enters the polarization side 2:2 beam splitter 7420 via the second port of the 2:2 beam splitter 7420. The 2:2 beam splitter 7420 effectively adds the optical signals received on its first group of ports to produce an optical signal output from one of the second group of ports of the 2:2 beam splitter 7420, and the other of the second group of ports of the 2:2 beam splitter 7420 produces an optical signal that is the difference between the two optical signals received on the first group of ports of the polarization side 2:2 beam splitter 7420. In order to ensure that the power of the optical signals arriving at the component side 2:2 beam splitter 7440 is equal, the optical signals input to the polarization side 2:2 beam splitter 7420 should have a phase difference of ±90° (±π / 2) regardless of their relative power, or any phase difference that equalizes the power of the signals emitted on the second group of waveguides 7005 and 7007 depending on the internal structure of the 2:2 beam splitter 7420. This ensures that the two optical signals emitted from the polarization side 2:2 beam splitter 7420 (i.e., one is the sum of the optical signals input to the polarization side 2:2 beam splitter 7320, and the other is the difference of the optical signals output to the polarization side 2:2 beam splitter 7420) have the same power.

[0116] In order to achieve an appropriate relative phase difference for balancing the output power from the polarization-side 2:2 beam splitter 7420, the first phase shift Δφ1 of the first phase shifter 7320 is appropriately selected, that is, a relative phase difference of ±90° (±π / 2) is selected. In some embodiments, the first phase shift Δφ1 is selected to be an integer multiple of 2π minus an additional relative phase difference Δθ offset by ±90° (±π / 2).

[0117] The third and fourth component optical signals of equal power are emitted from the polarization side 2:2 beam splitter 7420 on the third waveguide 7005 and the fourth waveguide 7007, respectively. The third and fourth component optical signals emitted from the polarization side 2:2 beam splitter 7420 to the third waveguide 7005 and the fourth waveguide 7007 will have a relative phase difference Δθ2 depending on the relative amplitude of the optical signals input to the polarization side 2:2 beam splitter 7320. The third component optical signal passing through the third waveguide 7005 passes through the second phase shifter 7340 coupled along the third waveguide 70005, which applies Δφ2 to the third component optical signal. The phase-shifted third component optical signal is emitted from the phase shifter 7340, passes through the remaining portion of the third waveguide 7005, and enters the component side 2:2 beam splitter 7440 via the first port of the 2:2 beam splitter 7440. The fourth component optical signal passes through the fourth waveguide 7007 and enters the element side 2:2 beam splitter 7440 via the second port of the 2:2 beam splitter 7440. The component side 2:2 beam splitter 7440 effectively adds the optical signals received on its first set of ports to produce a final output optical signal output from one of the ports of its second set of ports (i.e., one of the third or fourth ports of the component side 2:2 beam splitter 7440) and through one of the component side ports 4009a and 4009b. The other of the third or fourth ports of the component side 2:2 beam splitter 7440 connected to the other of the component side ports 7009a and 7009b produces an optical signal that is the difference between the two optical signals received on the first set of ports of the component side 2:2 beam splitter 7440.

[0118] In order to optimize the output power of the final output optical signal, the optical signal input to the component-side 2:2 beam splitter 7440 should be in phase, or have any phase difference that optimizes the power according to the internal structure of the component-side 2:2 beam splitter 7410. To achieve this, the second phase shift Δφ2 of the second phase shifter 7340 is appropriately selected, and in some embodiments, the second phase shift Δφ2 is selected to be an integer multiple of 2π minus the second relative phase difference Δθ2 to optimize the output power. It should be noted that in some embodiments, the second phase shift Δφ2 of the phase shifter 7340 is selected to optimize other aspects of the final output optical signal, such as, for example, the signal strength, eye opening and / or bit error rate of the modulation signal.

[0119] In some embodiments, instead of using separate transmitters 7100 and PSR 7200, a single transmitter is used that also functions as a polarization beam splitter rotator. In these embodiments, the two component side ports of the single transmitter are directly coupled to the first waveguide 7001 and the second waveguide 7003. The relative phase of the first component optical signal "TM as TE" emitted from the transmitter 7100 and PSR 7200 on the first waveguide 7001 may lead or follow the phase of the second component optical signal "TE" emitted from the transmitter 7100 and PSR 7200 on the second waveguide 7003. In some embodiments, one or both of the first phase shifter 7320 and the second phase shifter 7340 are positioned along the second waveguide 7003 and the fourth waveguide 7007, respectively, and their phase shifts Δφ1 and Δφ2 are appropriately selected.

[0120] As long as the optical signals emitted from the transmitter 7100 and / or PSR 7200 are in the same (parallel) linear polarization state supported by the first waveguide 7001 and the second waveguide 7003, they can be appropriately phase-shifted by the first phase shifter 7320 and operated by the remaining elements of the polarization controller 7010. For example, in some cases, the transmitter 7100 and PSR 7200 can split and rotate the polarization components so that the E of the incident optical signal is x The component (TE) is rotated 90° to TM polarization and output as “TE as TM”, and the E of the incident optical signal y The component (TM) output is "TM", and both signals pass through waveguides 7001, 7003 that support "TM" mode transmission.

[0121] In some embodiments where the polarization of the original optical signal is known, phase shifters 7320 and 7340 are fixed passive elements.

[0122] In some embodiments, phase shifters 7320 and 7340 are adjustable to handle arbitrary polarization states, and the polarization controller includes active control of phase shifters 7320 and 7340, and optionally includes devices such as taps and photodiodes (similar to the following combined Figure 8 Those that will be described) are used for various elements of power monitoring to provide feedback to the controller for tuning the phase shifts Δφ1, Δφ2.

