Optical modulation module

Abstract

This invention discloses an optical modulation module, comprising a substrate, a top cover, an internal laser, a bias control board, an optical switch, a modulator, and an optical splitter. The optical output terminal of the internal laser is connected to the first input terminal of the two-input-one-output optical switch; the external optical input interface is connected to the second input terminal of the optical switch; the output terminal of the optical switch is connected to the optical input terminal of the modulator, and the switching is controlled by the bias control board to achieve flexible selection of internal and external light sources. The modulated optical signal is split into one path by the optical splitter and sent to the bias control board, forming a closed-loop feedback to accurately lock the operating point. The modulator is installed via a vertical mounting plate and a detachable port, enabling convenient replacement and upgrades. This invention, through its highly integrated design, achieves plug-and-play functionality and provides the flexibility of dual-source selection and the maintainability of core components in a single module, significantly improving the application range and economy of the product.

Description

Technical Field

[0001] This utility model relates to the field of optical communication, and in particular to a high-performance optical modulation module. Background Technology

[0002] Optical modulation technology is a key core technology in modern optical communication, fiber optic sensing, microwave photonics, and scientific research. In typical application scenarios, a complete optical modulation link requires the user to prepare the light source (such as a narrow-linewidth laser), optical modulator, bias controller, and various optical and electronic components, and to perform complex optical path splicing and circuit connections. This discrete construction method has the following drawbacks:

[0003] Low system integration and large size: Users need to purchase a variety of independent devices and components, and the system they build occupies a lot of experimental space, which is not conducive to the miniaturization and portability of the system.

[0004] The setup and debugging process is complex and the reliability is poor: users need to have professional skills in fiber optic splicing and RF circuit connection, and the setup process is time-consuming and labor-intensive. There are many connection points between discrete components, and any loosening or contamination at any connection point may lead to a decrease in the performance of the entire system or even failure, making it difficult to guarantee the long-term reliability of the system.

[0005] Limited application flexibility: In certain R&D and testing scenarios, users may want to be able to flexibly switch between the system's built-in stable internal light source and external specific test light sources (such as tunable lasers, special wavelength lasers, etc.). Traditional systems cannot meet this requirement; switching light sources means that the entire optical path needs to be rebuilt and recalibrated.

[0006] Maintenance and upgrades are difficult: As a core component, the bandwidth and operating wavelength of the optical modulator directly determine the performance ceiling of the entire system. In traditional integrated modules, the modulator is usually permanently fixed and fused inside the module. Once damaged or requiring an upgrade to a higher-performance model, the entire module must be scrapped, resulting in huge economic losses and waste of resources. Summary of the Invention

[0007] This invention aims to solve the technical problems of low integration, poor flexibility, and difficulty in maintenance and upgrading existing technologies, and provides a highly integrated, plug-and-play, and more flexible and maintainable high-performance optical modulation module.

[0008] This utility model addresses the aforementioned technical problems primarily through the following technical solution: an optical modulation module comprising a substrate, a top cover, an internal laser, a bias control board, an optical switch, a modulator, an optical splitter, and several interfaces disposed on the substrate. The interfaces include an optical input interface, an optical output interface, an RF input interface, and a power interface. The optical switch is a two-input, one-output optical switch. The internal laser, bias control board, modulator, and optical splitter are fixed within a cavity formed by the substrate and the top cover. The optical output terminal of the internal laser is connected to the first input terminal of the optical switch, the output terminal of the optical switch is connected to the optical input terminal of the modulator, the RF signal terminal of the modulator is connected to the RF signal input interface disposed on the substrate, the optical output terminal of the modulator is connected to the input terminal of the optical splitter, the first output terminal of the optical splitter outputs the main component optical signal to the optical output interface, and the second output terminal of the optical splitter outputs the split component optical signal to the bias control board. The optical input interface is connected to the second input terminal of the optical switch, and the control terminal of the optical switch is connected to the bias control board. The power interface is connected to the bias control board and the internal laser.

[0009] An internal laser (e.g., a narrow-linewidth distributed feedback laser (DFB) serves as an optional light source, with its optical output connected to the first input of the optical switch via a first optical fiber. An external optical input interface (e.g., an FC / APC connector) is connected to the second input of the optical switch via a second optical fiber to receive signals from an external laser source provided by the user.

