Optical module based on silicon optical chip

Abstract

The utility model belongs to the technical field of optical modules, and provides an optical module based on a silicon optical chip, which comprises an MZ modulator, a spot size converter, a waveguide thermal tuner, a wavelength divider and a photoelectric detector. The output end of the spot size converter is connected with the MZ modulator; the MZ modulator is also connected with the waveguide thermal tuner; the output end of the MZ modulator is connected with the input end of the wavelength splitter; and the wavelength splitter is used for splitting the modulated light output by the MZ modulator into two paths, one path is transmitted to the photoelectric detector, and the other path is output outwards. High-power, long-distance and high-speed optical signal transmission can be realized.

Description

Technical Field

[0001] The utility model belongs to the technical field of optical modules, and in particular relates to an optical module based on a silicon optical chip. Background Art

[0002] The statements in this section merely provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] The optical fiber communication system uses light as a carrier wave, and uses extremely pure glass drawn into extremely fine optical fibers as a transmission medium, and uses light to transmit information through photoelectric conversion. In medium and long-distance optical fiber communication systems, EML (electroabsorption modulation) lasers and DFB (distributed feedback) lasers are currently commonly used, and the modulation methods of these two lasers are affected by temperature drift and frequency chirp effects. In particular, when the signal is transmitted to more than 25Gbps, the influence of factors such as temperature drift and chirp seriously restricts the transmission distance of the optical signal. In addition, the spatial optical coupling method of traditional silicon photonic chips usually uses lens convergence to achieve coupling due to the large difference between silicon photonic chips and optical fiber waveguide mode spots. The structure is relatively complex and direct coupling cannot be achieved. Utility Model Content

[0004] In order to solve the technical problems existing in the above-mentioned background technology, the utility model provides an optical module based on a silicon photonic chip, which can realize high-power, long-distance and high-speed optical signal transmission.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] In one or more embodiments, an optical module based on a silicon photonic chip includes an MZ modulator, a mode spot converter, a waveguide thermal tuner, a wavelength splitter, and a photodetector;

[0007] The output end of the pattern spot converter is connected to the MZ modulator;

[0008] The MZ modulator is also connected to the waveguide thermal tuner;

[0009] The output end of the MZ modulator is connected to the input end of the wavelength divider;

[0010] The wavelength splitter is used to split the modulated light output by the MZ modulator into two paths, one path is transmitted to the photoelectric detector, and the other path is output externally.

[0011] As an implementation mode, the optical module based on the silicon photonic chip further includes a laser, a current source circuit, a voltage follower, an MZ driver and a mirror circuit;

[0012] The output end of the laser is connected to the input end of the spot converter;

[0013] The current source circuit is connected to the laser;

[0014] The voltage follower is connected to the waveguide thermal tuner;

[0015] The MZ driver is connected to the MZ modulator;

[0016] The mirror circuit is connected to the photodetector.

[0017] As an implementation manner, the MZ driver is a differential AC coupling drive circuit.

[0018] As an implementation mode, the differential AC coupling driving circuit includes a driving chip and a differential AC coupling circuit; the differential AC coupling circuit is composed of two sub-circuits with the same structure connected to two output terminals of the driving chip; each sub-circuit is composed of an RL parallel network composed of a first resistor and a first inductor, and a second inductor and a first capacitor in series; the RL parallel network is also connected to a power supply; one end of the first capacitor is connected to the output terminal of the driving chip, and the other end is connected to the input terminal of the MZ modulator.

[0019] As an embodiment, the mirror circuit includes a first transistor, a second transistor and a second resistor, the first transistor and the second transistor are arranged in a mirror image relative to each other, the base terminals of the two are directly connected, the emitter terminals of the two are connected to a power supply, the collector terminal of the first transistor is connected to one end of the photoelectric detection, the collector terminal of the second transistor is connected to the other end of the photoelectric detection through the second resistor, and the end of the second resistor connected to the photoelectric detection is also grounded.

[0020] As an implementation mode, the current source circuit is composed of a current source type driver chip and its peripheral circuits.

[0021] As an implementation mode, the MZ driver, the current source circuit and the voltage follower are all connected to a controller.