[0123] In some embodiments (such as the following combination Fig. 9), the IPC 7010 is simultaneously used in reverse (e.g., in a circulator) such that the first port of the transmitter 7100 is used as the output of the IPC 7010 for optical signals incident on one or more component side ports 7009a, 7009b. In this case, a linearly polarized optical signal, such as "TE", is transmitted to one component side port (e.g., 7009a), the signal is split and a relative phase difference Δφ2 is introduced by the second phase shifter 7340, so that once split by the polarization side 2:2 beam splitter 7420 and another relative phase difference Δφ1 is introduced by the first phase shifter 7320, once rotated and recombined in the PSR 7200 and the transmitter 7100, the optical signal emitted from the transmitter 7100 has the desired polarization, such as a linear polarization of 45° (e.g., from the x-axis). Therefore, the phase shifts Δφ1, Δφ2 are determined by taking into account both the desired polarization state of the output and the relative phase difference Δθ introduced by the transmitter 7100 and the PSR 7200.

[0124] Typically, the polarization controller 7010 uses a combination of the transmitter 7100 and / or the PSR 7200 to split two orthogonal polarization components of an arbitrarily polarized incident optical signal, and rotates one to be parallel to the other, and uses a first phase shifter 7320 to control the relative phase of the two component optical signals so that they have a relative phase difference of ±90° (±π / 2) before passing through the polarization-side 2:2 beam splitter 7420, and optical signals with equal power are generated from the 2:2 beam splitter 7420, and before they are combined in the component-side 2:2 beam splitter 7440 for output, one of them is further phase-shifted by Δφ2 using a second phase shifter 7340 so that they are in phase or have a relative phase with optimized power, and the opposite operation can also be performed.

[0125] Reference Figure 8 , a method including a method capable of controlling based on feedback according to an embodiment will now be described. Figure 6 System 8000 of Type II IPC 8010 shown.

[0126] Such as Figure 6 and Figure 7 The shown Type II IPC is well suited to processing optical signals of any arbitrary polarization state. However, in the case of receiving optical signals whose polarization state is imprecise or may be offset, the phase shift provided by the first and second phase shifters should be adjusted in response to the polarization of the original optical signal. To achieve this, some form of detection and feedback control should be implemented.

[0127] Starting from the polarization side of the system 8000, the first port of the transmitter 8100 is used as the polarization side port of the IPC 8010 and receives the original optical signal from, for example, free space. The transmitter 8100 can be any free space to chip converter that supports two polarization components (TE and TM), such as a grating or an inverted cone. The second port of the transmitter 8100 is coupled to a single polarization side port of a polarization beam splitter rotator (PSR) 8200, which is coupled to the first set of ports on the polarization side of the 2:2 beam splitter 8420 via its component side ports through the first set of waveguides 8001 and 8003. The first component side port of the PSR 8200 is coupled to the first waveguide 8001, and the second component side port of the PSR 8202 is coupled to the second waveguide 8003. A first tunable phase shifter 8320 is coupled along the first waveguide 8001. The first waveguide 8001 is coupled to a first port of a 2:2 beam splitter 8420, and the second waveguide 8003 is coupled to a second port of a 2:2 beam splitter 8450. The component side of the 2:2 beam splitter 8420 is coupled to a first group of ports on the polarization side of a 2:1 beam splitter 8440 via a second group of ports (consisting of a third and a fourth port) through a second group of waveguides 8005, 8007. The 2:2 beam splitter 8420 is coupled to a third waveguide 8005 via its third port, and to a fourth waveguide 8007 via its fourth port. A second tunable phase shifter 8340 is coupled along the third waveguide 8005. The third waveguide 8005 is coupled to a first port of a 2:1 beam splitter 8440, and the fourth waveguide 8007 is coupled to a second port of the 2:1 beam splitter 8440. The component side port of the 2:1 beam splitter 8440 is coupled to a component side port 8009 of the IPC 8010 which serves as its output, here represented as a waveguide coupled to other optical components using polarization converted optical signals. An optical tap 8009c is coupled to the component side port 8009 of the IPC 8010. A light detecting element such as a photodiode 8510 is coupled to the tap 8009c. The photodiode 8510 is electrically coupled to the controller 8500, which itself is electrically coupled to the first tunable phase shifter 8320 and the second tunable phase shifter 8340.

[0128] Figure 8 The IPC 8010 is roughly similar to Figure 6The embodiment shown in FIG. 8 works in the manner of the embodiment shown, but additional elements provide detection, feedback and control to optimize power. An optical tap 8009c coupled to the component side port 8009 of the IPC 8010 is used to tap a small amount of the output optical signal (e.g., 1%). A photodiode 8510 is used to measure the intensity of the output optical signal passing through the output of the component side port 8009 using the light received on the tap 8009c, thereby measuring its power. The controller 8500 receives an electrical signal from the photodiode 8510 indicating the amount of light measured. In response to the measurement, the controller 8500 determines what the first phase shift and the second phase shift applied by the first phase shifter 8320 and the second phase shifter 8340 should be, or the amount by which one or both of the first phase shift and the second phase shift should be adjusted. The controller 8500 then sends an electrical control signal to the first phase shifter 8320 and the second phase shifter 8340 to appropriately adjust one or both of them. When the polarization state of the original optical signal is inaccurate, the control loop can be systematically used to search and find the optimal settings of the first phase shifter 8320 and the second phase shifter 8340, and can also be used to fine-tune or continuously adjust the first phase shifter 8320 and the second phase shifter 8340 when the polarization state of the original optical signal drifts, offsets, or otherwise changes slowly.

