Modulation detection device

Abstract

The invention provides a modulation detection device, which comprises a bottom module, the bottom module comprises a thin film lithium niobate layer, and the thin film lithium niobate layer is provided with: an input optical waveguide suitable for inputting a to-be-processed optical signal; the modulator comprises a modulator electrode, and the modulator is suitable for receiving the optical signal and modulating the phase of the optical signal by using a modulation electric signal sent by the modulator electrode; a wavelength converter configured to convert the wavelength of the modulated optical signal by periodically reversing the crystal orientation of the wavelength converter by applying a voltage to the wavelength converter through a waveguide formed by a periodically polarized thin film lithium niobate layer and by using a nonlinear effect; and the photoelectric detector is suitable for receiving the optical signal after wavelength conversion and converting the optical signal into an electric signal.

Description

Technical Field

[0001] The present disclosure relates to the technical field of integrated optoelectronic devices, and more particularly, to a modulation detection device. Background Art

[0002] Integrated optoelectronic devices make it possible to realize large-scale, low-cost, high-performance optical communications, optical interconnection, optical signal processing and other fields. In integrated optoelectronic devices, modulators and detectors are the core devices. At the same time, modulators and detectors are also used to realize electro-optical and photoelectric conversion.

[0003] The preparation technology of high-performance modulators on thin-film lithium niobate substrates on insulators has become mature. However, due to the large band gap of lithium niobate materials and the absorption band in the ultraviolet band, it is difficult to directly prepare photodetectors compatible with the current infrared optical communication band on it. At present, a technical solution has been proposed to integrate indium phosphide detectors and germanium silicon detectors on thin-film lithium niobate, so that they can complete modulation and detection simultaneously in the communication band. However, indium phosphide detectors have the problem of high cost and the need to improve the yield rate. Germanium silicon detectors also have the problem of complex process and high cost. Pure silicon-based detectors have the advantages of low cost and mature process. They are compatible with CMOS processes and are suitable for large-scale low-cost production. However, their absorption wavelength range is within 400nm-1100nm, which is incompatible with the O band and C band commonly used in current communications.

[0004] Therefore, the technical problem that needs to be solved urgently is how to integrate a pure silicon-based photodetector working in a shorter wavelength band with a modulator working in a longer wavelength band. Summary of the invention

[0005] In order to solve at least one of the above-mentioned and other technical problems in the prior art, the present disclosure provides a modulated detection device that can make the working wavelengths of the modulator and the photodetector compatible and is integrated on a thin-film lithium niobate layer to achieve high performance, low cost and hybrid integration.

[0006] An embodiment of the present disclosure provides a modulation detection device, including a bottom module, wherein the bottom module includes a thin film lithium niobate layer, and the thin film lithium niobate layer is provided with: an input optical waveguide, suitable for inputting an optical signal to be processed; a modulator, wherein the modulator includes a modulator electrode, and the modulator is suitable for receiving the optical signal and modulating the phase of the optical signal using a modulated electrical signal emitted by the modulator electrode; a wavelength converter, which is constructed as a waveguide formed by periodically poling the thin film lithium niobate layer, and by applying a voltage to the wavelength converter, the crystal orientation of the wavelength converter is periodically reversed using a nonlinear effect to convert the wavelength of the modulated optical signal; and a photodetector, which is suitable for receiving the optical signal after wavelength conversion and converting it into an electrical signal.

[0007] According to some embodiments of the present disclosure, the optical signal to be processed includes a single-wavelength optical signal and a multi-wavelength optical signal.

[0008] According to some embodiments of the present disclosure, the wavelength of the optical signal to be processed is 1000nm to 2000nm, and the wavelength of the optical signal after the wavelength conversion is 500nm to 1000nm.

[0009] According to some embodiments of the present disclosure, the input optical waveguide, the modulator, the wavelength converter and the photodetector are respectively connected via waveguides, and the waveguides include an etched thin-film lithium niobate waveguide formed by etching the thin-film lithium niobate layer and a loaded thin-film lithium niobate waveguide formed by growing silicon nitride or silicon on the thin-film lithium niobate layer.

