Silicon optical phase modulators and their applications

Abstract

The optoelectronic device (100) includes a substrate (107), an optical waveguide (108) disposed on the substrate, a dielectric layer (106) disposed across the optical waveguide on the substrate, and a film (112) comprising an electro-optic material disposed across the dielectric layer and covering at least a portion of the optical waveguide. Electrodes (114, 116) are configured to apply an electric field to the electro-optic material near the optical waveguide, thereby modulating the phase of the guided light wave propagating through the waveguide.

Description

[Technical Field]

[0001] This invention generally relates to optoelectronic systems, and more particularly to optoelectronic phase modulators and their applications. [Background technology]

[0002] Silicon optical communication systems use silicon and its compounds as the optical medium. The optical medium is patterned with submicron precision within optical waveguides and other minute optical communication components such as amplitude and phase modulators of the optical radiation propagating within the waveguides. [Overview of the project] [Problems that the invention aims to solve]

[0003] The embodiments of the present invention described below provide improved design and fabrication methods for silicon optical communication modulators and their applications. [Means for solving the problem]

[0004] Accordingly, embodiments of the present invention provide an optoelectronic device comprising a substrate, an optical waveguide disposed on the substrate, a dielectric layer disposed across the optical waveguide on the substrate, and a film comprising an electro-optic material disposed across the dielectric layer and covering at least a portion of the optical waveguide. The device further includes electrodes configured to apply an electric field to the electro-optic material near the optical waveguide, thereby modulating the phase of a guide light wave propagating through the waveguide.

[0005] In the disclosed embodiment, a controller is coupled to apply a voltage between electrodes to generate an electric field.

[0006] In another embodiment, the optical waveguide comprises an optical material having a first intrinsic refractive index, while the electro-optical material has a second intrinsic refractive index greater than the first refractive index. Furthermore, the waveguide has a first effective refractive index, the film has a second effective refractive index, and the optical waveguide, dielectric layer, and film have dimensions selected such that the first effective refractive index is greater than the second effective refractive index at the wavelength of the guide light wave. In addition to or instead of this, the guide light wave has a wavelength within the visible range of the spectrum.

[0007] In yet another embodiment, the electro-optic material includes barium titanate (BTO). In addition to or instead of this, the waveguide includes silicon nitride (SiN), and the dielectric material includes silicon dioxide (SiO2). In addition to or instead of this, the substrate is selected from a set of substrate materials consisting of silicon and fused silica.

[0008] In one embodiment, the dielectric layer has a thickness between 50 nm and 500 nm.

[0009] In the disclosed embodiments, the film covers a first portion of the optical waveguide but not a second portion of the optical waveguide, and the optical waveguide includes a coupler comprising a pair of opposing tip sections that meet at the boundary of the film between the first and second portions.

[0010] Furthermore, an embodiment of the present invention provides an optoelectronic device including a substrate and a Mach-Zehnder interferometer disposed on the substrate. The Mach-Zehnder interferometer includes first and second optical waveguides, a splitter coupled to receive an input guiding optical wave and split the guiding optical wave into first and second guiding optical waves that propagate in the first and second optical waveguides respectively, and a combiner coupled to receive the first and second guiding optical waves emitted from the first and second optical waveguides such that the first and second guiding optical waves interfere to form an output guiding optical wave. The device includes a dielectric layer disposed across the first and second optical waveguides on the substrate, an electro-optic material disposed across the dielectric layer, a film covering at least one of the first and second optical waveguides, and an electrode configured to apply an electric field to the electro-optic material near at least one of the first and second optical waveguides, thereby modulating the intensity of the output guiding optical wave by changing the phase difference between the first and second guiding optical waves.

[0011] In yet another embodiment, the film covers both the first and second optical waveguides. In addition or alternatively, the electrode includes a first pair of electrodes proximate to the first optical waveguide and a second pair of electrodes proximate to the second optical waveguide.