[0010] The only output of the optical switch is connected to the optical input of the optical modulator. This structure allows the bias control board to selectively transmit internal or external optical signals to the modulator. Upon receiving the optical signal, the modulator's RF signal terminal receives the electrical signal from the external RF signal input interface and modulates the optical signal intensity. The modulated optical signal is output from the modulator's optical output terminal and enters the input of the optical splitter. The optical splitter (e.g., a 10 / 90 or 1 / 99 splitting ratio) divides the modulated optical signal into two paths: the main component optical signal (90% or 99%) is output from its first output terminal and connected to the module's optical output interface as the final product signal output; the split component optical signal (10% or 1%) is output from its second output terminal as a feedback signal, which is then sent to the bias control board for processing. The control terminal of the optical switch is electrically connected to the bias control board, which controls its switching state according to instructions.

[0011] The power interface provides the necessary operating voltage to the bias control board and the internal laser (and its drive circuitry). Through this integrated design, this module achieves dual-source selectable, plug-and-play high-performance optical modulation capabilities within a compact package.

[0012] Preferably, the bias control board includes a main control circuit, a power supply circuit, a scrambling signal generation circuit, a coherent circuit, a bias signal generation circuit, a feedback signal amplification circuit, and a signal mixing circuit. The second output of the optical splitter is connected to the feedback signal amplification circuit through a feedback signal interface. The feedback signal amplification circuit is connected to the input of the coherent circuit, and the output of the coherent circuit is connected to the main control circuit. The inputs of the scrambling signal generation circuit and the bias signal generation circuit are respectively connected to the main control circuit. The outputs of the scrambling signal generation circuit and the bias signal generation circuit are respectively connected to the input of the signal mixing circuit. The output of the signal mixing circuit is connected to the bias signal input of the modulator through a bias signal interface. The main control circuit is also connected to the control terminal of the optical switch.

[0013] The feedback optical signal from the second output of the optical splitter first enters the bias control board through a feedback signal interface, where it is converted into an electrical signal by a photodetector and then amplified by the feedback signal amplification circuit. Simultaneously, the main control circuit drives the scrambling signal generation circuit to generate a low-frequency, small-amplitude sinusoidal "jitter" signal. This jitter signal is superimposed on a DC bias voltage (generated by the bias signal generation circuit) set by the main control circuit in the signal mixing circuit to form the final bias control voltage. This voltage is applied to the modulator through the bias signal interface. Due to the presence of the jitter signal, the feedback optical signal contains harmonic components of this jitter signal related to the modulator's operating point position. The amplified feedback electrical signal and the jitter signal's reference signal are mixed / detected in a coherent circuit, and the detected error signal is sent back to the main control circuit. Based on this error signal, the main control circuit adjusts the DC bias voltage output by the bias signal generation circuit, thus forming a closed-loop feedback that precisely locks the modulator's operating point (such as the quadrature point, peak point, etc.) at a preset position. In addition, the main control circuit is directly connected to the control terminal of the light switch to execute the command for switching the light source.

[0014] Preferably, the substrate is provided with a vertical mounting plate, and the modulator is mounted on the substrate by the vertical mounting plate. The optical input end, optical output end, radio frequency signal end and bias signal input end of the modulator are all detachable connection ports.

[0015] To further enhance the module's flexibility and maintainability, this solution features a specially designed mechanical structure. One or more vertical mounting plates are mounted on the substrate. The optical modulator does not lie directly flat on the substrate but is fixedly connected to the vertical mounting plate via its own mounting holes, forming a "clamp-on" or "vertical mounting" structure. This structure not only facilitates heat dissipation and space allocation but, more importantly, makes modulator replacement feasible. Correspondingly, the optical input, output, RF signal, and bias signal input terminals of the optical modulator all employ detachable connection ports, such as fiber optic connectors (replacing fusion splices), SMA / K type RF connectors, and pluggable electrical connectors. When it is necessary to replace a modulator with a different bandwidth or a damaged one, maintenance personnel only need to disconnect these detachable ports, unscrew the fixing screws, and remove the old modulator to replace it with a new one, greatly reducing maintenance costs and upgrade difficulty.

[0016] Preferably, the modulator is a lithium niobate (MZI) electro-optic modulator. This modulator technology is mature and has advantages such as high bandwidth, low driving voltage, and good extinction ratio, making it an ideal choice for achieving high-performance analog optical transmission.

[0017] Preferably, the internal laser includes a current and temperature controller, a laser source, and a polarization beam splitter. The current and temperature controller outputs a control signal to the laser source. The output of the laser source is connected to the polarization beam splitter via a polarization-maintaining fiber. The polarization beam splitter is connected to the first input of an optical switch via a polarization-maintaining fiber.