[0129] In a similar way, you can Figure 7 The illustrated embodiment operates in a substantially similar manner to an IPC providing detection, feedback and control to optimize power. Figure 7 A variation of IPC with Figure 8 In a similar manner as shown, a tap and a photodiode can be used at one or both of the component side ports 7009a, 7009b. In some cases, the optical signal emitted from one of the component side ports is not for further use, but for inferring the properties of the optical signal emitted from the other component side port. For example, in this embodiment, the power of the optical signal emitted on one of the component side ports 7009a, 7009b represents the power of the optical signal emitted at the other port in the component side ports 7009a, 7000b. Using two detection elements to monitor power and / or phase can provide more information for the improvement of the control of the first phase shifter 7320 and the second phase shifter 7340.

[0130] It should also be noted that the first, second, third and fourth waveguides (e.g. Figure 8 Additional taps and photodiodes are provided for additional power monitoring to enable more efficient and / or more accurate adjustment of the control loop. For example, the monitoring of the equal power emitted on the second set of waveguides 8005, 8007 can be used directly to adjust the first phase shifter 8320.

[0131] In the case of the isolator and circulator embodiments herein, although the PSR, Faraday rotator, and reflector that interact with the optical signal before it encounters the IPC theoretically produce an original optical signal with a known polarization, there are various manufacturing defects and differences that can cause such polarization to deviate from a desired or expected state. In addition, physical changes within the device over time or in response to environmental changes (e.g., ambient temperature) can cause the polarization of the optical signal as it enters the IPC to shift. In a reciprocal manner, when used in the opposite direction, the polarization state of the optical signal exiting the IPC toward the Faraday rotator may need to be shifted to achieve the desired function. In embodiments such as the single-stage isolator 300, one or both of the first phase shifter 8320 and the second phase shifter 8340 can be adjusted to optimize the blocking of reverse transmission, optimize the power of forward transmission, or optimize the ratio of forward transmission power to reverse transmission power. In embodiments such as (below Fig. 9 In an embodiment of the single-stage circulator 9000, one or both of the first phase shifter 8320 and the second phase shifter 8340 may be adjusted to optimize forward and reverse transmission power.

[0132] It should be understood that Figure 8 The feedback, control and drive circuits shown may include processors, memory, interfaces and / or other components that may be implemented external to or on the same integrated platform as the IPC, including, for example, integrated within the same substrate or wafer, integrated or co-located on a common substrate or platform, or electrically and / or optically linked within the same device or across multiple devices across multiple platforms including the IPC.

[0133] Now refer to Fig. 9 , based the discussion on something like Figure 3 The integrated photon circulator 9000 of the single stage isolator design is shown. The integrated photon circulator 9000 also completely omits the dual stage isolator and all polarizers and includes only a single stage Faraday rotator, but in order to make the device function as a circulator, the two component side ports of the PSR are used, rather than as in Figure 3 In the embodiment of the present invention, one of them is discarded.

[0134] Regarding the structure, the first integrated optical chip 9001a (other waveguides and internal devices are not shown) includes a polarization beam splitter rotator PSR 9020.

[0135] The PSR 9020 is coupled to the rest of the first integrated optical chip 9001a on two optical paths via its two component side ports 9100a and 9100b, and is coupled into free space on its polarization side port via a transmitter or coupler (not shown). The PSR 9020 is oriented so that the polarization of its first path is along the x-axis (E xor TE) direction or 0°. The first converging lens 9002a is located between the first integrated optical chip 9001a and the single-stage isolator including a Faraday rotator 9055 for applying a 45° rotation. The second converging lens 9002b is arranged between the Faraday rotator 9055 and the second integrated optical chip 9001b, and the second integrated optical chip 9001b includes a device such as a device similar to the above combination. Figure 4 , Figure 5 , Figure 6 , Figure 7 or Figure 8 The illustrated integrated polarization controller is an integrated polarization controller (IPC) 9030. The IPC 9030 is coupled to a transmitter or coupler (not shown) via its polarization side port and is coupled to the rest of the second integrated optical chip 9001b via one of its component side ports (such as port 9009a).

[0136] exist Fig. 9 In the figure, an IPC 9030 with two component side ports is shown, and in the three-port circulator variant, its second component side output port 9009b is not used to circulate the optical signal, but can be used for monitoring or can be decoupled and / or terminated in other ways. In the four-port circulator variant, the second component side output port 9009b can be used for input and output of optical signals.

[0137] It should be understood that IPC 9030 can be similar to incorporating Figure 4 , Figure 6 or Figure 8 The IPC described has only one component side port corresponding to 9009a, in which case the integrated circulator 9000 will still operate in much the same manner as the three-port circulator described below.

[0138] Regarding functionality, PSR 9020 receives an optical signal (TE) on a waveguide within the first integrated photonic chip 9001a at its first component side port. The optical signal passes through the first path of PSR 9020 and is emitted from PSR 9020 as a TE optical signal through an associated transmitter or coupler to free space. The optical signal (E x) is collimated by the first converging lens 9002a, after which it encounters the Faraday rotator 9055 of the single-stage isolator. The 0° optical signal passes through the first Faraday rotator 9055, which rotates the polarization of the optical signal by 45°, to generate a polarized optical signal mainly at 45°. The generated polarized optical signal mainly at 45° leaves the Faraday rotator 9055, is converged by the second converging lens 9002b, and is then collected at a coupler or transmitter associated with the IPC 9030. The 45° polarized optical signal enters the polarization side port of the IPC 9030, passes through the IPC 9030, and is emitted from the first component side port 9009a of the IPC 9030 as a TE optical signal to enter the second integrated optical chip 9001b.

[0139] Due to the operation of the Faraday rotator 9055 and the arrangement of the PSR 9020, optical signals (typically having TE polarization) traveling in the other direction (ie, toward the first integrated optical chip 9001a) within the second integrated optical chip 9001b are rerouted.