[0022] As an implementation manner, the laser is directly end-face coupled to the input end of the spot converter.

[0023] As an implementation, the photodetector is a PD photodetector.

[0024] As an implementation mode, the output end of the pattern spot converter is connected to the MZ modulator through a waveguide.

[0025] The beneficial effects of the utility model are:

[0026] (1) The utility model integrates optical components such as MZ modulator, mode spot converter, waveguide thermal tuner, wavelength splitter and photodetector, which effectively improves the complexity of the device optical path and saves device packaging space.

[0027] (2) The utility model adopts an MZ modulator that is driven only when the refractive index changes of the two arms are equal and opposite, which solves the frequency chirp problem of DML and EAM and is suitable for long-distance and DWDM environment applications.

[0028] (3) The MZ modulator of the utility model is also connected to a waveguide thermal tuner, and the waveguide thermal tuner is used to achieve locking of the optimal phase and eye diagram performance.

[0029] (4) The utility model adopts end-face coupling between the laser and the spot converter, which can effectively reduce the spatial distance limitation without the need for a lens, and increases the spot of the laser output through the spot converter, thereby improving the incident power coupling efficiency.

[0030] (5) The MZ driver of the present invention adopts a differential AC coupling driving circuit, which can achieve a differential modulation amplitude of 4Vpp and an extinction ratio performance of more than 8dB.

[0031] (6) The optical module based on silicon photonic chip of the utility model is suitable for single-carrier, long-distance transmission optical module packaging system with a rate of 25Gbps / 50Gpbs / 100Gbps, such as the next-generation 25G / 50G / 100G DWDM network application.

[0032] Advantages of additional aspects of the present invention will be partially given in the following description, and partially become apparent from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention.

[0034] Figure 1 This is a schematic diagram of an optical module based on a silicon photonic chip according to an embodiment of the present utility model;

[0035] Figure 2 This is a circuit diagram of an optical module based on a silicon photonic chip according to an embodiment of the utility model. DETAILED DESCRIPTION

[0036] The utility model is further described below in conjunction with the accompanying drawings and embodiments.

[0037] It should be noted that the following detailed descriptions are all exemplary and are intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0038] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the utility model. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0039] Figure 1 This is a schematic diagram of an optical module based on a silicon photonic chip according to an embodiment of the utility model. Figure 1 An optical module based on a silicon photonic chip in an embodiment of the utility model includes an MZ modulator, a pattern spot converter, a waveguide thermal tuner, a wavelength divider and a photodetector; the output end of the pattern spot converter is connected to the MZ modulator; the MZ modulator is also connected to the waveguide thermal tuner; the output end of the MZ modulator is connected to the input end of the wavelength divider; the wavelength divider is used to divide the modulated light output by the MZ modulator into two paths, one path is transmitted to the photodetector, and the other path is output to the outside.

[0040] In this embodiment, the MZ modulator is an electro-optic modulator based on the Mach-Zehnder interference principle. Its principle is to achieve amplitude modulation based on constructive interference and destructive interference of light. The input single-mode light source is divided into two equal energy paths by the input beam splitter, and then passes through the upper and lower phase shifters to produce different phase shifts; finally, the two paths of light are superimposed together through the output combiner. If the two paths of light are in phase, the energy is constructive after the light is superimposed, and the output is 1; if the two paths of light are in anti-phase, the energy is destructive after the light is superimposed, and the output is 0. Moreover, the structure of the MZ modulator is an existing structure, and technicians in this field can select a specific model according to actual conditions.

[0041] In this embodiment, the output end of the spot converter is connected to the MZ modulator through a waveguide.

[0042] Specifically, the spot converter is generally divided into horizontal cone and vertical cone, which are used to change the shape of the light spot. The model of the spot converter can be specifically selected by those skilled in the art according to actual conditions.

[0043] The spot converter of this embodiment is used to change the shape of the laser output spot and improve the incident power coupling efficiency.

[0044] In this embodiment, the structure of the waveguide thermal tuner is an existing structure, and those skilled in the art may select a specific model according to actual conditions.

[0045] The role of the waveguide thermal tuner is to achieve lock for optimum phase and eye diagram performance.