[0012] Furthermore, embodiments of the present invention provide an optoelectronic device including a substrate and a network of interconnected Mach-Zehnder interferometers disposed on the substrate. Each Mach-Zehnder interferometer includes a first and a second optical waveguide, a splitter coupled to receive an input guiding optical wave and split the guiding optical wave into first and second guiding optical waves that propagate into the first and second optical waveguides, respectively, and a combiner coupled to receive the first and second guiding optical waves emitted from the first and second optical waveguides such that the first and second guiding optical waves interfere to form an output guiding optical wave. The device further includes a dielectric layer disposed across a plurality of interconnected Mach-Zehnder interferometers on the substrate, a film covering at least a portion of the network of interconnected Mach-Zehnder interferometers including an adjacent layer of an electro-optic material disposed across the dielectric layer, an electrode configured to apply an electric field to the electro-optic material near at least one of the first and second optical waveguides in each of at least a portion of the Mach-Zehnder interferometers, and a controller coupled to apply a voltage between the electrodes to switch a guiding optical wave passing through the network.

[0013] In the disclosed embodiment, the film covers a first portion of the network but not a second portion of the network, and at least one of the optical waveguides includes a coupler including a pair of opposing tapered portions that meet at the boundary of the film between the first and second portions. In addition or alternatively, at least a portion of the Mach-Zehnder interferometers are entirely confined below the film and do not include opposing tapered portions.

[0014] The present invention will be more fully understood from the following detailed description of its embodiments in conjunction with the drawings.

Brief Description of the Drawings

[0015] [Figure 1] It is a schematic cross-sectional view of an electro-optic device according to an embodiment of the present invention. [Figure 2] It is a diagram of a plot showing the effective refractive index of a guided wave as a function of the width of an electro-optic film and a waveguide in the device of FIG. 1 according to an embodiment of the present invention. [Figure 3] This figure shows a plot of the effective refractive index of the guide wave as a function of the width of the electro-optic film and waveguide in the device of Figure 1 according to an embodiment of the present invention. [Figure 4] This is a schematic top view illustrating the transition of a waveguide into a phase modulator according to an embodiment of the present invention. [Figure 5] This is a schematic top view of a Mach-Zehnder interferometer according to an embodiment of the present invention. [Figure 6] This is a schematic top view of a network of a nested Mach-Zehnder interferometer according to an embodiment of the present invention. [Modes for carrying out the invention]

[0016] Introduction Silicon optical communication systems utilize waveguide-based interferometers, such as Mach-Zehnder interferometers, as optical modulation and switching circuits. Generally, a phase modulator is used to modulate the phase of the guide wave in at least one of the interferometer's arms. Modulation of the relative optical phase between the two arms of the interferometer causes the guide wave, after passing through the two arms, to interfere in either a constructive or destructive manner, thereby modulating the interferometer's output power. For this purpose, silicon optical communication phase shift modulators may be implemented using various techniques such as thermal phase shifters, PIN diodes, stress optical actuators, or Pockels modulators (Pockels cells). (In this specification, the term “silicon optical communication phase modulator” is used to refer to optical phase modulators equivalent to silicon optical communication systems and their fabrication processes, although the components of the phase modulator may include materials other than silicon.)

[0017] There is considerable interest in integrating silicon optical phase modulators into optical logic networks using existing silicon optical fabrication processes, particularly for applications like quantum computing. This type of integration can be challenging in quantum computing systems using visible light, such as those based on diamond color centers. Such networks typically have the following requirements for modulators: • Transmittance at visible wavelengths, • Integration with low-loss, low-luminescence silicon nitride (SiN) waveguides. • Ultra-low power dissipation during cryogenic operation. • Operation as both a high-speed modulator in the gigahertz bandwidth range and a low-speed phase shifter in the megahertz speed range, and • Loss independent of phase.

[0018] In addition, it is desirable that the network be equivalent to a common semiconductor manufacturing process, such as a complementary metal-oxide-semiconductor (CMOS) process, through its built-in optical detection capabilities and adaptability to complex routing.

[0019] To satisfy the requirements described above, embodiments of the present invention described herein use a Pockels modulator based on barium titanate (BaTiO3, also abbreviated as BTO). Conventionally, BTO-based silicon optical phase modulators operate in the near-infrared (NIR) wavelength, where both BTO and Si are transparent. In the visible wavelength, BTO remains transparent, but Si absorbs optical radiation and cannot be used in this spectral range. Furthermore, simply using an NIR single-mode BTO waveguide structure in the visible range would result in the BTO structure acting as a multimode waveguide.

