Photon mixing receiver and modulator circuit and method

Abstract

Photonics has become a main technical solution for dealing with bandwidth demand increase in the communication field, and the technology is still continuously developed. Thus, photonic communications are developing towards a coherent modulation format to further increase capacity by encoding information in the phase and amplitude of the optical signal. While coherent optical transmitters and receivers are more complex than switch-type transmitters and receivers, manufacturing the optical elements with monolithic optical elements and photonic integrated circuits can reduce the cost of coherent optical components. Further, external modulation using a phase modulator, an amplitude modulator, or a combination of both, can increase modulation bandwidth relative to a directly modulated laser, thereby improving data transmission rate. The invention provides a novel photon mixing optical path and an external modulator. The novel photon mixing optical path and the external modulator are compatible with a photon integrated circuit manufacturing technology and a monolithic integration technology.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This patent application claims the priority benefit of PCT / CA2024 / 051011 filed on July 30, 2024.

[0002] This patent application claims the benefit of priority to U.S. Provisional Patent Application No. 63 / 517,005, filed on August 1, 2023, the entire contents of which are incorporated herein by reference.

[0003] This patent application claims the benefit of priority to U.S. Provisional Patent Application 63 / 571,651, filed on March 29, 2024.

[0004] This patent application claims the benefit of priority to U.S. Provisional Patent Application 63 / 657,253, filed on June 6, 2024. Technical Field

[0005] The present invention relates to photonic circuits, and more particularly to photonic hybrid circuits for coherent optical receivers and photonic modulators for optical transmitters. Background Art

[0006] From sensing, biomedical sensing, to quantum computing, quantum sensing and telecommunications, photonics has been widely used and has become a dominant technology solution and continues to develop and improve. In communications, streaming media, mobile data traffic and cloud computing have an increasing demand for bandwidth. To meet this demand, photonic communications are moving towards coherent modulation formats to further increase capacity. Compared with traditional on-off keying modulation formats in current optical communication networks, coherent modulation formats encode information in the phase and amplitude of the optical signal.

[0007] However, coherent optical transmitters and coherent optical receivers are more complex than their switch counterparts. Therefore, it would be beneficial to provide such systems with optical elements and photonic integrated circuits employing the same, as these offer the potential to reduce the cost of coherent photonic components by utilizing hybrid and / or monolithic integration with semiconductor-level manufacturing cost profiles and techniques.

[0008] Therefore, the inventors have created a novel photonic hybrid circuit that is compatible with this photonic integrated circuit manufacturing technology, with the potential for monolithic integration of a complete coherent receiver. The novel photonic hybrid circuit also supports wafer-level testing before die tapping to further enhance the manufacturing process and reduce costs.

[0009] In addition, external modulation of continuous wave (CW) lasers can provide increased modulation bandwidth relative to that of directly modulated lasers to further increase data transmission. Such external modulators can be phase modulators or amplitude modulators or a combination thereof. However, in most materials, the speed mismatch between the optical and electrical signals must be compensated to achieve the desired bandwidth and increased device length to reduce the drive voltage. In silicon photonics, this requires slowing down the optical signal. Therefore, it would be beneficial to achieve this without increasing the optical losses of the modulator.

[0010] Other aspects and features of the present invention will become apparent to those of ordinary skill in the art after reading the following description of specific embodiments of the present invention in conjunction with the accompanying drawings. Summary of the invention

[0011] An object of the present invention is to alleviate limitations of the prior art associated with photonic circuits, and more specifically, to alleviate limitations associated with photonic hybrid circuits for coherent optical receivers and photonic modulators for optical transmitters.

[0012] According to an embodiment of the present invention, there is provided a photonic circuit, comprising: an adiabatic coupler having a pair of input ports and a pair of output ports; a first coupler having an input port coupled to an output port of a pair of output ports of the adiabatic coupler; a second coupler having an input port coupled to the other of the pair of output ports of the adiabatic coupler; and The third coupler has a pair of input ports and a pair of output ports; wherein, An output port of the pair of output ports of a third coupler is coupled to the other input port of the first coupler; The other of the pair of output ports of the third coupler is coupled to the other input port of the second coupler; A pair of output ports of the first coupler are coupled to a first balanced photodetector; and A pair of output ports of the second coupler are coupled to a second balanced photodetector.