[0140] The optical signal with TE polarization entering the IPC 9030 via the component side port 9009a of the IPC 9030 is converted into a 45° polarized optical signal, emitted into free space, and collimated via the second converging lens 9002b. The collimated optical signal encounters the Faraday rotator 9055 from the rear side, which rotates the polarization of the optical signal by 45°, generating a polarized optical signal mainly at 90°. The generated mainly 90° (E y The polarized optical signal for TE (or TM) encounters the PSR 9020 arranged as a first path with an orientation of 0° (or for TE), so the TM optical signal received through its polarization side port is rerouted through the second component side port 9100b after being rotated 90° to be emitted as a TE optical signal.

[0141] In the three-port circulator variant, the TE polarized optical signal entering the IPC 9020 via its second component side port 9100b is converted to TM (90° or E y ) polarized optical signal, is emitted into free space, and is collimated via the first converging lens 9002a. The collimated optical signal encounters the Faraday rotator 9055 from the front side, which rotates the polarization of the optical signal by 45°, and generates a polarized optical signal mainly at 135°. Since the IPC is arranged so that the polarized optical signal at 45° is emitted as TE through its first component side port 9009a, the polarized optical signal mainly at 135° that encounters the IPC 9030 is rerouted through its second component side port 9001b, and the optical signal is discarded at the second component side port 9001b.

[0142] In the four-port circulator variation, a TE optical signal entering any one of the four ports is forwarded to another port instead of being discarded.

[0143] In the four-port circulator variant, the optical signal with TE polarization entering the PSR 9020 via the second component side port 9100b of the PSR 9020 is converted to TM (90° or E y ) polarized optical signal, is emitted into free space, and is collimated via the first converging lens 9002a. The collimated optical signal encounters the Faraday rotator 9055 from the front side, which rotates the polarization of the optical signal by 45°, and generates a polarized optical signal mainly at 135°. Since the IPC is arranged so that the polarized optical signal at 45° is emitted as TE on its first component side port 9009a, the polarized optical signal mainly at 135° that encounters the IPC 9030 is rerouted to be emitted as TE through its second component side port 9001b.

[0144] In the four-port circulator variant, the optical signal with TE polarization entering the IPC 9030 via the second component side port 9009b of the IPC 9030 is converted into a polarized optical signal of 135°, launched into free space, and collimated via the second converging lens 9002b. The collimated optical signal encounters the Faraday rotator 9055 from the rear side, which rotates the polarization of the optical signal by 45°, generating a polarized optical signal mainly of 180° (i.e., 0°). The generated mainly 0° (E x The polarized optical signal (TE or TE) encounters the PSR 9020 arranged to have a first path with an orientation of 0°, so the TE optical signal received through its polarization side port is forwarded through its first component side port 9100a to be emitted as a TE optical signal.

[0145] Based on the above it should be understood that, generally speaking, Fig. 9 The Integrated Circulator 9000 can be used as a three-port or four-port circulator.

[0146] In some embodiments, a similar method to Figure 3 and Fig. 9 An integrated isolator or circulator as shown in FIG. Fig.10 Such an integrated isolator or circulator device 1000 is shown in FIG. Fig.10 The structure and function of the device 1000 are similar to Figure 3 and Fig. 9 Embodiment of the invention.

[0147] It should be noted that the device 1000 and the IPC are different depending on whether only one component side port of the PSR (and IPC) is used or both component side ports are used. Figures 10 to 16The devices of the remaining embodiments shown can be implemented as three-port or four-port circulators or isolators. In embodiments using two component-side ports of a PSR, the device can be implemented as a circulator, and in embodiments using only one component-side port of a PSR, the device can be implemented as an isolator.

[0148] It should be noted that in Figures 10 to 16 In the example, only an IPC with two component side ports is shown, and it should be understood that two types of IPCs, such as Figure 4 and Figure 6 An IPC with a single component side port such as an IPC in Figure 5 and Figure 7 All IPCs with two component side ports are contemplated. It should also be noted that all IPCs and all PSRs are aligned so that their polarization side ports face the Faraday rotator.

[0149] As in the above-described embodiments, the device 1000 includes a first integrated optical chip 1010a, which includes a PSR 1020. To compensate for the lack of a second lens, a single silicon aspheric converging lens 1002 can be used between the first integrated optical chip 1010a and the Faraday rotator (45°) 1055 to converge the optical signal therebetween to the polarization side port of the PSR 1020 and the transmitter or coupler of the IPC 1030. Materials other than silicon, such as glass or fused quartz, can be used for the aspheric converging lens 1002. It should be noted that although the converging lenses of this embodiment and other disclosed embodiments are described as aspheric, the use of a lens with a simple spherical surface may produce some additional wavefront errors and thus cause coupling losses with the associated PSR or IPC. Generally, a converging lens 1002 with a high refractive index is preferred. The optical signal from the Faraday rotator is transmitted to the IPC 1030 (Type I or Type II) of the second integrated optical chip 1010b. Lens tolerances can be compensated by alignment, and in some embodiments, the converging lens 1002 is provided with active alignment to maximize coupling with the IPC 1030. Using a single lens can reduce the footprint, with the device footprint totaling only 2.1 mm x 0.3 mm in one embodiment.

[0150] In some embodiments, a device using multiple beams may be implemented, such as Fig.11 In some embodiments, the lens array is controlled by a single active alignment of a single substrate. In some embodiments, Fig.11The multi-beam embodiment enables a device footprint of only 2.5 mm x 2.5 mm for 8 channels (only 3 channels are shown).

[0151] As in the above-described embodiments, the device 1100 includes a first integrated optical chip 1110a, but includes a set of PSRs 1120 for multiple beams. To compensate for the lack of a second lens, a single silicon substrate 1102 including an aspheric converging lens array is used between the first integrated optical chip 1110a and a Faraday rotator (45°) 1155 shared between multiple (three shown) beams. Optionally, the Faraday rotator can be divided into more than two separate rotators, as many as one rotator for each beam, but a shared rotator has advantages in cost and compactness. Materials other than silicon, such as glass or fused quartz, can be used for the aspheric lens array substrate 1102. Generally, a lens substrate 1102 with a high refractive index is preferred. The optical signal from the PSR group 1120 passes through the Faraday rotator 1155 and proceeds to the corresponding group in the parallel IPC1030 (type I or type II) of the second integrated optical chip 1110b.