[0018] The internal laser is an integrated subsystem that includes a laser source (such as a DFB laser diode), a current and temperature controller (TEC) for stabilizing the laser source wavelength and power, and a polarization beam splitter (PBS) or polarization-maintaining device. The current controller outputs precise drive current and temperature control signals to the laser source according to instructions. The light emitted from the laser source is connected to subsequent devices via a polarization-maintaining fiber (PMF) to ensure that the optical signal entering the optical switch has a stable polarization state, which is crucial for the normal operation of the MZI modulator.

[0019] The beneficial effects of this utility model are:

[0020] 1. Extremely high integration and ease of use: This invention integrates the internal laser source, optical switch, optical modulator, optical splitter, and precision bias control circuitry into a compact and robust cavity, forming a complete "photon transmitter" subsystem. Users no longer need to perform complex fiber optic splicing and circuit connections; they only need to connect the power supply, RF signal, and corresponding fiber optic patch cords to operate, achieving true "plug and play." This greatly simplifies the system setup process, shortens the development cycle, and improves the overall reliability and stability of the system.

[0021] 2. Unprecedented Application Flexibility: By innovatively introducing a two-in-one-out optical switch controlled by a bias control board, this module achieves seamless and rapid switching between internal and external light sources on a single device. Users can utilize the module's stable and reliable internal laser source for routine operations, or easily connect to specific external light sources (such as tunable lasers, ultra-narrow linewidth lasers, etc.) for scientific research or special testing, without requiring any physical modifications to the optical path. This dual-source selectable design greatly expands the module's application scenarios, meeting diverse needs from industrial applications to cutting-edge scientific research.

[0022] 3. Significantly Improved Maintainability and Upgradeability: This invention cleverly solves the pain point of "one-time packaging" of modulators in existing integrated modules by adopting a "vertical mounting plate" mechanical structure and a fully detachable port design. When the core optical modulator is damaged, or when the user needs to upgrade to a modulator with higher bandwidth and a different operating wavelength, it can be easily and quickly replaced, rather than scrapping the entire module. This design not only greatly reduces the user's long-term cost of ownership (TCO) and maintenance costs, but also gives the module future upgrade potential, effectively protecting the user's investment.

[0023] 4. Ensuring Stable Operation with Optimal Performance: The automatic bias control system integrated into this module, through a closed-loop feedback circuit including scrambling and coherent detection functions, can monitor and precisely lock the modulator's operating point in real time, effectively suppressing performance drift caused by changes in ambient temperature and device aging. Combined with the internally integrated laser driver and temperature control circuit, this ensures that the entire module can continuously output high-quality, high-fidelity modulated optical signals under all operating conditions, guaranteeing the stability and consistency of system performance. Attached Figure Description

[0024] Figure 1 This is a structural block diagram of an optical wave modulation module according to this utility model;

[0025] Figure 2 This is a circuit block diagram of a bias control board according to the present invention;

[0026] Figure 3 This is a schematic diagram showing the installation relationship between the modulator and the substrate according to this utility model;

[0027] In the diagram: 1. Internal laser; 2. Bias control board; 3. Modulator; 4. Optical switch; 5. Optical splitter; 6. Optical input interface; 7. RF input interface; 8. Optical output interface; 9. Power interface; 10. Substrate; 11. Vertical mounting plate; 21. Main control circuit; 22. Power circuit; 23. Scrambling signal generation circuit; 24. Coherent circuit; 25. Bias signal generation circuit; 26. Feedback signal amplification circuit; 27. Signal mixing circuit; 28. Feedback signal interface; 29. ​​Bias signal interface. Hollow arrows represent optical signals, and linear arrows represent electrical signals. Detailed Implementation

[0028] The technical solution of this utility model will be further described in detail below through embodiments and in conjunction with the accompanying drawings.