[0010] According to some embodiments of the present disclosure, the waveguide includes a single-mode waveguide and a multi-mode waveguide, the width of the single-mode waveguide is 500nm to 1500nm, and the width of the multi-mode waveguide is 1500nm to 5000nm.

[0011] According to some embodiments of the present disclosure, the waveguide is configured as a stripe type or a ridge type.

[0012] According to some embodiments of the present disclosure, the bottom module further includes: a substrate; an insulating layer disposed on the substrate, and the thin-film lithium niobate layer is disposed on the insulating layer.

[0013] According to some embodiments of the present disclosure, the thin-film lithium niobate layer is provided with an opening, and the photodetector is bonded to a corresponding region of the opening on the insulating layer.

[0014] According to some embodiments of the present disclosure, the photodetector is epitaxially grown on the thin film lithium niobate layer.

[0015] According to some embodiments of the present disclosure, the bottom module is provided with a groove, the groove extends from the thin film lithium niobate layer to the substrate, the insulating layer is prepared at the bottom of the groove, and the photodetector is prepared on the insulating layer.

[0016] According to a modulation detection device provided by the present disclosure, a wavelength converter is set between the modulator and the photodetector, so that the working wavelengths of the modulator and the photodetector can be made compatible, and integrated on a thin film lithium niobate layer, thereby reducing coupling losses and increasing the rate of the modulation signal to achieve high performance, low cost and hybrid integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a structural diagram of a modulation detection device according to an exemplary embodiment of the present disclosure;

[0018] Figure 2 is a cross-sectional view of a bottom module according to an exemplary embodiment of the present disclosure;

[0019] Figure 3 is a cross-sectional view of a photodetector according to an illustrative embodiment of the present disclosure;

[0020] Figure 4 is a cross-sectional view of a photodetector according to another exemplary embodiment of the present disclosure; and

[0021] Figure 5 is a cross-sectional view of a photodetector according to yet another exemplary embodiment of the present disclosure.

[0022] In the drawings, the meanings of the reference numerals are as follows:

[0023] 1. Input optical waveguide;

[0024] 2. Modulator;

[0025] 3. Modulator electrode;

[0026] 4. Wavelength converter;

[0027] 5. Photoelectric detector;

[0028] 6. Thin film lithium niobate layer;

[0029] 7. Insulation layer;

[0030] 8. Substrate. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0032] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0033] All terms used herein, including technical and scientific terms, have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0034] When using expressions such as "at least one of A, B, and C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, and C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc. When using expressions such as "at least one of A, B, or C, etc.", it should generally be interpreted as the meaning of the expression generally understood by those skilled in the art. For example, "a system having at least one of A, B, or C" should include but not be limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.

[0035] According to the concept of one aspect of the present disclosure, a modulation detection device is designed. By setting a wavelength converter between the modulator and the photodetector, the operating wavelengths of the modulator and the photodetector can be made compatible, and the device is integrated on a thin-film lithium niobate layer to reduce coupling losses and increase the rate of the modulation signal, thereby achieving high performance, low cost and hybrid integration.

[0036] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0037] Figure 1 is a structural diagram of a modulation detection device according to an illustrative embodiment of the present disclosure.

[0038] According to an embodiment of the present disclosure, a modulation detection device is provided, comprising a bottom module, the bottom module comprising a thin film lithium niobate layer 6, on which an input optical waveguide 1, a modulator 2, a wavelength converter 4 and a photodetector 5 are arranged. Figure 1 As shown, the input optical waveguide 1 is suitable for inputting the optical signal to be processed. The modulator 2 includes a modulator electrode 3, which is suitable for receiving the optical signal and modulating the phase of the optical signal using the modulated electrical signal emitted by the modulator electrode 3. The wavelength converter 4 is constructed as a waveguide formed by periodically polarizing the thin film lithium niobate layer 6. By applying a voltage to the wavelength converter 4, the crystal orientation of the wavelength converter 4 is periodically reversed using a nonlinear effect to convert the wavelength of the modulated optical signal. The photodetector 5 is suitable for receiving the optical signal after wavelength conversion and converting it into an electrical signal.