[0013] According to an embodiment of the present invention, a method for receiving photon data is provided, comprising: A photonic circuit is provided comprising a pair of photonic hybrid circuits, each photonic hybrid circuit comprising: an adiabatic coupler having a pair of input ports and a pair of output ports; a first coupler having an input port coupled to an output port of a pair of output ports of the adiabatic coupler; a second coupler having an input port coupled to the other of the pair of output ports of the adiabatic coupler; and The third coupler has a pair of input ports and a pair of output ports; wherein, An output port of the pair of output ports of a third coupler is coupled to the other input port of the first coupler; The other of the pair of output ports of the third coupler is coupled to the other input port of the second coupler; A pair of output ports of the first coupler are coupled to a first balanced photodetector; and A pair of output ports of the second coupler are coupled to a second balanced photodetector; providing a splitter coupled to a laser that emits at a predetermined wavelength with a predetermined polarization, wherein a first output of the splitter is coupled to an input port of a pair of input ports of an adiabatic coupler within a photonic hybrid circuit of the pair of photonic hybrid circuits, and a second output of the splitter is coupled to an input port of a pair of input ports of an adiabatic coupler within another photonic hybrid circuit of the pair of photonic hybrid circuits; A polarization splitter and rotator (PSR) circuit is provided coupled to a network for receiving an optical signal of a predetermined wavelength, wherein a first output of the PSR circuit is split from an optical signal received by the PSR circuit having a predetermined polarization, and the first output of the PSR circuit is coupled to an input port of a third coupler of a photonic hybrid circuit in a pair of photonic hybrid circuits, and a second output of the PSR circuit is split from a received optical signal having a polarization orthogonal to the predetermined polarization and is rotated to the predetermined polarization before becoming a second output of the PSR circuit, and the second output of the PSR circuit is coupled to an input port of a third coupler in the other photonic hybrid circuit in the pair of photonic hybrid circuits.

[0014] According to an embodiment of the present invention, there is provided a photonic circuit, comprising: an adiabatic coupler having a pair of input ports and a pair of output ports; a first coupler having an input port coupled to an output port of a pair of output ports of the adiabatic coupler; a second coupler having an input port coupled to the other of the pair of output ports of the adiabatic coupler; and The third coupler has a pair of input ports and a pair of output ports; wherein, An output port of the pair of output ports of a third coupler is coupled to the other input port of the first coupler; and The other of the pair of output ports of the third coupler is coupled to the other input port of the second coupler.

[0015] According to an embodiment of the present invention, there is provided a device, comprising: Optical waveguides; A traveling wave electrode for causing a phase shift of an optical signal propagating in an optical waveguide, the traveling wave electrode comprising a plurality of contacts arranged along a section of the optical waveguide; wherein, The optical waveguide has a periodic offset along the length of the segment of the optical waveguide from an overall path of the optical waveguide by a mathematical function, the overall path being defined by another mathematical function over the length of the segment of the optical waveguide; and The period of the periodic shift is defined according to the interval between adjacent pairs of contacts of the plurality of contacts.

[0016] Other aspects and features of the present invention will become apparent to those of ordinary skill in the art after reading the following description of specific embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

[0018] FIG1 shows a polarization diversity coherent receiver according to the prior art;

[0019] FIG2 shows a photonic hybrid circuit for a coherent receiver according to the prior art;

[0020] Figure 3 A photonic hybrid circuit for a coherent receiver according to an embodiment of the present invention is shown;

[0021] Figure 4 A polarization diversity coherent receiver according to an embodiment of the present invention is shown. Figure 3 The photonic hybrid circuit of the present invention is shown;

[0022] Figure 5 A photonic hybrid circuit for a coherent receiver according to an embodiment of the present invention is shown;

[0023] Figure 6 A photonic hybrid circuit for a coherent receiver according to an embodiment of the present invention is shown; and

[0024] Figure 7 A phase matching method for a traveling wave modulator according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0025] The present invention relates to photonic circuits, and in particular to photonic hybrid circuits for coherent optical receivers and photonic modulators for optical transmitters.

[0026] The subsequent description provides only representative embodiments, and is not intended to limit the scope, applicability or configuration of the present invention. On the contrary, the subsequent description of the embodiment will provide an enabling description for implementing one or more embodiments of the present invention to those skilled in the art. It should be understood by those skilled in the art that various changes can be made to the functions and arrangements of the elements without departing from the scope of the present invention as set forth in the claims. Therefore, the embodiment is an example or implementation of the present invention, rather than the only implementation. Various expressions "one embodiment", "embodiment" or "some embodiments" do not necessarily refer to the same embodiment. Although the various features of the present invention can be described in the context of a single embodiment, these features can also be provided separately or in any suitable combination. On the contrary, although the present invention can be described in the context of a single embodiment for clarity, the present invention can also be implemented in a single embodiment or any combination of embodiments.

[0027] References in the specification to "one embodiment," "embodiments," "some embodiments," or "other embodiments" mean that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention, but not necessarily in all embodiments. The words and terminology used herein should not be construed as limiting, but are used for descriptive purposes only. It should be understood that where a claim or specification refers to "a" or "an" element, such reference should not be construed as meaning that there is only one of that element. It should be understood that where the specification states that a component feature, structure, or characteristic "may," "might," "could," or "can" be included, that particular component, feature, structure, or characteristic is not required to be included.