[0046] In this embodiment, the wavelength splitter is used to distribute the corresponding energy of the light modulated by the MZ modulator.

[0047] The structure of the wavelength splitter is an existing structure. For example, the wavelength splitter can be a 1:2 wavelength splitter or a 1:1 wavelength splitter, etc. Those skilled in the art can select a specific model according to actual conditions.

[0048] The photodetector of this embodiment is a PD (photodiode) photodetector, which has the advantages of high quantum efficiency, low noise, wide spectrum response and fast response speed; its structure is an existing structure, and technicians in this field can select a specific model according to actual conditions, which will not be described in detail here.

[0049] In one or more embodiments, the optical module based on the silicon photonic chip also includes a laser, a current source circuit, a voltage follower, an MZ driver and a mirror circuit; the output end of the laser is connected to the input end of the mode spot converter; the current source circuit is connected to the laser; the voltage follower is connected to the waveguide thermal tuner; the MZ driver is connected to the MZ modulator; and the mirror circuit is connected to the photodetector.

[0050] exist Figure 2 In the MZ modulator, the spot converter, the waveguide thermal tuner, the wavelength splitter and the photodetector constitute the MZ modulation module, which is represented by U3. The current source circuit is composed of a current source type driver chip and its peripheral circuits. Among them, the current source type driver chip is represented by U4; there are two voltage followers, each consisting of two amplifiers. Figure 2 In the figure, U1 and U5 are used to represent them respectively and are arranged at both ends of the thermal conductive tuner.

[0051] In this embodiment, the laser may be a CW DFB laser. The white light output by the CW DFB laser is indirectly modulated by an MZ modulator, which effectively eliminates the influence of frequency chirp and temperature drift. The optical signal can achieve a higher signal-to-noise ratio and wavelength accuracy, and improves the inter-symbol interference problem caused by wavelength drift and optical dispersion.

[0052] In this embodiment, the mirror circuit includes a first transistor Q1, a second transistor Q2 and a second resistor R2. The first transistor Q1 and the second transistor Q2 are arranged in a mirror image relative to each other, the base terminals of the two are directly connected, the emitter terminals of the two are connected to the power supply, the collector terminal of the first transistor Q1 is connected to one end of the photoelectric detection, the collector terminal of the second transistor Q2 is connected to the other end of the photoelectric detection through the second resistor R2, and the end of the second resistor R2 connected to the photoelectric detection is also grounded.

[0053] In this embodiment, the MZ driver, the current source circuit and the voltage follower are all connected to the controller. For example, the controller is connected to the MZ driver, the current source circuit and the voltage follower respectively through an I2C serial communication circuit.

[0054] The structure of the controller here is an existing structure, and the process of controlling the output signals of the MZ driver, the current source circuit and the voltage follower is an existing procedure. Those skilled in the art can select a specific model of the controller according to actual accuracy requirements.

[0055] exist Figure 2 In the embodiment, the voltage followers U1 and U5 are respectively connected to the DAC1 interface and the DAC2 interface of the controller. The voltage followers U1 and U5 are used to drive the waveguide thermal tuner in the MZ external modulation silicon photonic chip U3.

[0056] In one or more embodiments, the controller is also connected to the output terminal Vmpd of the mirror circuit. Since the photodetector monitors the magnitude of the current output through the mirror circuit, the controller can monitor the intensity of the emitted light power by sampling the output signal of the mirror circuit.

[0057] In some specific implementations, the laser is directly end-face coupled to the input end of the spot converter, which eliminates the need for a lens and effectively reduces spatial distance limitations.

[0058] Preferably, the MZ driver is a differential AC-coupled driving circuit.

[0059] Specifically, the differential AC coupling driving circuit includes a driving chip U2 and a differential AC coupling circuit;

[0060] The differential AC coupling circuit is composed of two sub-circuits with the same structure connected to two output terminals (e.g., TXOP terminal and TXON terminal) of the driver chip U2;

[0061] Each sub-circuit is composed of an RL parallel network composed of a first resistor R1 and a first inductor L1, a second inductor L2 and a first capacitor C1 in series; the RL parallel network is also connected to a power supply VCC; one end of the first capacitor C1 is connected to an output terminal of the driver chip U2, and the other end is connected to an input terminal of the MZ modulator.

