An optical power monitoring device for an EML chip

Abstract

The utility model discloses a kind of optical power monitoring devices of EML chip, including monitoring unit, EML chip monitoring circuit;Wherein: monitoring unit generates response voltage, and is output to the EML chip monitored by EML chip monitoring circuit;EML chip monitoring circuit gathers the feedback current generated by EML chip, and it is sent to monitoring unit, to calculate the optical power of EML chip.The device realizes the accurate monitoring of EML chip optical power, and simple structure is favorable to optical module reduces cost and lightweight design.

Description

Technical Field

[0001] This utility model relates to the field of high-speed optical modules, specifically to an optical power monitoring device for an EML chip. Background Technology

[0002] As optical communication evolves towards higher speeds, smaller sizes, and lower power consumption, real-time monitoring of the internal operating status of optical modules is necessary to prevent bit errors. Digital diagnostic monitoring (DDM) technology ensures link stability by monitoring five core parameters (voltage, temperature, transmit / receive optical power, and bias current).

[0003] The most common approach for adjusting or compensating the drive current at the optical transmitter end of current high-speed optical modules is a backlight monitoring structure: a monitoring photodiode (MPD) is connected to the end of the optical chip, and the laser output is detected and monitored through the feedback current from the MPD. The laser driver determines and adjusts the laser output power based on its feedback current value.

[0004] The drawback of the existing optical power monitoring method is that, since a monitoring photodiode is used, it is necessary to set up auxiliary circuits related to the monitoring photodiode to enable it to work properly. The overall components of the monitoring part are numerous and complex, which is not conducive to the miniaturization design and cost control of optical modules. Utility Model Content

[0005] The purpose of this invention is to provide an optical power monitoring device for EML chips, so as to achieve low-cost and lightweight monitoring of the optical power of EML chips.

[0006] To solve the above-mentioned technical problems, this utility model provides an optical power monitoring device for an EML chip, including a monitoring unit and an EML chip monitoring circuit; wherein:

[0007] The monitoring unit generates a response voltage and outputs it to the monitored EML chip through the EML chip monitoring circuit; the EML chip monitoring circuit collects the feedback current generated by the EML chip and sends it to the monitoring unit to calculate the optical power of the EML chip.

[0008] According to the above scheme, the EML chip monitoring circuit includes a signal filtering module, a first amplification module, a current sampling module, and a second amplification module. The signal filtering module filters the response voltage output by the monitoring unit, the first amplification module amplifies the filtered response voltage, the response voltage amplified by the first amplification module is output to the EML chip through the current sampling module, the current sampling module collects the feedback current of the EML chip and converts it into a feedback voltage, the second amplification module amplifies the feedback voltage and outputs it to the monitoring unit, and the monitoring unit obtains the optical power of the EML chip based on the voltage output by the second amplification module.

[0009] According to the above scheme, the signal filtering module includes capacitor C3, which is connected between ground and the input terminal of the EML chip monitoring circuit; the input terminal of the EML chip monitoring circuit is connected to the response voltage output by the monitoring unit.

[0010] According to the above scheme, the first amplification module includes an operational amplifier U1, a capacitor C1, a resistor R1, and a resistor R2; the inverting input terminal of the operational amplifier U1 is connected to the response voltage output by the monitoring unit through the resistor R1, the non-inverting input terminal of the operational amplifier U1 is grounded, and the capacitor C1 and the resistor R2 are connected in parallel between the inverting input terminal and the output terminal of the operational amplifier U1; the output terminal of the operational amplifier U1 outputs the amplified response voltage.

[0011] According to the above scheme, the current sampling module includes a resistor R7, which is connected between the output terminal of the first amplification module and the EML chip; the feedback current forms a voltage difference across the resistor R7, thereby the resistor R7 converts the feedback current into a feedback voltage.

[0012] According to the above scheme, the second amplification module includes operational amplifier U2, resistors R3, R4, R5, and R6; the inverting input terminal of operational amplifier U2 is connected to the response voltage amplified by the first amplification module through resistor R3, and is connected to the output terminal of operational amplifier U2 through resistor R5; the non-inverting input terminal of operational amplifier U2 is connected to the EML chip through resistor R4, and is connected to the output terminal of operational amplifier U2 through resistor R5; the non-inverting and inverting input terminals of operational amplifier U2 receive feedback voltages, which are amplified by operational amplifier U2 and output at the output terminal of operational amplifier U2.

[0013] According to the above scheme, it includes an alarm unit and a real-time reporting unit; the alarm unit sets the optical power operating range in the monitoring unit, and issues an alarm when the acquired optical power exceeds the preset range, while monitoring the optical power and reporting the specific value in real time according to the CMIS protocol.