[0029] Example: An optical modulation module according to this embodiment includes a substrate 10, a top cover, an internal laser 1, a bias control board 2, an optical switch 4, a modulator 3, an optical splitter 5, and several interfaces disposed on the substrate. The interfaces include an optical input interface 6, an optical output interface 8, an RF input interface 7, and a power interface 9. The optical switch is a two-input, one-output optical switch. The internal laser, bias control board, modulator, and optical splitter are fixed within a cavity formed by the substrate and the top cover. Figure 1 As shown, the optical output terminal of the internal laser is connected to the first input terminal of the optical switch, the output terminal of the optical switch is connected to the optical input terminal of the modulator, the radio frequency signal terminal of the modulator is connected to the radio frequency signal input interface on the substrate, the optical output terminal of the modulator is connected to the input terminal of the optical splitter, the first output terminal of the optical splitter outputs the main component optical signal to the optical output interface, and the second output terminal of the optical splitter outputs the split component optical signal to the bias control board; the optical input interface is connected to the second input terminal of the optical switch, the control terminal of the optical switch is connected to the bias control board; and the power interface is connected to the bias control board and the internal laser.

[0030] An internal laser (e.g., a narrow-linewidth distributed feedback laser (DFB) serves as an optional light source, with its optical output connected to the first input of the optical switch via a first optical fiber. An external optical input interface (e.g., an FC / APC connector) is connected to the second input of the optical switch via a second optical fiber to receive signals from an external laser source provided by the user.

[0031] The only output of the optical switch is connected to the optical input of the optical modulator. This structure allows the bias control board to selectively transmit internal or external optical signals to the modulator. Upon receiving the optical signal, the modulator's RF signal terminal receives the electrical signal from the external RF signal input interface and modulates the optical signal intensity. The modulated optical signal is output from the modulator's optical output terminal and enters the input of the optical splitter. The optical splitter (with a 1 / 99 splitting ratio) divides the modulated optical signal into two paths: the main component optical signal (99%) is output from its first output terminal and connected to the module's optical output interface as the final product signal output; the split component optical signal (1%) is output from its second output terminal as a feedback signal and sent to the bias control board for processing. The control terminal of the optical switch is electrically connected to the bias control board, which controls its switching state according to instructions.

[0032] The power interface provides the necessary operating voltage to the bias control board and the internal laser (and its drive circuitry). Through this integrated design, this module achieves dual-source selectable, plug-and-play high-performance optical modulation capabilities within a compact package.

[0033] like Figure 2 As shown, the bias control board includes a main control circuit 21, a power supply circuit 22, a scrambling signal generation circuit 23, a coherent circuit 24, a bias signal generation circuit 25, a feedback signal amplification circuit 26, and a signal mixing circuit 27. The second output of the optical splitter is connected to the feedback signal amplification circuit through the feedback signal interface 28. The feedback signal amplification circuit is connected to the input of the coherent circuit, and the output of the coherent circuit is connected to the main control circuit. The inputs of the scrambling signal generation circuit and the bias signal generation circuit are respectively connected to the main control circuit. The outputs of the scrambling signal generation circuit and the bias signal generation circuit are respectively connected to the input of the signal mixing circuit. The output of the signal mixing circuit is connected to the bias signal input of the modulator through the bias signal interface 29. The main control circuit is also connected to the control terminal of the optical switch.

[0034] The feedback optical signal from the second output of the optical splitter first enters the bias control board through a feedback signal interface, where it is converted into an electrical signal by a photodetector and then amplified by the feedback signal amplification circuit. Simultaneously, the main control circuit drives the scrambling signal generation circuit to generate a low-frequency, small-amplitude sinusoidal "jitter" signal. This jitter signal is superimposed on a DC bias voltage (generated by the bias signal generation circuit) set by the main control circuit in the signal mixing circuit to form the final bias control voltage. This voltage is applied to the modulator through the bias signal interface. Due to the presence of the jitter signal, the feedback optical signal contains harmonic components of this jitter signal related to the modulator's operating point position. The amplified feedback electrical signal and the jitter signal's reference signal are mixed / detected in a coherent circuit, and the detected error signal is sent back to the main control circuit. Based on this error signal, the main control circuit adjusts the DC bias voltage output by the bias signal generation circuit, thus forming a closed-loop feedback that precisely locks the modulator's operating point (such as the quadrature point, peak point, etc.) at a preset position. In addition, the main control circuit is directly connected to the control terminal of the light switch to execute the command for switching the light source.

[0035] like Figure 3 As shown, a vertical mounting plate 11 is provided on the substrate. The modulator is mounted on the substrate by the vertical mounting plate, and the optical input end, optical output end, radio frequency signal end and bias signal input end of the modulator are all detachable connection ports.