[0028] References to terms such as "left," "right," "top," "bottom," "front," and "back" are intended to be used to illustrate the orientation of a particular feature, structure, or element within the drawings of embodiments of the present invention. Obviously, such directional terms have no specific meaning with respect to actual use of the device, as the device can be used in a variety of orientations by one or more users.

[0029] Reference to the terms "including", "comprising", "consisting of" and grammatical variations thereof do not exclude the addition of one or more components, features, steps, components or combinations thereof, and these terms should not be interpreted as specifying components, features, steps or components. Similarly, "consisting essentially of" and grammatical variations thereof, when used herein, should not be interpreted as excluding additional components, steps, features, components or combinations thereof, but the additional features, components, steps, components or combinations thereof do not substantially change the basic and novel nature of the claimed composition, apparatus or method. If the description or claims mention "additional" elements, the presence of more than one additional element is not excluded.

[0030] As used herein, a "two-dimensional" waveguide (also referred to as a 2D waveguide or planar waveguide) may refer to, but is not limited to, an optical waveguide that supports propagation of optical signals within a specific wavelength range and does not guide lateral propagation of the optical signal relative to the propagation direction of the optical signal.

[0031] As used herein, a “three-dimensional” waveguide (also referred to as a 3D waveguide, channel waveguide, or simply a waveguide) may refer to, but is not limited to, an optical waveguide that supports propagation of optical signals within a specific wavelength range, and that guides the lateral propagation of the optical signal relative to the propagation direction of the optical signal.

[0032] As used herein, "photonic integrated circuit" (PIC) may refer to, but is not limited to, a circuit formed by monolithically integrating multiple integrated optical devices onto a common substrate, providing optical routing and processing functions. PICs are manufactured using wafer-level processing technology (e.g., CMOS manufacturing flow, MEMS processing flow, etc.).

[0033] As used herein, an "adiabatic coupler" may refer to, but is not limited to, an optical coupler that adiabatically converts a mode of an input optical waveguide into an even mode or an odd mode of two or more optical waveguides separated by a small gap. Thus, the adiabatic coupler may be, for example, a non-zero gap symmetrical directional coupler or a non-zero gap asymmetrical directional coupler.

[0034] In embodiments of the present invention, the inventors may refer to the term "hybrid integration". In some embodiments of the present invention, this may refer to, but is not limited to, "integrating" an optical element onto a substrate by attaching an optical element or another element physically integrated with the optical element to a substrate (platform) so that the optical element remains in place. Such attachment methods may include, but are not limited to, welding, epoxy resin, van der Waals forces, electrostatic attachment, magnetic attachment, physical interlocking, and friction. Therefore, in these embodiments of the present invention, the hybrid integrated optical element may be considered to be implemented in a manufacturing process parallel to other optical elements before being assembled together. The parallel manufacturing process may employ one or more processes selected from a combination including, but not limited to, liquid phase epitaxy (LPE), metal organic chemical vapor deposition (MOCVD), organometallic vapor phase epitaxy (OMVPE), selective area epitaxy, additive manufacturing processes, non-additive manufacturing processes, crystal growth, doping, induced damage, etching, doping, and deposition.

[0035] In other embodiments of the present invention, this may refer to, but is not limited to, integrating an optical component onto a substrate using an "integrated" approach that is different from the manufacturing methods and / or techniques used to form other optical components on the substrate. For example, this may be forming another optical component on a substrate using an LPE process, wherein the optical component on the substrate is formed by MOCVD, or vice versa. Alternatively, both the optical component and the other optical component may be formed using the same manufacturing method or combination of manufacturing methods. These manufacturing methods may use one or more processes selected from the group including but not limited to LPE, MOCVD, OMVPE, selective area epitaxy, additive manufacturing processes, subtractive manufacturing processes, non-additive manufacturing processes, crystal growth, doping, induced damage, etching, doping and deposition.

[0036] In embodiments of the present invention, the inventors refer to the terms "hybrid integration" and "hybrid integration". In some embodiments of the present invention, this may refer to, but is not limited to, "integrating" optical elements into a substrate by attaching optical elements or other elements physically integrated with optical elements to a substrate (platform) so that the optical elements remain in place. Such attachment means may include, but are not limited to, welding, epoxy resin, van der Waals forces, electrostatic attachment, magnetic attachment, physical locking, and friction. Therefore, in these embodiments of the present invention, other hybrid integrated optical elements may be considered to be implemented in a manufacturing process parallel to other optical elements before being assembled together. The parallel manufacturing process may adopt one or more processes including, but not limited to, the following combinations: liquid phase epitaxy (LPE), metal organic chemical vapor deposition (MOCVD), organometallic vapor phase epitaxy (OMVPE), selective area epitaxy, additive manufacturing processes, non-additive manufacturing processes, crystal growth, doping, induced damage, etching, doping, and deposition.