[0014] According to the above scheme, it includes a feedback adjustment unit; when the optical power obtained by the monitoring unit exceeds the preset range, the feedback adjustment unit adjusts the response voltage output by the monitoring unit and / or the driving current output by the laser driving unit so that the adjusted optical power is within the preset range; wherein the laser driving unit drives the EML chip.

[0015] According to the above scheme, the alarm unit includes a storage module; the storage module stores the optical power value obtained by the monitoring unit.

[0016] Beneficial effects

[0017] This invention utilizes the characteristic of the electro-absorption modulator in the EML chip that generates feedback current due to the intake of laser light. By collecting the feedback current, the optical power of the laser in the EML chip is obtained. This solution eliminates the monitoring photodiode and related circuits in traditional optical power monitoring solutions, reducing the hardware cost and integration complexity of the optical module, and is conducive to the miniaturization design of the optical module.

[0018] Furthermore, by setting up a signal filtering module, noise is filtered out from the response voltage of the input EML chip to avoid noise interfering with optical modulation and optical power detection.

[0019] Furthermore, by setting a first amplification module to amplify the response voltage of the input EML chip, the signal driving capability of the response voltage is enhanced.

[0020] Furthermore, by setting the feedback voltage obtained by the current sampling module of the second amplification module to be amplified, the ability to capture subtle changes in the feedback current is improved, thereby enhancing the resolution of optical power monitoring.

[0021] Furthermore, by setting up alarm units and feedback adjustment units, alarms and feedback adjustments can be made when the monitored optical power exceeds the set range, thereby achieving fault reminders and stable output of optical power. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of an optical power monitoring device for an EML chip according to an embodiment of the present invention;

[0023] Figure 2 This is a circuit diagram of an optical power monitoring device for an EML chip according to an embodiment of the present invention;

[0024] Figure 3 This is a control principle diagram of an EML chip optical power monitoring device according to an embodiment of this utility model. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0026] See Figure 1 , Figure 2 This embodiment discloses an optical power monitoring device for an EML chip, so as to achieve low-cost and lightweight monitoring of the optical power of the EML chip.

[0027] To solve the above-mentioned technical problems, this utility model provides an optical power monitoring device for an EML chip, such as... Figure 1 It includes a monitoring unit and an EML chip monitoring circuit; wherein:

[0028] The monitoring unit generates a response voltage and outputs it to the monitored EML chip through the EML chip monitoring circuit; the EML chip monitoring circuit collects the feedback current generated by the EML chip and sends it to the monitoring unit to calculate the optical power of the EML chip.

[0029] Figure 1 , Figure 2 In this process, the EML chip includes an electroabsorption modulator and a DFB laser, and the laser driving unit generates a driving current to drive the EML chip.

[0030] The electro-absorption modulator has one end connected to the response voltage amplified by the first amplification module and the other end grounded; the DFB laser has one end connected to the output current of the laser driving unit and the other end grounded; the DFB laser generates laser light under the drive current output by the laser driving unit, and the laser light enters the electro-absorption modulator. The electro-absorption modulator modulates the incoming laser light based on the response voltage amplified by the first amplification module. During the modulation process, the electro-absorption modulator generates a feedback current, the magnitude of which is related to the optical power of the incoming laser light. It should be understood that the electro-absorption modulator, the DFB laser, and the laser driving unit respectively correspond to... Figure 2 The components are EA, Laser U3, and Laser Driver.

[0031] Furthermore, the EML chip monitoring circuit includes a signal filtering module, a first amplification module, a current sampling module, and a second amplification module. The signal filtering module filters the response voltage output by the monitoring unit, the first amplification module amplifies the filtered response voltage, and the amplified response voltage is output to the EML chip via the current sampling module. The current sampling module collects the feedback current of the EML chip and converts it into a feedback voltage. The second amplification module amplifies the feedback voltage and outputs it to the monitoring unit. The monitoring unit obtains the optical power of the EML chip based on the voltage output by the second amplification module.

[0032] Furthermore, the signal filtering module includes capacitor C3, which is connected between ground and the input terminal of the EML chip monitoring circuit; the input terminal of the EML chip monitoring circuit is connected to the response voltage output by the monitoring unit.

[0033] Furthermore, the first amplification module includes an operational amplifier U1, a capacitor C1, a resistor R1, and a resistor R2; the inverting input terminal of the operational amplifier U1 is connected to the response voltage output by the monitoring unit through the resistor R1, the non-inverting input terminal of the operational amplifier U1 is grounded, and the capacitor C1 and the resistor R2 are connected in parallel between the inverting input terminal and the output terminal of the operational amplifier U1; the output terminal of the operational amplifier U1 outputs the amplified response voltage.