[0152] In some embodiments, a device using multiple beams (such as Fig.12 1200) wherein a single aspheric lens and a Faraday rotator are shared. In this variation, multiple field points are imaged by a single lens and a Faraday rotator, making it possible to reduce the size of both. In some embodiments, Fig.12 The multi-beam device 1200 includes angled emitters or couplers that couple the PSRs to free space, and in some embodiments, the integrated optical chip includes a curved facet to improve performance. "Curved facet" means that the individual channels of the emitters are aligned along the optical axis ( Fig.12 The angled emitters are used to shift the optical axis (left / right) of the lens to match any field curvature present in the lens system. "Angled emitters" means that the individual channels of the emitters are tilted relative to the optical axis to better match the chief ray angle of the light beam incident on them. In one embodiment, reasonable performance can be achieved for 9 channels with a spacing of 10um and a span of + / -40um using angled emitters. In the same implementation, an embodiment also provided with a curved surface can extend reasonable performance to + / -80um for 17 channels without significantly increasing the occupied area.

[0153] As in the embodiments described above, the device 1200 includes a first integrated optical chip 1210a and includes a PSR 1220 group for multiple beams. In some embodiments, the surface 1211a of the first integrated optical chip 1210a is curved. A single silicon aspheric converging lens 1202 is used between the first integrated optical chip 1210a and a single Faraday rotator (45°) 1255 shared by the multiple beams (three are shown). Materials other than silicon, such as glass or fused quartz, can be used for the aspheric converging lens 1202. Generally, a converging lens 1202 with a high refractive index is preferred. The optical signal from the PSR group 1220 passes through the Faraday rotator 1255 and proceeds to a corresponding group in a parallel IPC 1230 (type I or type II) of a second integrated optical chip 1210b, which may or may not have a curved surface 1211b.

[0154] In some embodiments, a device that uses a single integrated optical chip to transmit and receive optical signals can be implemented, such as Fig.13 The apparatus 1300 of claim 1300 wherein a reflector is used to reflect the optical signal back through the Faraday rotator. This embodiment is similar to Figure 3 or Fig. 9 An aspheric lens variation of an embodiment of the invention is "folded" in the middle of a Faraday rotator using a reflector and in which the PSR and IPC are offset on the same integrated optical chip.

[0155] As with the embodiments described above, the device 1300 includes an integrated optical chip 1310, and includes a PSR 1320. A single silicon aspheric converging lens 1302 is used between the integrated optical chip 1310 and a single Faraday rotator (22.5°) 1355. Materials other than silicon, such as glass or fused quartz, may be used for the aspheric converging lens 1302. Generally, converging lenses 1302 having a high refractive index are preferred. The Faraday rotator of this and other reflective embodiments has an appropriate thickness to produce the desired rotation of 22.5° after a single pass, and may include rare earth doped iron garnet. Where desired, materials such as Fig.161354. The optical signal from the converging lens 1302 passes through the Faraday rotator 1355 to obtain a total of 22.5° rotation (single pass) of the rotated polarization state, then reflects from the reflector 1357 and passes back through the Faraday rotator, obtaining an additional 22.5° to accumulate a total of 45° of polarization state rotation before passing through the converging lens 1302 again. The optical signal returning from the converging lens 1302 to the integrated optical chip 1310 enters the IPC 1330, which is integrated in the integrated optical chip 1310 at a position offset from the PSR 1320. The PSR 1320 and the IPC 1330 are positioned so that the optical signal emitted by the PSR 1320 passes through the converging lens 1302, the Faraday rotator 1355, and then is reflected by the reflector 1357 back through the Faraday rotator 1355 and the converging lens 1302 to enter the IPC 1330, and vice versa.

[0156] In some embodiments, reflector 1357 is a metal or dielectric coating with high reflectivity applied directly to the back surface of Faraday rotator 1355. Since the same length of Faraday rotator material is used twice, the same amount of polarization rotation can be achieved with half the length of Faraday rotator. In some embodiments, the thickness of the Faraday rotator is 400um. In some embodiments, such as Fig.16 Embodiments in which separate reflectors or mirrors may be employed, but typically exhibit slightly lower performance.

[0157] although Fig.13 and below Figures 14 to 18 The illustrated embodiments are described as including PSRs and IPCs on a single integrated optical chip, but it should be understood that the PSRs and IPCs of all the embodiments described herein may be integrated into any number of appropriately positioned integrated optical chips, which may be separate or shared with any number and combination of PSRs and IPCs, and further, which may or may not be integrated on a common substrate.

[0158] In such Fig.14 In the embodiment of the device 1400 shown, a method such as Fig.13 The design shown, but instead of separate lens and Faraday rotator arrangements, the lens and Faraday rotator are bonded to each other. In such an embodiment, wafer-level manufacturing such as single-piece active alignment assembly techniques can be used to bond the lens and Faraday rotator.

[0159] In some embodiments, due to the difference in refractive index, the AR coating is deposited between the lens (n=3.46 for Si) and the Faraday rotator (n=2.2 to 2.5).