[0037] In embodiments of the present invention, the inventors refer to the terms "monolithic integration" and "monolithic integration". In some embodiments of the present invention, this may refer to, but is not limited to, "integrating" an optical element onto a substrate by forming the optical element directly on the substrate (platform). The optical element may be one of a series of optical elements formed on a substrate to form an optical element or optical circuit. These optical elements may be optical waveguides themselves, interconnected by optical waveguides, interconnected by other optical elements formed on the substrate in subsequent processing steps or stages, or interconnected via hybrid integration to other optical elements on the substrate. Therefore, in these embodiments of the present invention, these monolithically integrated optical elements (e.g., optical waveguides) can adopt one or more manufacturing processes selected from the group including but not limited to: liquid phase epitaxy (LPE), metal organic chemical vapor deposition (MOCVD), organic metal vapor phase epitaxy (OMVPE), selective area epitaxy, photolithography, direct writing, ion beam milling, additive manufacturing processes, non-additive manufacturing processes, crystal growth, doping, induced damage, chemical etching, reactive ion etching (RIE), plasma etching, sputter etching, ion beam assisted etching, reactive ion beam etching, lift-off and deposition.

[0038] As used herein, "ceramic" may refer to, but is not limited to, inorganic non-metallic solid materials containing metal, non-metal or metalloid atoms held primarily in ionic and covalent bonds. Such ceramics may be crystalline materials such as oxides, nitrides or carbides, elements such as carbon or silicon, and amorphous materials. Exemplary ceramics may include high temperature ceramics or high temperature co-fired ceramics such as aluminum oxide (Al2O3), zirconium oxide (ZrO2) and aluminum nitride (AlN) or low temperature co-fired ceramics (LTCC). LTCC may be formed from a glass-ceramic combination.

[0039] As used herein, "metal" or "alloy" may refer to, but is not limited to, materials with good electrical and thermal conductivity. Metals are generally ductile, fusible, and plastic. As used herein, metals may refer to elements such as gold, silver, copper, aluminum, iron, etc. And alloys as used herein refer to combinations of metals such as bronze, stainless steel, steel, etc.

[0040] As used herein, "polymer" may refer to, but is not limited to, a macromolecule or polymer composed of many repeating subunits. Such polymers may be natural and synthetic, and are typically produced via the polymerization of a variety of monomers. Polymers can provide unique physical properties through their macromolecular mass, including toughness, viscoelasticity, and ease of forming glass and semi-crystalline structures rather than crystalline structures.

[0041] As used herein, "glass" may refer to, but is not limited to, a non-crystalline amorphous solid. Glass may be, for example, fused quartz, silica, soda-lime glass, borosilicate glass, lead glass, aluminosilicate glass. Glass may include other inorganic and organic materials, including metals, aluminates, phosphates, borates, chalcogenides, fluorides, germanates (glasses based on GeO2), tellurites (glasses based on TeO2), antimonates (glasses based on Sb2O3), arsenates (glasses based on As2O3), titanates (glasses based on TiO2), tantalates (glasses based on Ta2O5), nitrates, carbonates, plastics, and acrylic acid.

[0042] Embodiments of the present invention may be implemented in one or more semiconductor materials (semiconductors), for example, by LPE, MOCVD or OMVPE. One or more semiconductors may include, but are not limited to, III-V semiconductors, II-VI semiconductors, IV semiconductors, and IV-V-VI semiconductors. Examples of III-V semiconductors may include AlP, AlN, AlGaSb, AlGaAs, AlGaInP, AlGaN, AlGaP, GaSb, GaAsP, GaAs, GaN, GaP, InAlAs, InAlP, InSb, InGaSb, InGaN, GaInAlAs, GaInAlN, GaInAsN, GaInAsP, GaInAs, GaInP, InN, InP, InAs, InAsSb, InGaAsP, and AlInN. Examples of II-VI semiconductors may include ZnSe, HgCdTe, ZnO, ZnS, and CdO. Examples of IV semiconductors may include Si, Ge, and strained silicon. IV-V-VI semiconductors may be GeSbTe.

[0043] In many cases, such semiconductors allow monolithic integration of passive optical waveguides with active optical components such as light emitting diodes, semiconductor optical amplifiers, laser diodes (LDs) distributed feedback laser diodes, external cavity laser diodes (ECLs) photodetectors (PDs), and avalanche photodetectors (APDs). For example, InGaAsP semiconductors support PDs, LDs, or ECLs, etc., operating in the conventional infrared telecommunication windows known as the S-band (1460-1530 nm), C-band (1530-1565 nm), and L-band (1565-1625 nm).