[0034] Furthermore, the current sampling module includes a resistor R7, which is connected between the output of the first amplification module and the EML chip; the feedback current forms a voltage difference across the resistor R7, thereby the resistor R7 converts the feedback current into a feedback voltage.

[0035] Furthermore, the second amplification module includes operational amplifier U2, resistors R3, R4, R5, and R6; the inverting input terminal of operational amplifier U2 is connected to the response voltage amplified by the first amplification module through resistor R3, and is connected to the output terminal of operational amplifier U2 through resistor R5; the non-inverting input terminal of operational amplifier U2 is connected to the EML chip through resistor R4, and is connected to the output terminal of operational amplifier U2 through resistor R5; the non-inverting and inverting input terminals of operational amplifier U2 receive feedback voltages, which are amplified by operational amplifier U2 and output at the output terminal of operational amplifier U2.

[0036] Furthermore, it includes an alarm unit and a real-time reporting unit; the alarm unit sets the optical power operating range in the monitoring unit, and issues an alarm when the acquired optical power exceeds the preset range, while simultaneously monitoring the optical power and reporting the specific value in real time according to the CMIS protocol.

[0037] Furthermore, it includes a feedback adjustment unit; when the optical power acquired by the monitoring unit exceeds the preset range, the feedback adjustment unit adjusts the response voltage output by the monitoring unit and / or the drive current output by the laser drive unit so that the adjusted optical power is within the preset range; wherein the laser drive unit drives the EML chip.

[0038] Furthermore, the alarm unit includes a storage module; the storage module stores the optical power value acquired by the monitoring unit.

[0039] In other embodiments of this invention, the monitoring unit, alarm unit, and feedback adjustment unit are all integrated into a microprocessor (MCU). See also Figure 3The microprocessor operates as follows: the voltage set by the MCU's DAC is sent to the EA control unit to make the EML output optical power reach the target value. Then, the voltage value output by the control unit is sent to the MCU. The MCU reads the ADC value, calculates the EML output optical power, and reports the DDM TX power according to the MSA protocol requirements. At the same time, when the EML output optical power changes, the EA current will also change accordingly. The output voltage is adjusted by the MCU's DAC to ensure the laser output is stable, forming an automatic power control loop, and finally achieving stable output optical power.

[0040] Through testing, the solution of this utility model can be applied to 400G / 800G optical modules to modulate optical signals with low chirp and high linearity. In this embodiment, the response current of EA in the EML of the device is fed back to the control circuit for Tx Power monitoring, and can also dynamically compensate for wavelength drift caused by temperature fluctuations, ensuring signal integrity during single-mode fiber transmission. The specific operation process is as follows:

[0041] 1) A constant driving current is continuously output to the laser driver chip module so that the DFB laser can generate a continuous laser with a stable wavelength;

[0042] 2) The data electrical signal is applied to the electrodes of the EAM to form a reverse bias voltage; the voltage change causes the absorption coefficient of the EAM to change periodically, thereby modulating the intensity of the transmitted light. The modulated optical signal is output through the waveguide and transmitted through the optical fiber.

[0043] 3) When the electroabsorption modulator (EAM) modulates the optical signal, it generates a feedback current signal. This signal is converted into a voltage signal by the sampling resistor (i.e., resistor R7) and then input into the ADC module. The microprocessor (MCU) collects the voltage value after the ADC conversion and performs calibration calculations in conjunction with the pre-stored laser PI curve (optical power-current characteristic curve) to eliminate temperature drift and nonlinear errors.

[0044] 4) At the same time, the MCU writes the calibrated Tx Power value into the DDM register and sets the threshold alarm function; when the optical power is detected to exceed the preset range, the LOS (signal loss) or Tx_Fault (transmission failure) flag is immediately triggered; combined with DDM parameters such as Vcc (operating voltage) and temperature, the link status is comprehensively analyzed to realize fault prediction and location (such as laser aging can be warned by abnormal rise in bias current).

[0045] It should be understood that in existing technologies, direct modulated lasers (DMLs) using backlight monitoring are prone to frequency chirping during high-speed modulation, leading to broadening of the optical signal spectrum and reducing the accuracy and stability of backlight monitoring. Furthermore, they exhibit high dispersion over long distances (>10km), requiring additional compensation algorithms and increasing hardware complexity. The wavelength drift of DMLs is temperature-sensitive (approximately 0.1nm / ℃), necessitating the integration of additional temperature compensation circuitry to maintain the reliability of backlight monitoring data. In contrast, this solution employs an electro-absorption modulated laser (EML), which integrates an electro-absorption modulator (EAM) and a DFB laser (LD). Compared to direct modulated lasers, this approach offers superior performance: longer transmission distance, lower chirping, and less dispersion overhead. EAM is based on the quantum confined Stark effect (QCSE). During modulation, the laser maintains a constant current (CW mode), avoiding wavelength drift (chirping effect) caused by changes in carrier concentration, and significantly reducing spectral broadening. It has better modulation linearity. Combined with the low chirping characteristics of EAM, it can achieve a longer transmission distance and supports more complex modulation formats. Through the current monitoring of EAM (EA, as the forward output of the laser, can more accurately monitor the optical power of the laser than backlight detection, with higher monitoring accuracy), combined with microcontroller (MCU) and feedback algorithm, it can monitor optical power fluctuations in real time with higher accuracy, and compensate by adjusting the EAM bias voltage or laser drive current.