[0020] To overcome this limitation, embodiments of the present invention described herein use a BTO film that forms a waveguide coating on a SiN waveguide. The BTO film is isolated from the SiN waveguide by a subwavelength gap containing a dielectric material such as SiO2. A controller is coupled to the BTO film through conductive electrodes. A guide wave having wavelengths in the visible portion of the spectrum propagates through the SiN waveguide, with only the evanescent portion of the propagation mode overlapping the BTO film. The BTO film modifies the effective refractive index of the propagating guide wave as a function of the voltage applied between the electrodes. The change in voltage alters the phase of the propagation mode, thus imparting low-loss phase modulation to the visible wavelength guide wave. While the inventors have found BTO advantageous for this purpose, alternative embodiments may use other electro-optic materials to form the film of the optical phase modulator.

[0021] In one embodiment, a guided Mach-Zehnder interferometer based on a SiN waveguide has a BTO film covering one or both of its arms. By applying an electric field across the BTO film adjacent to one of the interferometer's arms, the phase of the guide wave propagating within that arm is modulated, and therefore the output of the interferometer is modulated due to interference between the guide waves from the two arms.

[0022] In another embodiment, multiple guided Mach-Zehnder interferometers are interconnected in a network. The entire network is covered with a BTO film. By applying an electric field across the BTO film adjacent to the interferometer's selection arm, the outputs of these interferometers can be modulated, thereby switching the network logic configuration.

[0023] Embodiments of the disclosure of the present invention provide a photoelectronic device including a phase modulator comprising an optical waveguide and a layer covering an electro-optic material. A controller is coupled to electrodes on the electro-optic material layer and applies an electric field between the electrodes such that it modulates the optical phase of a guide wave of optical radiation propagating through the optical waveguide.

[0024] An additional embodiment provides a Mach-Zehnder interferometer comprising two arms, each containing an optical waveguide. At least one of the two arms is covered with an electro-optic material layer. A controller is coupled to electrodes on the electro-optic material layer and modulates the refractive force emitted from the interferometer by applying an electric field between the electrodes such that it modulates the optical phase of the guide wave of the optical radiation propagating within the arm.

[0025] Yet another embodiment provides a guided interferometer network comprising multiple interconnected guided Mach-Zehnder interferometers and adjacent layers of electro-optic material covering them. Controllers are coupled to electrodes on the electro-optic material. The controllers modulate the refractive force emitted from the selective interferometer by applying an electric field between adjacent selective electrodes on the arms of the selective interferometer.

[0026] Phase modulator Figure 1 is a schematic cross-sectional view of an optoelectronic device 100 according to an embodiment of the present invention. The device 100 includes a silicon optical communication phase modulator 102 and a controller 104. The phase modulator 102 includes a silicon dioxide (SiO2) layer 106 deposited on a substrate 107, such as a silicon on an insulator (SOI) substrate. In alternative embodiments, the substrate 107 may include silicon containing SiO2 or silicon with an SiO2 layer grown on top. A width W is present across one of the SiO2 layers 106. WG and thickness Th WG A single-mode SiN waveguide 108 having the above characteristics is deposited and then covered with yet another thin layer of SiO2. Referring to the Cartesian coordinate system 110, the guided optical radiation propagates in the z direction within the waveguide 108.

[0027] A thin sheet of BTO, called a BTO film 112, is deposited over the thin portion of the SiO2 layer 106 covering the waveguide 108, so as to be parallel to the waveguide 108 and sufficiently close to it. This is so that the evanescent portion (also called the mode "tail") of the single-mode guided wave propagating within the waveguide overlaps with the film. Therefore, the BTO film 112 acts as a coating for the waveguide 108. The dimensions of the BTO film 112 in the x and y directions are the width W, respectively. BTOand thickness Th BTO Labeled as G. The gap formed between the BTO film 112 and the waveguide 108 by the SiO2 layer is G BTO / WG It is labeled as follows. Conductive electrodes 114 and 116 bond the BTO film 112 to the controller 104, and the gap between these electrodes is G COND Labeled as such. Exemplary numerical values ​​for the above dimensions are provided below. In the z direction, the length of the phase modulator 102 is selected such that a desirable phase shift range is obtained in the guide wave propagating through the waveguide 108 as a function of the voltage applied between electrodes 114 and 116.