[0044] In an embodiment of the present invention, the platform or substrate used for semiconductor growth and processing can be the semiconductor material itself, such as GaAs or InP, or in other embodiments of the present invention can be other materials, such as silicon, germanium, ceramics, glass or polymer.

[0045] In an embodiment of the present invention, the platform or substrate used for integration can be a silicon substrate, wherein one or more optical waveguides utilize a silicon nitride core with an upper and lower cladding layer of silicon oxide, a waveguide structure on the platform. Alternatively, one or more optical waveguides can also use a silicon core with an upper and lower cladding layer of silicon nitride. Optionally, in other embodiments of the present invention, the upper cladding layer can be omitted.

[0046] Embodiments of the present invention may be implemented with one or more silicon-on-insulator (SOI) optical waveguides, such as air-encapsulated Si3N4-SiO2, SiO2-Si3N4-SiO2, SiO2-Ge:SiO2-SiO2, or Si-SiO2. Embodiments of the present invention may be implemented with one or more waveguides, such as ion-exchanged glass waveguides, ion-implanted glass waveguides, polymer-on-silicon waveguides, doped silicon waveguides, and polymer waveguides. Although not necessarily taking advantage of photonic integration, embodiments of the present invention may also be formed using optical fibers, free-space optical elements, and the like.

[0047] In the case where passive optical waveguides are used in hybrid integration with active optical elements such as LDs, ECLs, and PDs, these can be directly butt-coupled, or they can employ intermediate coupling optical elements such as ball lenses, spherical lenses, gradient refractive index (GRIN) lenses, etc., for free space coupling and / or photonic wire bonding, etc. Other waveguide structures can be employed, including vertical and / or lateral waveguide tapers, and the formation of micro-sphere lenses on the ends of the waveguides via laser and / or arc melting at the waveguide tips.

[0048] Embodiments of the present invention employing optical waveguides may employ waveguide cores embedded in upper and lower claddings, so-called buried waveguides, air cladding waveguides (i.e., cores with lower cladding and air elsewhere), rib waveguides, diffused waveguides, ridge or line waveguides, strip-loaded waveguides, slot waveguides, anti-resonant reflection optical waveguides (ARROW waveguides), photonic crystal waveguides, suspended waveguides, alternating layer stack geometries, sub-wavelength grating (SWG) waveguides, or enhanced waveguides (e.g., Si-SiO2-Polymer). Embodiments of the present invention may employ step-index waveguides, gradient-index waveguides, or hybrid-index waveguides (such as combining inverse step-index and gradient-index).

[0049] FIG. 1 shows a polarization diversity coherent receiver (PDCR) 100 according to the prior art. As shown, an optical signal (identified as data 110) received from an optical transmitter from an optical network to which the PDCR 100 is coupled is coupled to the PDCR 100 together with an optical local oscillator signal (laser 120). Since the optical signal data 110 comes from the optical network, its polarization is unknown and will change over time. Therefore, the data 110 is coupled to a polarization splitter-rotator (PSR) 130 so that the PSR 130 generates a pair of outputs, one of which is directly branched from the data 110 with a defined polarization, and the other output is branched and rotated to a defined polarization. Since the laser 120 is local and may be integrated within the PDCR 100, it transmits with a single polarization, where the defined polarization from the PSR 130 is the polarization of the laser 120. The optical local oscillator signal laser 120 is branched by a splitter 140.

[0050] One output from PSR 130 and one output from splitter 140 are each coupled to a first optical hybrid 150A, while another output from PSR 130 and another output from splitter 140 are each coupled to a second optical hybrid 150B.

[0051] In the first optical hybrid 150A, the first output 180A from the PSR 130 (including the data 110 signal) and the first output 170A from the splitter 140 (including the laser 120 signal) are combined to produce a pair of I outputs coupled to a first balanced photodetector pair (BPR) 160A and a pair of Q outputs coupled to a second BPR 160B. In the second optical hybrid 150B, the second output 180B from the PSR 130 (including the data 110 signal) and the second output 170B from the splitter 140 (including the laser 120 signal) are combined to produce a pair of I outputs coupled to a third BPR 160C and a pair of Q outputs coupled to a fourth BPR 160D.

[0052] The electrical outputs from the first through fourth BPRs 160A through 160D, respectively, are then combined to produce the data encoded within optical signal data 110 .

[0053] FIG2 shows a photonic hybrid circuit (optical hybrid 200) for a coherent receiver according to the prior art. Port LO is coupled to an optical local oscillator signal, such as the laser 120 in FIG1 , and port signal is coupled to received data, such as the data 110 in FIG1 . LO is coupled to a Y-junction 50:50 power splitter 210, which produces a pair of outputs with the same phase, and signal is coupled to a first 2×2 multimode interferometer (MMI) 240, which produces a pair of outputs with a 90° phase difference therebetween. Each output including an optical local oscillator signal is coupled to an input of a second 2×2 MMI 220 and a third MMI 230, respectively. Another input of the second 2×2 MMI 220 and another input of the third 230 are coupled to a pair of outputs of the first 2×2 MMI 220, respectively. Therefore, the output of the second 2×2 MMI 220 is a first and a second orthogonal signal Q n and Q p , and the output of the third 2×2 MMI 230 is the first and second in-phase signals I n and I p .