[0160] As with the embodiments described above, the device 1400 includes an integrated optical chip 1410, and includes a PSR 1420. A single silicon aspheric converging lens 1402 is used between the integrated optical chip 1410 and a single Faraday rotator (22.5°) 1455 bonded to the single silicon aspheric converging lens 1402. Materials other than silicon, such as glass or fused quartz, may be used for the aspheric converging lens 1402. Generally, converging lenses 1402 having a high refractive index are preferred. The Faraday rotator of this and other reflective embodiments has an appropriate thickness to produce the desired 22.5° rotation after a single pass, and may include rare earth doped iron garnet. Where desired, a material such as Fig.16 14. The optical signal passes through the Faraday rotator 1455 from the converging lens 1402 to obtain a total of 22.5° of rotation of the polarization state, and then reflects from the reflector 1457 and passes back through the Faraday rotator, obtaining an additional 22.5° to achieve a total of 45° of polarization state rotation before passing through the converging lens 1402 again. The optical signal returning from the converging lens 1402 to the integrated optical chip 1410 enters the IPC 1430, which is integrated in the integrated optical chip 1420 at a position offset from the PSR 1420. The PSR 1420 and the IPC 1430 are positioned so that the optical signal emitted by the PSR 1420 passes through the converging lens 1402, the Faraday rotator 1455, and then is reflected by the reflector 1457 back through the Faraday rotator 1455 and the converging lens 1402 to enter the IPC 1430. Or vice versa.

[0161] In some embodiments, a device using multiple beams (such as Fig.15 1500) in which a single aspheric lens bonded to a Faraday rotator is shared. In this variation, multiple field points are imaged through a single lens bonded to a Faraday rotator, reducing the size of both, and halving the length of the Faraday rotator by virtue of the beam passing through the Faraday rotator twice due to the reflector. The device supports multiple channels (two shown) by connecting the PSR pair and the IPC pair on both sides of the central axis.

[0162] As with the embodiments described above, the device 1500 includes an integrated optical chip 1510 and includes a group of PSRs 1520 for multiple beams. A single aspheric converging lens 1502 is used between the integrated optical chip 1510 and a single Faraday rotator (22.5°) 1455 that is coupled to the single aspheric converging lens 1502 and shared between multiple beams (two are shown). Where necessary, an external permanent magnet or electromagnet 1550 is used, except that, for example, in the case of a latching type Faraday rotator, no external magnet is required. A reflector 1557 is fixed to the side of the Faraday rotator 1555 opposite to the converging lens 1502. The optical signal from the PSR group 1520 passes from the converging lens 1502 through the Faraday rotator 1555 to obtain a total polarization state rotation of 22.5°, then reflects from the reflector 1557 and passes back through the Faraday rotator to obtain an additional 22.5° for a total of 45° of polarization state rotation before passing through the converging lens 1502 again. The optical signal returning from the converging lens 1502 to the integrated optical chip 1510 enters the corresponding group in the parallel IPC 1530, which is integrated in the integrated optical chip 1510 at a position offset from the PSR 1520. The PSR 1520 and the IPC 1530 are positioned so that the optical signal emitted by the PSR 1520 passes through the converging lens 1502, the Faraday rotator 1555, and is reflected by the reflector 1557 back through the Faraday rotator 1559 and the converging lens 1502 to enter the IPC 1530, and vice versa.

[0163] In a similar Fig.13 In an embodiment, such as in Fig.16 In the device 1600, the lens, the Faraday rotator and the reflector can be separated from each other. Fig.16 In the illustrated embodiment, a separate reflector or mirror is used. While this is less desirable from a performance perspective, in certain manufacturing environments, reducing manufacturing cost or complexity may have a higher priority.

[0164] As in the above-described embodiments, the device 1600 includes an integrated optical chip 1610, and includes a PSR 1620. A single aspheric converging lens 1602 is used between the integrated optical chip 1610 and a single Faraday rotator (22.5°) 1655. Where necessary, an external permanent magnet or electromagnet 1650 is used, otherwise, such as in the case of a latching type Faraday rotator, no external magnet is required. A reflector 1657 is located on the opposite side of the Faraday rotator 1655 from the converging lens 1602 and is separated from the Faraday rotator 1655. The optical signal from the PSR 1520 group passes from the converging lens 1602 through the Faraday rotator 1655 to obtain a total polarization state rotation of 22.5° rotation (single pass), then reflects from the reflector 1657 and passes back through the Faraday rotator, obtaining an additional 22.5° for a total of 45° of polarization state rotation before passing through the converging lens 1602 again. The optical signal returning from the converging lens 1602 to the integrated optical chip 1610 enters the IPC 1630, which is integrated in the integrated optical chip 1010 at a position offset from the PSR 1620. The PSR 1620 and the IPC 1630 are positioned so that the optical signal emitted by the PSR 1620 passes through the converging lens 1602, the Faraday rotator 1655, and is reflected by the reflector 1657 back through the Faraday rotator 1655 and the converging lens 1602 to enter the IPC 1630, and vice versa.

[0165] It should be understood that due to the working mode of the PSR and IPC of the embodiments described above, the PSR and IPC in any PSR-IPC pair can be interchangeable. In these embodiments, a TE optical signal can be emitted from an IPC with a polarization (such as 45°), and the Faraday rotator causes the polarization of the optical signal to reach 90° before being received by the PSR and transmitted as TE through the second component side port of the PSR. In the opposite direction, the TE optical signal entering the PSR is emitted at 90° and then rotated to 135° by the Faraday rotator, after which it enters the IPC and is discarded or rerouted as TE through the other component side port of the IPC.

[0166] Fig.17 and Fig.18 An example of on-chip components is shown for a reflector embodiment similar to the embodiments described above.

[0167] exist Fig.17In the illustrated on-chip assembly 1700, the assembly of reflector 1757, converging lens 1702, and Faraday rotator 1755 is located on top of a photonics die 1710 in a lower portion or etched cavity, adjacent to a facet 1711 of the photonics die 1710, and bonded to the photonics die 1710 using an adhesive or solder 1715. The facet 1711 of the photonics die 1710 corresponds to the facet of an integrated optical chip in which the PSR and IPC are integrated as described above.