[0028] The controller 104 typically includes a programmable processor programmed by software and / or firmware to drive the phase modulator 102 by applying a voltage across the film through electrodes 114 and 116. Alternatively, or in addition to this, the controller 104 includes a connection logic circuit and / or a programmable hardware logic circuit to drive the phase modulator 102. Although the controller 104 is shown as a single monolithic functional block for simplification purposes in the figure, in practice, the controller may include a single chip or a set of two or more chips with a suitable interface for outputting drive signals. Alternatively, the controller 104 may be fabricated as an integrated circuit on a substrate 107.

[0029] When the controller 104 applies a voltage across the BTO film 112, the refractive index of the film changes due to the electro-optic effect in response to the electric field generated within the film. This change in the local refractive index of the BTO film 112 affects the effective refractive index n of the guide mode propagating through the waveguide 108. eff Change n. eff This change alters the phase of the guidance mode and therefore contributes to the phase modulation function of device 100.

[0030] This embodiment has several advantages over other types of modulators, including the following: a. Due to the small overlap between the BTO film 112 and the modes propagating in the waveguide 108, the thickness variations of the film and the waveguide have only a minor impact on the propagation loss. b. Since the BTO film 112 does not guide the propagation mode, there is no need to etch the film to accept the mode, and thus the potential adverse effects due to the sidewall roughness associated with the etching process are avoided. c. Since the guiding mode propagates only within the waveguide 108, there is no transition of the guiding mode between the SiN waveguide and the electro-optic medium (such as BTO), and thus the power loss associated with such a transition is avoided. d. When coupling the guided wave between the waveguide and the conventional modulator, the alignment in the xy plane between the BTO film 112 and the waveguide 108 can be relaxed to up to several hundred nanometers instead of being required within several tens of nanometers. However, in order to avoid the overlap between the waveguide 108 and the electrodes 114 and 116, it is desirable that the distance between the sidewall of the waveguide 108 and the closest edge of either the electrode 114 or 116 is at least 2 μm. e. The SiN material of the waveguide 108 can be deposited using a high-temperature process such as low-pressure chemical vapor deposition (LPCVD), which is beneficial for reducing optical losses.

[0031] The process constraints and considerations of the guiding mode require that the BTO film 112 has a minimum width W of around 10 μm, which is substantially larger than the waveguide width W. WG Such a wide BTO film will potentially have many guided wave modes (cladding modes) in both the x and y directions. Furthermore, since BTO has a higher refractive index (n = 2.4025) than that of SiN (n ≈ 2.0), the BTO mode volume becomes even larger. As will be described in more detail below, in order to minimize the coupling between the guiding mode of the BTO film 112 and the guiding mode of the waveguide 108, the phase modulator 102 is configured such that the effective refractive index n of the fundamental mode of the waveguide BTO is greater than the effective refractive index n of the fundamental mode of the film. eff0,WG eff0,BTO

[0032] Figures 2 and 3 show plots 302 and 304 according to embodiments of the present invention, illustrating the effective refractive index of the coating mode (plot 302) and the guided wave mode (plot 304) as functions of the widths of the BTO film 112 and waveguide 108, respectively. The effective refractive index was calculated at a wavelength of 637 nm.

[0033] In plot 302, curves 306 and 308 show the effective refractive index for the lowest coverage modes 0 (TE) and 1 (TM) at a film thickness of 50 nm Th, respectively. BTO Width W of BTO film 112 BTO This is shown as an example of a function of the effective refractive index n of the basic coating mode of the BTO film 112. eff0,BTO This is more relevant by preventing coupling between the membrane and the waveguide 108. eff0,BTO The value of is W BTO = 1.659 at 5μm = W BTO It increases to 1.660 at 20 μm.

[0034] In plot 304, curves 310, 312, 314, and 316 represent the effective refractive indices of waveguide modes 0 (TE), 1 (TM), 2 (TE), and 3 (TM), respectively. BTO A waveguide thickness of Th that is effectively larger than 300 nm WG The width W of waveguide 108 WG This is shown as an example of a function of the effective refractive index n for the fundamental TE mode (mode 0) of waveguide 108. eff0,WG This is most relevant in preventing coupling between the waveguide and the film 112. n regarding the basic TE mode eff0,WG The value of is W WG = 1.53 from W at 150 nm WG = Increases to 1.73 at 330nm. (In fact, to accept a 20nm safety tolerance in the lithography process, a nominal n of 1.717 is used with a nominal width of 310nm.) eff0,WG This is the result. ) For reference, the refractive index of SiO2 is shown in curve 318.