[0054] Figure 3 A photonic hybrid circuit for a coherent receiver according to an embodiment of the present invention is shown. A first image 300A shows a photonic hybrid circuit (optical hybrid 300) in which the Y-junction 50:50 power splitter 210 as shown in FIG. 2 is replaced by an adiabatic 3dB splitter 310. A second image 300B shows the mode evolution within the adiabatic 3dB splitter 310 for an optical signal coupled to each input port.

[0055] Figure 4 A polarization diversity coherent receiver (PDCR) 400 according to an embodiment of the present invention is shown. Figure 3 1. The PDCR 400 is similar in design and operation to the PDCR 100, except that first and second optical hybrids 410A and 410B are now employed instead of the first and second optical hybrids 150A and 150B. Each of the first and second optical hybrids 410A and 410B includes the optical hybrid 300. Therefore, the first optical hybrid 410A now has four input ports therein instead of the two input ports of the first optical hybrid 150A.

[0056] On one side of the first optical hybrid 410A, the first input port 430A is coupled to the first test point 420A, and the second input port 430B is coupled to the laser 120 via the splitter 470. On the other side of the first optical hybrid 410A, the third input port 440A is coupled to the second test point 420B, and the fourth input port 440B is coupled to the data 110 via the PSR 130.

[0057] On one side of the second optical hybrid 410B, the first input port 450A is coupled to the third test point 420C, and the second input port 450B is coupled to the laser 120 via the splitter 470. On the other side of the second optical hybrid 410B, the third input port 460A is coupled to the data 110 via the PSR 130, and the fourth input port 440B is coupled to the fourth test point 420D.

[0058] The splitter 470 in the PDCR 400 is a 2x2 splitter, rather than the 1x2 splitter 140 in the PDCR 100. Therefore, the other input port of the splitter 470 is coupled to the fifth test point 420E.

[0059] Each of the first to fifth test points 420F can be a surface grating coupler, a surface of an optical waveguide for butt coupling with an optical fiber, or a photonic wire bonding interface, such as the interface described in PCT / CA2022 / 051004 "Detection and testing of photonic devices based on printed photonic components."

[0060] In another embodiment of the present invention, the respective first and second input ports 430A and 430B of the first optical hybrid 410A and / or the respective first and second input ports 450A and 450B of the second optical hybrid 410B may be reversely configured such that the first input port 430A of the first optical hybrid 410A and the first input port 450A of the second optical hybrid 410B are coupled to the laser 120 via the splitter 470, while the second input port 430B of the first optical hybrid 410A and the second input port 450B of the optical hybrid 410B are coupled to the first test point 420A and the third test point 420C, respectively.

[0061] refer to Figure 5 , shows a photonic mixing circuit (optical mixer 500) for a coherent receiver according to an embodiment of the present invention. Therefore, the optical mixer 500 is respectively based on the local oscillator and the signal input E LO and E S , four output signals E1, E2, E3, E4 are generated accordingly. The transfer matrix of the optical mixer 500 is E1 and E1 and is given by the following equations (1) to (3).

[0062] refer to Figure 6 , shows a photonic hybrid circuit (optical hybrid 600) for a coherent receiver according to an embodiment of the present invention. Therefore, the optical hybrid 600 generates a signal according to the local oscillator and the signal input E LO and E S, four output signals E1, E2, E3, E4 are generated accordingly. The transfer matrix of the optical mixer 600 is E1 and E1 and is given by the following equations (4) to (6).

[0063] In addition to addressing improvements within photonic coherent receivers, the inventors have identified improved designs for modulators to address the speed matching between the modulated electrical and optical signals. In a traveling wave (TW) MZI modulator, there are two competing trade-offs, reduced drive achieved by increasing device length and increased modulation bandwidth as the device length is reduced. By improving the speed matching between the traveling wave electrical signal and the propagating optical signal, the bandwidth can be increased for a given length, allowing the voltage to be reduced for a given bandwidth. In silicon photonics, the effective refractive index of the TW electrode is higher than that of the optical waveguide, allowing the optical signal to propagate faster.