[0168] exist Fig.18 In the illustrated on-chip assembly 1800, the assembly of reflector 1857, converging lens 1802, Faraday rotator 1855 is located on top of a common substrate or interposer 1880, adjacent to face 1811 of photonic wafer 1810, and bonded to the common substrate or interposer 1880 with adhesive or solder 1815. Photonic wafer 1810 is also bonded to the common substrate or interposer 1880 with adhesive or solder 1815. Face 1811 corresponds to the face of the integrated optical chip in which the PSR and IPC are integrated as described above.

[0169] Just combine Figures 13 to 18 In terms of the performance of the illustrated reflective embodiments, in one case, the normal incidence emitter is able to achieve multi-channel performance over a field of >0.94 Strehl at + / -160μm (16 channels at 10μm pitch or 8 channels at 20μm pitch), and the footprint excluding the PSR region is within 1.2x 0.5mm (200x200μm per channel). In a variant where the emitter is angled relative to the focal plane and a larger chip-lens distance is used (an additional 0.6mm), by doubling the number of channels, i.e., 32 channels at 10μm pitch or 16 channels at 20μm pitch, the field can be doubled to + / -320μm with nominal performance only reduced to 0.89 Strehl.

[0170] In some embodiments, one of the pairs of integrated polarization devices (e.g., 330, 1030, 1130, 1230, 1330, 1430, 1530, 1630) can be omitted entirely and replaced with a coupler or transmitter coupled to the integrated chip, while the IPC serves as the remaining integrated polarization device. Fig.19 This variation is shown in Figure 3 and Fig. 9A similar embodiment, but with only one integrated polarization device. In this embodiment 1900, the IPC 1930 on the integrated chip 1901a is used to receive the original TE optical signal on one of its component side ports 1910a, and then convert it to a -45° polarized optical signal, which is then transmitted through the lens 1902a toward the Faraday rotator 1955. The Faraday rotator 1955 (and mirror, in the folded embodiment) rotates the polarization of the optical signal to 0° or TE, after which it passes through the second lens 1902b (or the same lens, in the folded implementation example) and is collected by the coupler or transmitter on the receiving port of the waveguide 1909a of the integrated chip 1901b. In the opposite direction, the TE (0°) optical signal emitted from waveguide 1909a to free space passes through the second lens 1902b, encounters the Faraday rotator 1955, exits with a polarization of 45°, passes through lens 1902a, and when entering the polarization side port of IPC 1930, is discarded or rerouted as "TE" through another component side port 1920b, or is simply discarded regardless of whether IPC1930 has a second component side port.

[0171] In some embodiments, an additional polarization device can be located on any component side port or waveguide (e.g., port or waveguide 9100a, 9100b, 9009a, 9009b, 1910a, 1910b, or 1909a) to substantially attenuate light in these waveguides that is not in TE mode. For example, the polarization device can be a PSR whose component side TE port faces the isolator or circulator structure and whose polarization side port forms a new input or output coupled to the isolator or circulator (e.g., 9000 or 1900) in the corresponding integrated chip. In these embodiments, any TM mode optical signal intercepted by the PSR on the way to the isolator or circulator will be directed away from the isolator or circulator to reach the component side "TM as TE" port of the PSR and can be discarded.

[0172] While particular implementations and applications of the present invention have been shown and described, it will be understood that the invention is not limited to the precise construction and composition disclosed herein and that various variations, changes and modifications will be apparent from the foregoing description without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. An integrated photonic system, comprising: at least one integrated chip; a first integrated polarization device integrated in the at least one integrated chip, configured to transmit a first incident light signal received through a first component side port of the first integrated polarization device as a first polarized light signal into free space through a polarization side port of the first integrated polarization device; as well as at least one Faraday rotator, configured to receive the first polarized light signal, rotate the polarization of the first polarized light signal, and generate a rotated first polarized light signal propagating along a first direction; and for receiving a second polarized optical signal having the same polarization as the rotated first polarized optical signal and propagating in a second direction opposite to the first direction, rotating the polarization of the second polarized optical signal and generating a rotated second polarized optical signal; The first integrated polarization device is configured to receive the rotated second polarization light signal through the polarization side port of the first integrated polarization device and guide the rotated second polarization light signal away from the first component side port of the first integrated polarization device.

2. The integrated photonic system according to claim 1 further comprises a second integrated polarization device integrated in the at least one integrated chip, for transmitting the rotated first polarized light signal received through the polarization side port of the second integrated polarization device as an output light signal through the component side port of the second integrated polarization device, and for transmitting the second incident light signal received through the component side port as the second polarized light signal through the polarization side port toward the at least one Faraday rotator into free space.

3. The integrated photonic system of claim 2, wherein the at least one Faraday rotator comprises a first 45° Faraday rotator and a second 45° Faraday rotator, the first integrated polarization device comprises a first polarization beam splitter rotator (PSR), and the second integrated polarization device comprises a second PSR, the integrated photonic system further comprising: a first lens between the first PSR and the at least one Faraday rotator for collimating the first polarized light signal; a polarizer between the first 45° Faraday rotator and the second 45° Faraday rotator, oriented at 45° relative to the polarization of the first polarized optical signal in the same direction of rotation as the rotation applied by the first 45° Faraday rotator; as well as A second lens between the at least one Faraday rotator and the second PSR is used to focus the rotated first polarized light signal.

4. An integrated photonic system according to claim 2, wherein the at least one Faraday rotator comprises a 45° Faraday rotator, and the second integrated polarization device comprises an integrated polarization controller (IPC) for generating the output optical signal having a polarization different from the polarization of the rotated first polarized optical signal, and for generating the second polarized optical signal from the second incident optical signal, the second incident optical signal having the same polarization as the output optical signal.

5. The integrated photonic system of claim 4, wherein the first integrated polarization device is configured to substantially discard the rotated second polarization optical signal received by the first integrated polarization device.