[0035] Both parameters W WG and Th WGThe following are important for the design of waveguide 108: ·Width W WG This must be maximized to reduce scattering losses from the etched sidewalls. Thickness WG This must be maximized to reduce the sensitivity to thickness changes related to the growth of the SiN layer.

[0036] These two conditions are not independent for single-mode waveguides, and the waveguide width W WG The increase in the maximum allowable thickness Th WG It reduces, and vice versa.

[0037] 310nm nominal width W WG and a thickness of 300nm Th WG For a waveguide 108 having n eff0,WG >n eff0,BTO The above requirements are fully satisfied, and therefore the coupling between the waveguide 108 and the BTO film 112 is minimized.

[0038] In one embodiment, the gap G between the waveguide 108 and the BTO film 112 BTO / WG This is 150 nm. Alternatively, this gap can have different widths, for example, between 50 nm and 500 nm. A drive voltage of 20 V is applied by the controller 104, and the electrode gap G COND G BTO / WG When = 150 nm, the z-length of the phase modulator 102, 102 μm, is sufficient for a 180-degree phase shift with respect to the guide wave. (A 180-degree phase shift results in destructive interference, i.e., zero output power, at the exit of the interferometer.) When the phase modulator 102 is used in both arms of the Mach-Zehnder interferometer, the length of each modulator can be divided in half to 61 μm. The coupling loss at each end of the phase modulator 102 is calculated to be 0.926%. The effect on mode loss is simply 2.914 * 10 -10 Since it is dB, the above 6 μm gap G COND This was selected.

[0039] Waveguide transition Figure 4 is a schematic top view 400 showing the transition from waveguide 402 to phase modulator 404 according to an embodiment of the present invention.

[0040] Waveguide 402 is similar to waveguide 108 in Figure 1. Phase modulator 404, partially shown within the dotted frame 406, is similar to phase modulator 102 in Figure 1. The orientation of phase modulator 404 is shown in appropriately rotated Cartesian coordinates 110. Phase modulator 404, like phase modulator 102, includes a BTO film 408 and electrodes 410 and 412. SiN waveguide 402 is embedded within SiO2 layer 414.

[0041] Within section 416 of waveguide 402, which is well outside the phase modulator 404, and within section 418, which is well inside the phase modulator, waveguide 402 is a single-mode SiN waveguide. In this embodiment, these sections of waveguide 402 have a width of 310 nm W WG and a thickness of 330nm Th WG Although it has the above dimensions, larger or smaller dimensions can be used instead. When the waveguide 402 is introduced into the phase modulator 404 without any change in its dimensions, the guide wave propagating in the waveguide is considered to undergo the sum of the incident coupling loss and the exit coupling loss of the -0.67 propagation mode when it is incident into the phase modulator and when it is exited therefrom.

[0042] To reduce this coupling loss, the cross-sectional dimensions of waveguide 402 are modified to form a coupler that includes a pair of opposing tip sections that meet at the boundary of phase modulator 404 shown in frame 406, within sections 420 and 422. Within section 420, width W WG It increases linearly from 310 nm to 1000 nm. Within section 422, the tip is reversed, and the width W WGThe signal is reduced linearly from 1000 nm to 310 nm. When the length of each tipping, i.e., the length of each section 420 and 422, is set to 10 μm, the guided wave undergoes adiabatic transition to the new dimensions, and the total coupling loss is reduced to -0.12 dB during incidence into and exit from the phase modulator 404 (compared to a loss of -0.69 dB for the waveguide without tipping). Alternatively, waveguide 402, and the tipping within sections 420 and 422, may have other longitudinal and transverse dimensions depending on the application requirements.

[0043] Mach-Zehnder interferometer Figure 5 is a schematic top view of a Mach-Zehnder interferometer 500 according to an embodiment of the present invention.