[0039] According to the embodiments of the present disclosure, the thickness of the thin film lithium niobate layer 6 is 100nm to 1000nm, and the width of the thin film lithium niobate layer 6 is 1μm. Compared with the existing bulk material platform, for example, the existing bulk lithium niobate substrate, the thickness of the bulk lithium niobate substrate is 10μm, and the width of the thin film lithium niobate layer 6 is reduced by about 10 times, the overall size of the modulation detection device is reduced by about 20 times, the modulation efficiency of the modulator 2 is improved by about 3 times, and the electro-optical bandwidth is improved by about 2 times.

[0040] According to an embodiment of the present disclosure, the modulator 2 may be a Mach-Zehnder interferometer modulator, a plurality of Mach-Zehnder interferometer modulators connected in cascade or in parallel, a micro-ring modulator, or a Bragg phase or intensity modulator.

[0041] According to an embodiment of the present disclosure, the modulator electrode 3 may be gold with a size of 100 nm to 2000 nm, nickel chromium with a size of 10 nm to 500 nm, titanium with a size of 10 nm to 500 nm, or a transparent metal oxide with a size of 10 nm to 1000 nm.

[0042] According to the embodiments of the present disclosure, Figure 1 As shown, multiple modulator electrodes 3 are arranged on both sides of the modulator 2. The modulator 2 utilizes the linear electro-optical effect of the thin film lithium niobate layer 6. By applying voltage to the multiple modulator electrodes 3, the modulator 2 located between the multiple modulator electrodes 3 is placed in an electric field and the refractive index of the modulator 2 is changed, so that the amplitude information of the modulated electrical signal emitted by the modulator electrode 3 is loaded on the phase, amplitude or polarization information of the optical signal, thereby realizing modulation of the optical signal.

[0043] According to an embodiment of the present disclosure, the wavelength converter 4 is constructed as a waveguide formed by periodically poling the thin film lithium niobate layer 6. The wavelength converter 4 is a nonlinear waveguide device. By applying voltage to the wavelength converter 4 and utilizing the nonlinear effect of the thin film lithium niobate layer 6, the crystal orientation of the wavelength converter 4 is periodically reversed to manufacture a periodic domain structure. Under the condition of quasi-phase matching, the wavelength of the modulated optical signal is converted.

[0044] According to the embodiments of the present disclosure, nonlinear effects refer to effects caused by nonlinear polarization of the thin film lithium niobate layer 6 under strong light, including optical harmonics, frequency doubling, stimulated Raman scattering, two-photon absorption, saturation absorption, self-focusing and self-defocusing, etc.

[0045] According to an embodiment of the present disclosure, the wavelength converter 4 is configured in a stripe type or a ridge type, and the waveguide width is 500 nm to 5000 nm.

[0046] According to an embodiment of the present disclosure, the wavelength of the optical signal to be processed is 1000nm to 2000nm, and the wavelength of the optical signal after wavelength conversion is 500nm to 1000nm.

[0047] According to an embodiment of the present disclosure, the photodetector 5 can be a silicon-based photodetector. Due to the characteristics of its band gap width, the silicon-based photodetector responds to optical signals in the 400nm to 1100nm band. The photodetector 5 can respond to optical signals after wavelength conversion and convert the optical signals in this band into electrical signals.

[0048] According to an embodiment of the present disclosure, the silicon-based photodetector includes a junction photodetector. The photodetector 5 made using the photovoltaic effect is a barrier photodetector, and the barrier photodetector is composed of a "junction" that is sensitive to light, and is therefore also called a junction photodetector.

[0049] According to the embodiments of the present disclosure, an input optical waveguide 1, a modulator 2, a wavelength converter 4 and a photodetector 5 are provided on a thin-film lithium niobate layer 6 and integrated into an integrated device. Compared with other integrated optoelectronic material platforms, such as silicon on insulator, indium phosphide and silicon nitride, integration on a thin-film lithium niobate layer 6 can make optoelectronic devices or systems chip-based, and the modulation rate and performance are better than other integrated optoelectronic material platforms. The bandwidth of the modulator 2 is greater than 100 GHz, and the coupling loss is reduced. The end face coupling can be as low as 0.5 dB per end face, which reduces the waveguide loss. The waveguide loss can be as low as 0.1 dB / cm, which can meet the needs of high-speed optoelectronic communications and reduce detection costs.