6. The integrated photonic system of claim 4, wherein the first integrated polarization device is configured to direct the rotated second polarization optical signal received by the first integrated polarization device substantially through the second component-side port of the first integrated polarization device.

7. The integrated photonic system of claim 4, wherein the IPC comprises: a polarization side port facing the 45° Faraday rotator; at least one component side port opposite to the polarization side port of the IPC; a polarization beam splitter rotator PSR comprising a first port, a second port and a third port, the PSR being coupled via the first port of the PSR through the polarization side port of the IPC; a first set of waveguides coupled to the second port and the third port of the PSR; a first phase shifter coupled along a first waveguide of the first set of waveguides; as well as A first beamsplitter comprising a first set of ports and a second set of ports, the first beamsplitter being coupled to the PSR through the first set of waveguides and via the first set of ports of the first beamsplitter, and being coupled through at least one of the second set of ports of the first beamsplitter via the at least one component-side port of the IPC.

8. The integrated photonic system of claim 4, further comprising a lens between the first integrated polarization device and the 45° Faraday rotator.

9. An integrated photonic system according to claim 4, wherein the first integrated polarization device is one of a plurality of first integrated polarization devices included in the integrated photonic system, wherein the IPC is one of a plurality of IPCs included in the integrated photonic system, and wherein the 45° Faraday rotator comprises a shared 45° Faraday rotator for rotating the polarization of optical signals transmitted between the plurality of first integrated polarization devices and the plurality of IPCs.

10. The integrated photonic system of claim 9, further comprising a lens array between the plurality of first integrated polarization devices and the common 45° Faraday rotator.

11. The integrated photonic system of claim 9, further comprising a single common lens between the plurality of first integrated polarization devices and the common 45° Faraday rotator.

12. An integrated photonic system according to claim 11, wherein each of the plurality of first integrated polarization devices and each of the plurality of IPCs are angled relative to the focal plane of the single common lens, and the at least one integrated chip includes a curved surface near the location where the first integrated polarization device and the IPC are integrated.

13. The integrated photonic system of claim 2, wherein the at least one Faraday rotator comprises a 22.5° Faraday rotator, and wherein the integrated photonic system further comprises: a lens between the first integrated polarization device and the 22.5° Faraday rotator; and a reflector located on a side of the 22.5° Faraday rotator opposite to the lens, for reflecting an optical signal passing through the 22.5° Faraday rotator from the lens back into the 22.5° Faraday rotator toward the lens; The second integrated polarization device includes an integrated polarization controller (IPC) for generating the output optical signal having a polarization different from the polarization of the rotated first polarized optical signal, and for generating the second polarized optical signal from the second incident optical signal, wherein the second incident optical signal has the same polarization as the output optical signal.

14. The integrated photonic system of claim 13, wherein the first integrated polarization device is configured to substantially discard the rotated second polarization optical signal received by the first integrated polarization device.

15. The integrated photonic system of claim 13, wherein the first integrated polarization device is configured to direct the rotated second polarization optical signal received by the first integrated polarization device substantially through a second component-side port of the first integrated polarization device.

16. The integrated photonic system of claim 13, wherein the IPC comprises: a polarization side port facing the 22.5° Faraday rotator; at least one component side port opposite to the polarization side port of the IPC; a polarization beam splitter rotator PSR comprising a first port, a second port and a third port, the PSR being coupled via the first port of the PSR through the polarization side port of the IPC; a first set of waveguides coupled to the second port and the third port of the PSR; a first phase shifter coupled along a first waveguide of the first set of waveguides; as well as A first beamsplitter comprising a first set of ports and a second set of ports, the first beamsplitter being coupled to the PSR through the first set of waveguides and via the first set of ports of the first beamsplitter, and being coupled through at least one of the second set of ports of the first beamsplitter via the at least one component-side port of the IPC.

17. An integrated photonic system according to claim 13, wherein the first integrated polarization device is one of a plurality of first integrated polarization devices included in the integrated photonic system, wherein the IPC is one of a plurality of IPCs included in the integrated photonic system, and wherein the 22.5° Faraday rotator comprises a shared 22.5° Faraday rotator for rotating the polarization of optical signals transmitted between the plurality of first integrated polarization devices and the plurality of IPCs.

18. An integrated photonic system according to claim 17, wherein the lens includes a single common lens between the plurality of first integrated polarizers and the common 22.5° Faraday rotator, and wherein each of the plurality of first integrated polarizers and each of the plurality of IPCs are angled relative to the focal plane of the single common lens, and the at least one integrated chip includes a curved surface proximate to the location where the first integrated polarizer and the IPC are integrated.

19. The integrated photonic system of claim 13, wherein the lens, the reflector, and the 22.5° Faraday rotator are combined together to form a single lens-rotator-reflector assembly.

20. The integrated photonic system of claim 19, wherein the lens-rotator-reflector assembly is mounted on one or more of the at least one integrated chip or on a common substrate on which the at least one integrated chip is mounted.

21. The integrated photonic system of claim 1, wherein the at least one Faraday rotator comprises a 22.5° Faraday rotator, and wherein the integrated photonic system further comprises: a lens between the first integrated polarization device and the 22.5° Faraday rotator; and a reflector located on a side of the 22.5° Faraday rotator opposite to the lens, for reflecting an optical signal passing through the 22.5° Faraday rotator from the lens back into the 22.5° Faraday rotator toward the lens; The first integrated polarization device comprises an IPC for generating the first polarized light signal having a polarization different from that of the first incident light signal.

22. The integrated photonic system of claim 21, wherein the IPC is configured to substantially discard the rotated second polarization optical signal received by the IPC.

23. The integrated photonic system of claim 21, wherein the IPC is configured to direct the rotated second polarization optical signal received by the IPC substantially through a second component-side port of the IPC.

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