[0044] Interferometer 500 is based on a single-mode SiN waveguide 502 within an SiO2 layer, similar to waveguides 102 and 402 (Figures 1 and 4, respectively). Interferometer 500 includes two arms 504 and 506. (The term "arm" is used to refer to one of the waveguides that sets the path for the guided wave through the interferometer.) Directional waveguide couplers 508 and 510 contribute as 50:50 guided wave splitter / coupler at the respective inlet and outlet of interferometer 500. (Directional couplers are used instead of multimode splitters to prevent parasitic back reflections.) Directional waveguide coupler 508 contributes as a splitter that receives the input guided light wave and splits it into a guided light wave that propagates through arm 504 and a guided light wave that propagates through arm 506. The directional waveguide coupler 510 acts as a combiner, receiving a first guide light wave emitted from arm 504 and a second guide light wave emitted from arm 506, and coupling these waves so that they interfere with each other to form an output guide light wave.

[0045] Two phase modulators 512 and 514 (similar to phase modulator 102 in Figure 1), each containing BTO films 516 and 518 and electrodes 520, 522, 524, and 526, are arranged across arms 504 and 506, respectively. In this example, the width W of the BTO films 516 and 518 is also shown. BTOThe thickness is 25 μm and 50 nm. The gap G between arms 504 and 506 and BTO films 516 and 518 respectively. BTO / WG The wavelength is 150 nm. Other dimensions can be used instead. Furthermore, in some applications, the BTO film only needs to cover one of the arms.

[0046] Arms 504 and 506 enter and exit their respective phase modulators 512 and 514 through tapered transitions of the type shown in Figure 4. A controller 528, similar to controller 104 (Figure 1), is coupled to electrodes 520-526 to drive phase modulators 512 and 514. By adjusting the voltage applied to the electrodes, controller 528 can change the relative phase of the light waves guided within arms 504 and 506, thereby switching the intensity of the output from interferometer 500 through constructive or destructive interference between these waves.

[0047] In this example, the z-length of the interferometer 500 is 280 μm, and the x-width is 85 μm. The gap in the directional couplers 508 and 510 (i.e., the separation of the two waveguides forming the coupler) is 200 nm, requiring a length of 15 μm for each coupler. In alternative embodiments, Mach-Zehnder interferometers of various dimensions can be used.

[0048] Given the exemplary dimensions described above, the total insertion loss of the interferometer 500 is estimated to be simply about 0.16 dB.

[0049] Figure 6 is a schematic top view of the network 600 of a nested Mach-Zehnder interferometer 602 according to an embodiment of the present invention. For the sake of simplification, a controller similar to the controller 528 (Figure 5) that drives the phase modulator is omitted from this figure. The controller applies a voltage between at least some of the electrodes of the interferometer 602 to switch the guide light waves passing through the network 600.

[0050] The interferometers 602 within the network 600 are similar to or identical to interferometer 500 (Figure 5) and are coupled to each other through an inlet and an outlet. Adjacent BTO films 604 cover the network 600, and each arm of each interferometer 602 has its own electrode pair 606, thereby forming a phase modulator for each arm (similar to phase modulators 512 and 514 in Figure 5). Due to the typical lateral separation of 100 microns or more between adjacent interferometers 602, crosstalk between the phase modulators of these interferometers can be ignored.

[0051] Waveguide 608, similar to waveguide 502 in Figure 5, is coupled to enter and exit the network 600 using tapered couplers, as shown in Figure 4. The tapered input and output couplers are shown in insets 610 and 612, respectively. Since adjacent identical BTO films 604 cover all interferometers 602 in the network 600, tapered input and output couplers are required only at the network's input and output ports, rather than at the input and output ports of each interferometer, as in conventional embodiments. Thus, the use of adjacent BTO films substantially reduces losses at the transitions between elements of the network 600.

[0052] Figure 6 simply shows four interferometers 602 for illustrative purposes. In alternative embodiments, more (or fewer) interferometers 602 may be used. The loss of a Mach-Zehnder interferometer 602 at the edge of network 600 having a tapered transition at either its input or output is estimated to be 0.1782 dB, compared to an interferometer inside the network (without a tapered transition) at an estimated 0.1272 dB.

[0053] That is, for example, a network of 10 Mach-Zehnder interferometers, each having one input interferometer and one output interferometer, would have a total loss of approximately 1.374 dB. By similar calculations, a network of 20 interferometers would have a total loss of approximately 2.646 dB, and a network of 30 interferometers would have a total loss of approximately 3.918 dB. In contrast, in the absence of the tapered transition of the type described above, similar networks of 10, 20, and 30 Mach-Zehnder interferometers would suffer total losses of 7.62 dB, 15.24 dB, and 22.86 dB, respectively.