[0036] To further enhance the module's flexibility and maintainability, this solution features a specially designed mechanical structure. One or more vertical mounting plates are mounted on the substrate. The optical modulator does not lie directly flat on the substrate but is fixedly connected to the vertical mounting plates via its own mounting holes, forming a "clamp-on" or "vertical mounting" structure. This structure not only facilitates heat dissipation and space allocation but, more importantly, makes modulator replacement feasible. Correspondingly, the optical input, output, RF signal, and bias signal input terminals of the optical modulator all employ detachable connection ports. When it is necessary to replace a modulator with a different bandwidth or a damaged one, maintenance personnel only need to disconnect these detachable ports, unscrew the fixing screws, and remove the old modulator to replace it with a new one, significantly reducing maintenance costs and upgrade difficulty.

[0037] The modulator is a lithium niobate (MZI) electro-optic modulator. This modulator technology is mature and has advantages such as high bandwidth, low driving voltage, and good extinction ratio, making it an ideal choice for achieving high-performance analog optical transmission.

[0038] The internal laser includes a current and temperature controller, a laser source, and a polarization beam splitter. The current and temperature controller outputs a control signal to the laser source. The output of the laser source is connected to the polarization beam splitter via a polarization-maintaining fiber. The polarization beam splitter is connected to the first input of an optical switch via a polarization-maintaining fiber.

[0039] The internal laser is an integrated subsystem comprising a laser source (DFB laser diode), a current and temperature controller (TEC) for stabilizing the laser source wavelength and power, and a polarization beam splitter (PBS). The current controller outputs precise drive current and temperature control signals to the laser source according to instructions. The light emitted from the laser source is connected to subsequent devices via a polarization-maintaining fiber (PMF) to ensure that the optical signal entering the optical switch has a stable polarization state, which is crucial for the normal operation of the MZI modulator.

[0040] The specific embodiments described herein are merely illustrative examples illustrating the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the principles of this invention or exceeding the scope defined by the appended claims.

[0041] Although this document uses terms such as modulator, bias control board, and optical splitter frequently, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of this invention; interpreting them as any additional limitation would contradict the spirit of this invention.

Claims

1. An optical wave modulation module, characterized in that, The system includes a substrate, a top cover, an internal laser, a bias control board, an optical switch, a modulator, an optical splitter, and several interfaces mounted on the substrate. These interfaces include an optical input interface, an optical output interface, an RF input interface, and a power interface. The optical switch is a two-input, one-output optical switch. The internal laser, bias control board, modulator, and optical splitter are fixed within a cavity formed by the substrate and the top cover. The optical output of the internal laser is connected to the first input of the optical switch, the output of the optical switch is connected to the optical input of the modulator, the RF signal of the modulator is connected to the RF signal input interface mounted on the substrate, and the optical output of the modulator is connected to the input of the optical splitter. The first output of the optical splitter outputs the main component optical signal to the optical output interface, and the second output of the optical splitter outputs the split component optical signal to the bias control board. The optical input interface is connected to the second input of the optical switch, and the control terminal of the optical switch is connected to the bias control board. The power interface connects to the bias control board and the internal laser.

2. The optical wave modulation module of claim 1, wherein, The bias control board includes a main control circuit, a power supply circuit, a scrambling signal generation circuit, a coherent circuit, a bias signal generation circuit, a feedback signal amplification circuit, and a signal mixing circuit. The second output of the optical splitter is connected to the feedback signal amplification circuit through a feedback signal interface. The feedback signal amplification circuit is connected to the input of the coherent circuit, and the output of the coherent circuit is connected to the main control circuit. The inputs of the scrambling signal generation circuit and the bias signal generation circuit are respectively connected to the main control circuit. The outputs of the scrambling signal generation circuit and the bias signal generation circuit are respectively connected to the input of the signal mixing circuit. The output of the signal mixing circuit is connected to the bias signal input of the modulator through a bias signal interface. The main control circuit is also connected to the control terminal of the optical switch.

3. The optical wave modulation module according to claim 1 or 2, characterized in that, The substrate is provided with a vertical mounting plate, and the modulator is mounted on the substrate by the vertical mounting plate. The optical input end, optical output end, radio frequency signal end and bias signal input end of the modulator are all detachable connection ports.

4. The optical wave modulation module of claim 3, wherein, The modulator is a lithium niobate MZI electro-optic modulator.

5. The optical modulation module according to claim 1, characterized in that, The internal laser includes a current and temperature controller, a laser source, and a polarization beam splitter. The current and temperature controller outputs a control signal to the laser source. The output of the laser source is connected to the polarization beam splitter via a polarization-maintaining fiber. The polarization beam splitter is connected to the first input of an optical switch via a polarization-maintaining fiber.

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