[0064] Therefore, if Figure 7 As shown, the inventors have established a periodic structure to provide periodic adjustment to match the phases of the optical and electrical signals. Figure 7 As shown in the schematic diagram 700 in FIG. 1 , a coplanar waveguide TW electrode is shown to include internal signal lines 720 and 730 and external ground lines 710 and 740. Periodically arranged along the structure are contacts 760(1) to 760(N), which are arranged and electrically connected to the signal lines 720 and 730. In order to slow down the optical signal, a pair of optical waveguides 770 adopts a periodic sinusoidal geometry so that the optical path length between each pair of adjacent contacts 760(1) to 760(N) is longer than the physical distance between them, thereby providing improved phase matching, thereby increasing the modulation bandwidth of the modulator using the TW electrode.

[0065] The spacing D between each pair of contacts 760(1) to 760(N) is established based on one or more factors selected from the group consisting of: speed mismatch between electrical and optical signals, speed of optical signals, speed of electrical signals, target bandwidth of the modulator, and length of the modulator including the first contacts 760(1) to 760(N). The second contact 780 provides another contact point so that current flows from the first contacts 760(1) to 760(N) to the second contact 780, thereby adjusting its refractive index.

[0066] Obviously, different driving schemes and material properties can be employed to tune the refractive index via multiple contacts arranged along the length of the TW electrode.

[0067] The length L of each of the first contacts 760(1) to 760(N) is established based on one or more factors selected from the group consisting of: a speed mismatch between the electrical and optical signals, a speed of the optical signal, a speed of the electrical signal, a target bandwidth of the modulator, and a length of the modulator including the first contacts 760(1) to 760(N). In an embodiment of the present invention, the length L may be constant for all of the first contacts 760(1) to 760(N), or it may vary such that the length of the contacts within the first contacts 760(1) to 760(N) is adjusted based on a defined mathematical function that is established based on one or more factors selected from the group consisting of a speed mismatch between the electrical and optical signals, a speed of the optical signal, a speed of the electrical signal, a target bandwidth of the modulator, a length of the modulator including the first contacts 760(1) to 760(N), and an attenuation of the TW electrode.

[0068] like Figure 7 The optical waveguide shown in FIG. has a light source from an input splitter (at Figure 7 is shown as a Y-junction) to the output splitter (in Figure 7 760(1) to 760(N)).

[0069] like Figure 7 The optical waveguide shown in FIG. has a light source from an input splitter (at Figure 7 is shown as a Y-junction) to the output splitter (in Figure 7 In other embodiments of the present invention, the periodic offset may be defined by another mathematical function.

[0070] It will be apparent to those skilled in the art that the phase matching scheme can be applied to phase modulators as well as amplitude modulators, or to other amplitude modulator geometries.

[0071] Specific details are given in the above description to provide a thorough understanding of the embodiments. However, it should be understood that the embodiments can be practiced without these specific details. For example, circuits can be shown in block diagram form to avoid unnecessary details to obscure the embodiments. In other cases, well-known circuits, processes, algorithms, structures and techniques can be shown without unnecessary details to avoid obscuring the embodiments.

[0072] The foregoing disclosure of exemplary embodiments of the present invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Many variations and modifications of the embodiments described herein will be apparent to those of ordinary skill in the art in light of the foregoing disclosure. The scope of the present invention is limited only by the appended claims and their equivalents.

[0073] In addition, when describing representative embodiments of the present invention, the specification may have presented the method and / or process of the present invention as a specific sequence of steps. However, insofar as the method or process does not rely on the specific order of the steps set forth herein, the method or process should not be limited to the specific order of the steps described. As will be appreciated by those of ordinary skill in the art, other sequences of steps are also possible. Therefore, the specific sequence of the steps set forth in the specification should not be interpreted as a limitation to the claims. In addition, the claims relating to the method and / or process of the present invention should not be limited to the steps of performing them in written order, and those skilled in the art can easily understand that the order can be changed and still remain within the spirit and scope of the present invention.

Claims

1. A photonic circuit, comprising: an adiabatic coupler having a pair of input ports and a pair of output ports; a first coupler having an input port coupled to an output port of the pair of output ports of the adiabatic coupler; a second coupler having an input port coupled to the other of the pair of output ports of the adiabatic coupler; as well as A third coupler, the third coupler having a pair of input ports and a pair of output ports; wherein, An output port of the pair of output ports of the third coupler is coupled to the other input port of the first coupler; The other output port of the pair of output ports of the third coupler is coupled to the other input port of the second coupler; A pair of output ports of the first coupler are coupled to a first balanced photodetector; and A pair of output ports of the second coupler are coupled to a second balanced photodetector.

2. The photonic circuit according to claim 1, further comprising At least one of: a photonic test point coupled to the other input port of the adiabatic coupler for coupling a test optical signal to the photonic circuit; and Another photon test point, coupled to the another input port of the third coupler, is used to couple other test optical signals to the photon circuit.