[0054] In addition to the benefit of reducing losses, the use of adjacent BTO films such as film 604 has the advantage of reducing the chip area of ​​the network, simplifying BTO etch patterning, and thereby lowering process costs.

[0055] Alternative Embodiments In alternative embodiments, the network of a Mach-Zehnder interferometer, such as network 600, can be manufactured on a SiN-only platform using fused silica wafers or silicon wafers with oxide layers grown on silicon, rather than SOI. In such cases, advantageous features of SOI, such as the built-in detector, may be lost. However, BTO films are thought to be able to be grown at higher temperatures (without being limited by the constraints of the back-end (BEOL) process of the line), and therefore are thought to have improved optical properties. In addition, processing BTO films at the front-end (FEOL) of the line allows for the use of better lithography processes.

[0056] In the embodiments described above, certain specific dimensions were cited, but these dimensions were presented solely for the purpose of illustrating certain principles of the present invention. Those skilled in the art will recognize alternative dimensions for implementing these principles after reading the disclosure of the present invention, and these dimensions are considered to be within the scope of the invention. Therefore, it will be acknowledged that the embodiments described above are illustrative and that the present invention is not limited to those specifically shown and described above. Rather, the scope of the present invention includes combinations and partial combinations of the various features described above, as well as both variations and modifications thereof that are expected to be conceived by those skilled in the art after reading the above description and that are not disclosed in the prior art. [Explanation of symbols]

[0057] 100 Optoelectronic Devices 102 Phase Modulator 106 Dielectric layer 108 Waveguides 112 Membrane 114, 116 electrode

Claims

1. circuit board and An optical waveguide arranged on the substrate, A dielectric layer arranged across the optical waveguide on the substrate, A film comprising an electro-optic material arranged across the dielectric layer and covering at least a portion of the optical waveguide, An electrode configured to apply an electric field to the electro-optic material near the optical waveguide, thereby modulating the phase of the guide light wave propagating within the waveguide, Optoelectronic devices including optoelectronic devices.

2. The device according to claim 1, comprising a controller coupled to apply a voltage between the electrodes in order to generate the electric field.

3. The optical waveguide includes an optical material having a first intrinsic refractive index, while the electro-optic material has a second intrinsic refractive index greater than the first refractive index. The waveguide has a first effective refractive index, the film has a second effective refractive index, and the optical waveguide, the dielectric layer, and the film have dimensions selected such that the first effective refractive index is greater than the second effective refractive index at the wavelength of the guide light wave. The device according to claim 1.

4. The device according to claim 3, wherein the guiding light wave has a wavelength within the visible range of the spectrum.

5. The device according to any one of claims 1 to 4, wherein the electro-optic material comprises barium titanate (BTO).

6. The waveguide contains silicon nitride (SiN), and the dielectric material is silicon dioxide (SiO2). 2 The device according to claim 5, which includes ).

7. The device according to claim 6, wherein the substrate is selected from a set of substrate materials composed of silicon and fused silica.

8. The device according to any one of claims 1 to 4, wherein the dielectric layer has a thickness between 50 nm and 500 nm.

9. The film covers the first portion of the optical waveguide, but does not cover the second portion of the optical waveguide. The optical waveguide has a coupler comprising a pair of opposing tip sections that meet at the boundary of the film between the first and second portions. The device according to any one of claims 1 to 4.

10. circuit board and A Mach-Zehnder interferometer arranged on the substrate, First and second optical waveguides, A splitter that receives an input guide light wave and is coupled to split the guide light wave into first and second guide light waves that propagate in the first and second optical waveguides, respectively, and A combiner coupled to receive the first and second guide light waves emitted from the first and second optical waveguides such that the first and second guide light waves interfere to form an output guide light wave, The Mach-Zehnder interferometer includes, A dielectric layer arranged across the first and second optical waveguides on the substrate, A film comprising an electro-optic material arranged across the dielectric layer, covering at least one of the first and second optical waveguides, An electrode configured to modulate the intensity of the output guide light wave by applying an electric field to the electro-optic material near at least one of the first and second optical waveguides, thereby changing the phase difference between the first and second guide light waves, Optoelectronic devices including optoelectronic devices.