[0050] According to an embodiment of the present disclosure, the optical signal to be processed includes a single-wavelength optical signal and a multi-wavelength optical signal.

[0051] According to an embodiment of the present disclosure, the input optical waveguide 1, the modulator 2, the wavelength converter 4 and the photodetector 5 are respectively connected by waveguides, and the waveguides include an etched thin-film lithium niobate waveguide formed by etching a thin-film lithium niobate layer 6 and a loaded thin-film lithium niobate waveguide formed by growing silicon nitride or silicon on the thin-film lithium niobate layer 6.

[0052] According to an embodiment of the present disclosure, the waveguide width is 500 nm to 5000 nm.

[0053] According to an embodiment of the present disclosure, the loaded thin-film lithium niobate waveguide includes, but is not limited to, being formed by growing silicon nitride or silicon on the thin-film lithium niobate layer 6 .

[0054] According to an embodiment of the present disclosure, the waveguide includes a single-mode waveguide and a multi-mode waveguide, the width of the single-mode waveguide is 500nm-1500nm, and the width of the multi-mode waveguide is 1500nm-5000nm.

[0055] According to an embodiment of the present disclosure, the waveguide is configured in a stripe type or a ridge type.

[0056] Figure 2is a cross-sectional view of a bottom module according to an exemplary embodiment of the present disclosure.

[0057] According to the embodiments of the present disclosure, Figure 2 As shown, the bottom module further includes a substrate 8 and an insulating layer 7. The insulating layer 7 is disposed on the substrate 8, and the thin-film lithium niobate layer 6 is disposed on the insulating layer 7.

[0058] According to an embodiment of the present disclosure, the material of the substrate 8 includes but is not limited to silicon, quartz, silicon carbide and lithium niobate.

[0059] According to an embodiment of the present disclosure, the material of the insulating layer 7 includes but is not limited to silicon dioxide. The thickness of the insulating layer 7 is 1 μm to 8 μm.

[0060] Figure 3 is a cross-sectional view of a photodetector 5 according to an exemplary embodiment of the present disclosure.

[0061] According to the embodiments of the present disclosure, Figure 3 As shown, the thin-film lithium niobate layer 6 is provided with an opening, and the photodetector 5 is bonded to a corresponding region of the opening on the insulating layer 7 .

[0062] According to the embodiment of the present disclosure, the photodetector 5 is disposed in a corresponding area of ​​the opening on the insulating layer 7 in a bonding manner, which can reduce the cost.

[0063] Figure 4 is a cross-sectional view of a photodetector 5 according to another exemplary embodiment of the present disclosure.

[0064] According to the embodiments of the present disclosure, Figure 4 As shown, the photodetector 5 is epitaxially grown on the thin film lithium niobate layer 6 .

[0065] According to the embodiment of the present disclosure, after a layer of silicon is epitaxially grown on the thin-film lithium niobate layer 6, the photodetector 5 is arranged on the silicon of the thin-film lithium niobate layer 6 by epitaxial growth, which can realize the integrated structure of the modulated detector for high-performance detection.

[0066] Figure 5 is a cross-sectional view of a photodetector 5 according to yet another exemplary embodiment of the present disclosure.

[0067] According to the embodiments of the present disclosure, Figure 5 As shown, the bottom module is provided with a groove, and the groove extends from the thin film lithium niobate layer 6 to the substrate 8. An insulating layer 7 is prepared at the bottom of the groove, and a photodetector 5 is prepared on the insulating layer 7.

[0068] According to the embodiment of the present disclosure, the photodetector 5 is a waveguide device, and a waveguide is generated only when there is a refractive index difference between the insulating layer 7 and the silicon layer where the photodetector 5 is located, so as to prepare the photodetector 5. Therefore, the insulating layer 7 is prepared at the bottom of the groove, and the photodetector 5 is prepared on the insulating layer 7.

[0069] According to the embodiments of the present disclosure, the complexity of the process for preparing the photodetector 5 can be reduced.

[0070] It should also be noted that the directional terms mentioned in the embodiments, such as "upper", "lower", "front", "back", "left", "right", etc., are only reference directions of the drawings and are not intended to limit the scope of protection of the present disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present disclosure, and the shapes and sizes of the components in the drawings do not reflect the actual size and proportion, but only illustrate the contents of the embodiments of the present disclosure.