3. A method for receiving photon data, comprising: A photonic circuit is provided comprising a pair of photonic hybrid circuits, each of the photonic hybrid circuits comprising: an adiabatic coupler having a pair of input ports and a pair of output ports; a first coupler having an input port coupled to an output port of the pair of output ports of the adiabatic coupler; a second coupler having an input port coupled to the other of the pair of output ports of the adiabatic coupler; and A third coupler, the third coupler having a pair of input ports and a pair of output ports; wherein, An output port of the pair of output ports of the third coupler is coupled to the other input port of the first coupler; The other output port of the pair of output ports of the third coupler is coupled to the other input port of the second coupler; A pair of output ports of the first coupler are coupled to a first balanced photodetector; and A pair of output ports of the second coupler are coupled to a second balanced photodetector; providing a splitter coupled to a laser emitting at a predetermined wavelength having a predetermined polarization, wherein a first output of the splitter is coupled to an input port of the pair of input ports of the adiabatic coupler within a photonic hybrid circuit of the pair of photonic hybrid circuits, and a second output of the splitter is coupled to an input port of the pair of input ports of the adiabatic coupler within the other photonic hybrid circuit of the pair of photonic hybrid circuits; A polarization splitter and rotator (PSR) circuit is provided coupled to a network for receiving an optical signal of a predetermined wavelength, wherein a first output of the PSR circuit is split from an optical signal received by the PSR circuit having a predetermined polarization, and the first output of the PSR circuit is coupled to an input port of the third coupler of a photonic hybrid circuit in the pair of photonic hybrid circuits, and a second output of the PSR circuit is split from a received optical signal having a polarization orthogonal to the predetermined polarization and is rotated to the predetermined polarization before becoming the second output of the PSR circuit, and the second output of the PSR circuit is coupled to an input port of the third coupler in the other photonic hybrid circuit in the pair of photonic hybrid circuits.

4. The method according to claim 3, wherein: At least one of the pair of photonic hybrid circuits comprises at least one of: a photonic test point coupled to the other input port of the adiabatic coupler for coupling a test optical signal to the photonic hybrid circuit; and Another photon test point, coupled to the another input port of the third coupler, is used to couple other test optical signals to the photon hybrid circuit.

5. A photonic circuit comprising: an adiabatic coupler having a pair of input ports and a pair of output ports; a first coupler having an input port coupled to an output port of the pair of output ports of the adiabatic coupler; a second coupler having an input port coupled to the other of the pair of output ports of the adiabatic coupler; as well as A third coupler, the third coupler having a pair of input ports and a pair of output ports; wherein, An output port of the pair of output ports of the third coupler is coupled to the other input port of the first coupler; and The other output port of the pair of output ports of the third coupler is coupled to the other input port of the second coupler.

6. The photonic circuit according to claim 5, further comprising a first balanced photodetector coupled to a pair of output ports of the first coupler; and A second balanced photodetector is coupled to a pair of output ports of the second coupler.

7. The photonic circuit according to claim 5, further comprising At least one of: a photonic test point coupled to the other input port of the adiabatic coupler for coupling a test optical signal to the photonic circuit; and Another photon test point, coupled to the another input port of the third coupler, is used to couple other test optical signals to the photon circuit.

8. A device comprising: Optical waveguides; A traveling wave electrode, the traveling wave electrode is used to cause a phase shift of an optical signal propagating in the optical waveguide, the traveling wave electrode comprising a plurality of contacts arranged along a section of the optical waveguide; wherein, The optical waveguide has a periodic offset along the length of the segment of the optical waveguide from an overall path of the optical waveguide by a mathematical function, the overall path being defined by another mathematical function over the length of the segment of the optical waveguide; and The period of the periodic shift is defined according to a spacing between adjacent pairs of contacts of the plurality of contacts.

9. The device according to claim 8, wherein: The spacing between each pair of contacts in the plurality of contacts is established based on one or more factors selected from the group consisting of: a speed mismatch between the electrical signal and the optical signal, a speed of the optical signal, a speed of the electrical signal, a target bandwidth of the modulator, and a length of the plurality of contacts.

10. The device according to claim 8, wherein: The length of each pair of contacts in the plurality of contacts is established based on one or more factors selected from the group consisting of: a speed mismatch between the electrical signal and the optical signal, a speed of the optical signal, a speed of the electrical signal, a target bandwidth of the modulator, and the lengths of the plurality of contacts.

11. The device according to claim 8, wherein: The nominal length of each of the plurality of contacts is established based on one or more factors selected from the group consisting of: a speed mismatch between the electrical signal and the optical signal, a speed of the optical signal, a speed of the electrical signal, a target bandwidth of the modulator, and a length of the plurality of contacts; as well as The length of each of the plurality of contacts is adjusted according to another mathematical function established based on one or more factors selected from the group consisting of: the velocity mismatch of the electrical and optical signals, the velocity of the optical signal, the velocity of the electrical signal, the target bandwidth of the modulator, the length of the modulator including the plurality of contacts, and the attenuation of the TW electrode.

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