11. The device according to claim 10, comprising a controller coupled to apply a voltage between the electrodes in order to generate the electric field.

12. The device according to claim 10, wherein the film covers both the first and second optical waveguides.

13. The device according to claim 12, wherein the electrodes include a first pair of electrodes adjacent to the first optical waveguide and a second pair of electrodes adjacent to the second optical waveguide.

14. The first and second optical waveguides include an optical material having a first intrinsic refractive index, while the electro-optic material has a second intrinsic refractive index greater than the first refractive index. The first and second optical waveguides have a first effective refractive index, the film has a second effective refractive index, and the first and second optical waveguides, the dielectric layer, and the film have dimensions selected such that the first effective refractive index is greater than the second effective refractive index at the wavelength of the guide light wave. The device according to claim 10.

15. The device according to claim 14, wherein the guiding light wave has a wavelength within the visible range of the spectrum.

16. The device according to any one of claims 10 to 15, wherein the electro-optic material comprises barium titanate (BTO).

17. The first and second waveguides include silicon nitride (SiN), and the dielectric material is silicon dioxide (SiO₂ 2 The device according to claim 16, which includes ).

18. The device according to claim 17, wherein the substrate is selected from a set of substrate materials composed of silicon and fused silica.

19. The device according to any one of claims 10 to 15, wherein the dielectric layer has a thickness between 50 nm and 500 nm.

20. The film covers at least one of the first portion of the first and second optical waveguides, but does not cover at least one of the second portion of the first and second optical waveguides. The optical waveguide has at least one coupler including a pair of opposing tip sections that meet at the boundary of the film between the first and second portions. The device according to any one of claims 10 to 15.

21. circuit board and A network of interconnected Mach-Zehnder interferometers arranged on the substrate, wherein each Mach-Zehnder interferometer is First and second optical waveguides, A splitter that receives an input guide light wave and is coupled to split the guide light wave into first and second guide light waves that propagate in the first and second optical waveguides, respectively, and A combiner coupled to receive the first and second guide light waves emitted from the first and second optical waveguides such that the first and second guide light waves interfere to form an output guide light wave, The network of interconnected Mach-Zehnder interferometers, A dielectric layer arranged across a plurality of interconnected Mach-Zehnder interferometers on the substrate, A film comprising adjacent layers of electro-optic material arranged across the dielectric layer, covering at least a portion of the network of the interconnected Mach-Zehnder interferometer, Each of at least a portion of the Mach-Zehnder interferometers includes an electrode configured to apply an electric field to the electro-optic material near at least one of the first and second optical waveguides, A controller coupled to apply a voltage between the electrodes in order to switch the guide light waves passing through the network, A photoelectronic device including a photoelectronic device.

22. The film covers the first portion of the network but does not cover the second portion of the network. At least one of the optical waveguides has a coupler including a pair of opposing tip sections that meet at the boundary of the film between the first and second portions. The apparatus according to claim 21.

23. The apparatus according to claim 22, wherein at least a portion of the Mach-Zehnder interferometer is entirely confined below the film and does not include the opposing tip parts.

24. The first and second optical waveguides include an optical material having a first intrinsic refractive index, while the electro-optic material has a second intrinsic refractive index greater than the first refractive index. The first and second optical waveguides have a first effective refractive index, the film has a second effective refractive index, and the first and second optical waveguides, the dielectric layer, and the film have dimensions selected such that the first effective refractive index is greater than the second effective refractive index at the wavelength of the guide light wave. The apparatus according to claim 21.

25. The apparatus according to claim 24, wherein the guide light wave has a wavelength within the visible range of the spectrum.

26. The apparatus according to any one of claims 21 to 25, wherein the electro-optic material comprises barium titanate (BTO).

27. The first and second waveguides include silicon nitride (SiN), and the dielectric material is silicon dioxide (SiO₂ 2 The apparatus according to claim 26, including ).

28. The apparatus according to claim 27, wherein the substrate is selected from a set of substrate materials composed of silicon and fused silica.

29. The apparatus according to any one of claims 21 to 25, wherein the dielectric layer has a thickness between 50 nm and 500 nm.

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