[0071] Unless otherwise indicated, the numerical parameters in this specification and the appended claims are approximate values ​​and can vary according to the desired properties obtained through the content of the present disclosure. Specifically, all numbers used in the specification and claims to express the content of the composition, reaction conditions, etc., should be understood to be modified by the term "about" in all cases. In general, the meaning of the expression is to include a variation of ±10% in some embodiments, ±5% in some embodiments, ±1% in some embodiments, and ±0.5% in some embodiments by a specific number.

[0072] The ordinal numbers used in the specification and claims, such as "first", "second", "third", etc., to modify the corresponding elements, do not themselves mean that the elements have any ordinal numbers, nor do they represent the order of one element and another element, or the order in the manufacturing method. The use of these ordinal numbers is only used to clearly distinguish a component with a certain name from another component with the same name.

[0073] In addition, unless the steps are specifically described or must occur in sequence, the order of the above steps is not limited to the above list, and can be changed or rearranged according to the required design. And the above embodiments can be mixed and matched with each other or with other embodiments based on design and reliability considerations, that is, the technical features in different embodiments can be freely combined to form more embodiments.

[0074] The embodiments of the present disclosure are described above. However, these embodiments are only for illustrative purposes and are not intended to limit the scope of the present disclosure. Although the embodiments are described above separately, this does not mean that the measures in the various embodiments cannot be used in combination to advantage. The scope of the present disclosure is defined by the attached claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art may make a variety of substitutions and modifications, which should all fall within the scope of the present disclosure.

Claims

1. A modulation detection device, comprising a bottom module, wherein the bottom module comprises a thin film lithium niobate layer, and the thin film lithium niobate layer is provided with: An input optical waveguide, adapted to input an optical signal to be processed; A modulator, the modulator comprising a modulator electrode, the modulator being adapted to receive the optical signal and modulate the phase of the optical signal using a modulated electrical signal emitted by the modulator electrode; A wavelength converter, which is configured as a waveguide formed by periodically poling the thin film lithium niobate layer, and by applying a voltage to the wavelength converter, the crystal orientation of the wavelength converter is periodically reversed by utilizing a nonlinear effect to convert the wavelength of the modulated optical signal; as well as Photoelectric detector, suitable for receiving wavelength-converted optical signals and converting them into electrical signals.

2. The modulation detection device according to claim 1, wherein: The optical signal to be processed includes a single-wavelength optical signal and a multi-wavelength optical signal.

3. The modulation detection device according to claim 1, wherein: The wavelength of the optical signal to be processed is 1000nm-2000nm, and the wavelength of the optical signal after wavelength conversion is 500nm-1000nm.

4. The modulation detection device according to claim 1, wherein: The input optical waveguide, the modulator, the wavelength converter and the photodetector are respectively connected by waveguides, and the waveguides include an etched thin-film lithium niobate waveguide formed by etching the thin-film lithium niobate layer and a loaded thin-film lithium niobate waveguide formed by growing silicon nitride or silicon on the thin-film lithium niobate layer.

5. The modulation detection device according to claim 4, wherein: The waveguide includes a single-mode waveguide and a multi-mode waveguide. The width of the single-mode waveguide is 500nm-1500nm, and the width of the multi-mode waveguide is 1500nm-5000nm.

6. The modulation detection device according to claim 4, wherein: The waveguide is configured in a stripe type or a ridge type.

7. The modulation detection device according to any one of claims 1 to 6, wherein: The bottom module also includes: substrate; The insulating layer is arranged on the substrate, and the thin-film lithium niobate layer is arranged on the insulating layer.

8. The modulation detection device according to claim 7, wherein: The thin-film lithium niobate layer is provided with an opening, and the photodetector is bonded to a corresponding region of the opening on the insulating layer.

9. The modulation detection device according to claim 7, wherein: The photodetector is epitaxially grown on the thin film lithium niobate layer.

10. The modulation detection device according to claim 7, wherein: The bottom module is provided with a groove, and the groove extends from the thin-film lithium niobate layer to the substrate. The insulating layer is prepared at the bottom of the groove, and the photoelectric detector is prepared on the insulating layer.

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