[0062] In this embodiment, the working principle of the optical module is:

[0063] The current source circuit (U4) drives the laser to output white light, which is coupled into the pin port of the MZ external modulation silicon photonic chip (U3) through the end face and shrinks the light spot through the mode spot converter to enter the silicon waveguide and be transmitted to the MZ modulator;

[0064] The MZ modulator (TX_IN+ / TX_IN-) modulates the amplitude or phase of the light and then outputs it; wherein the MZ modulator achieves optimal phase and eye diagram performance locking under the action of the waveguide thermal regulator; and the MZ modulator works under the driving action of the MZ driver;

[0065] After the light output by the MZ modulator passes through the optical splitter, one of the light paths is directly transmitted to the photodetectors (PD+, PD-) to monitor the emitted light power; the other light path forms an optical signal (Pout) and is converged and coupled into the optical fiber for transmission through a lens;

[0066] Among them, the output signal size of the MZ driver is controlled by the controller, and the controller also controls the voltage follower to drive the waveguide thermal regulator; the photodetector monitors the current size through the mirror circuit output, and the controller monitors the emission light power intensity by sampling the output signal of the mirror circuit, and then adjusts the output signal size of the current source circuit according to the monitored emission light power intensity to ensure the stability of the optical signal transmitted by the optical module.

[0067] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. An optical module based on a silicon photonic chip, characterized in that: Including MZ modulators, mode spot converters, waveguide thermal tuners, wavelength splitters and photodetectors; The output end of the pattern spot converter is connected to the MZ modulator; The MZ modulator is also connected to the waveguide thermal tuner; The output end of the MZ modulator is connected to the input end of the wavelength divider; The wavelength splitter is used to split the modulated light output by the MZ modulator into two paths, one path is transmitted to the photoelectric detector, and the other path is output externally.

2. The optical module based on silicon photonic chip according to claim 1, characterized in that: The optical module based on the silicon photonic chip also includes a laser, a current source circuit, a voltage follower, an MZ driver and a mirror circuit; The output end of the laser is connected to the input end of the spot converter; The current source circuit is connected to the laser; The voltage follower is connected to the waveguide thermal tuner; The MZ driver is connected to the MZ modulator; The mirror circuit is connected to the photodetector.

3. The optical module based on silicon photonic chip according to claim 2, characterized in that: The MZ driver is a differential AC coupling driving circuit.

4. The optical module based on silicon photonic chip as claimed in claim 3, characterized in that: The differential AC coupling driving circuit includes a driving chip and a differential AC coupling circuit; the differential AC coupling circuit is composed of two sub-circuits with the same structure connected to the two output terminals of the driving chip; each sub-circuit is composed of an RL parallel network composed of a first resistor and a first inductor, and a second inductor and a first capacitor in series; the RL parallel network is also connected to a power supply; one end of the first capacitor is connected to the output terminal of the driving chip, and the other end is connected to the input terminal of the MZ modulator.

5. The optical module based on silicon photonic chip according to claim 2, characterized in that: The mirror circuit includes a first transistor, a second transistor and a second resistor. The first transistor and the second transistor are arranged in a mirror image relative to each other, the base terminals of the two are directly connected, the emitter terminals of the two are connected to a power supply, the collector terminal of the first transistor is connected to one end of the photoelectric detection, the collector terminal of the second transistor is connected to the other end of the photoelectric detection through the second resistor, and the end of the second resistor connected to the photoelectric detection is also grounded.

6. The optical module based on silicon photonic chip according to claim 2, characterized in that: The current source circuit is composed of a current source type driving chip and its peripheral circuits.

7. The optical module based on silicon photonic chip according to claim 2, characterized in that: The MZ driver, the current source circuit and the voltage follower are all connected to the controller.

8. The optical module based on silicon photonic chip according to claim 2, characterized in that: The laser is directly end-face coupled to the input end of the spot converter.

9. The optical module based on silicon photonic chip according to claim 1, characterized in that: The photodetector is a PD photodetector.

10. The optical module based on silicon photonic chip according to claim 1, characterized in that: The output end of the pattern spot converter is connected to the MZ modulator through a waveguide.

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