[0046] In summary, this utility model has at least the following beneficial effects during application:

[0047] 1. During modulation, the laser maintains a constant current (CW mode), avoiding wavelength drift (chirp effect) caused by changes in carrier concentration, and significantly reducing spectral broadening;

[0048] 2. It has better modulation linearity, and combined with the low chirp characteristics of EAM, it can achieve a longer transmission distance and supports more complex modulation formats.

[0049] 3. Compared with traditional DFB, it reduces MPD and has a cost advantage. It can monitor optical power fluctuations in real time with higher accuracy and can be compensated by adjusting the EAM bias voltage or laser drive current.

[0050] It should be noted that, depending on the implementation needs, the various steps / components described in this application can be broken down into more steps / components, or two or more steps / components or parts of the operation of steps / components can be combined into new steps / components to achieve the purpose of this utility model.

[0051] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. An optical power monitoring device for an EML chip, characterized in that, Includes a monitoring unit and an EML chip monitoring circuit; among which: The monitoring unit generates a response voltage and outputs it to the monitored EML chip through the EML chip monitoring circuit; the EML chip monitoring circuit collects the feedback current generated by the EML chip and sends it to the monitoring unit to calculate the optical power of the EML chip.

2. The optical power monitoring device of the EML chip according to claim 1, wherein, The EML chip monitoring circuit includes a signal filtering module, a first amplification module, a current sampling module, and a second amplification module. The signal filtering module filters the response voltage output by the monitoring unit, the first amplification module amplifies the filtered response voltage, and the amplified response voltage is output to the EML chip via the current sampling module. The current sampling module collects the feedback current of the EML chip and converts it into a feedback voltage. The second amplification module amplifies the feedback voltage and outputs it to the monitoring unit. The monitoring unit obtains the optical power of the EML chip based on the voltage output by the second amplification module.

3. The optical power monitoring device of the EML chip according to claim 2, wherein, The signal filtering module includes capacitor C3, which is connected between ground and the input terminal of the EML chip monitoring circuit; the input terminal of the EML chip monitoring circuit is connected to the response voltage output by the monitoring unit.

4. The optical power monitoring device of the EML chip according to claim 2, wherein, The first amplification module includes an operational amplifier U1, a capacitor C1, a resistor R1, and a resistor R2. The inverting input of the operational amplifier U1 is connected to the response voltage output by the monitoring unit through the resistor R1, the non-inverting input of the operational amplifier U1 is grounded, and the capacitor C1 and the resistor R2 are connected in parallel between the inverting input and the output of the operational amplifier U1. The output of the operational amplifier U1 outputs the amplified response voltage.

5. The optical power monitoring device of the EML chip according to claim 2, wherein, The current sampling module includes a resistor R7, which is connected between the output of the first amplification module and the EML chip. The feedback current forms a voltage difference across the resistor R7, thereby converting the feedback current into a feedback voltage.

6. The optical power monitoring device of the EML chip according to claim 2 or 5, wherein, The second amplification module includes operational amplifier U2, resistors R3, R4, R5, and R6. The inverting input of operational amplifier U2 is connected to the response voltage amplified by the first amplification module via resistor R3, and is connected to the output of operational amplifier U2 via resistor R5. The non-inverting input of operational amplifier U2 is connected to the EML chip via resistor R4, and is connected to the output of operational amplifier U2 via resistor R5. The non-inverting and inverting inputs of operational amplifier U2 receive feedback voltages, which are amplified by operational amplifier U2 and output at the output of operational amplifier U2.

7. The optical power monitoring device for an EML chip according to claim 1, characterized in that, It includes an alarm unit and a real-time reporting unit; the alarm unit sets the optical power operating range in the monitoring unit, and issues an alarm when the acquired optical power exceeds the preset range, while monitoring the optical power and reporting the specific value in real time according to the CMIS protocol.

8. The optical power monitoring device for an EML chip according to claim 7, characterized in that, It includes a feedback adjustment unit; when the optical power acquired by the monitoring unit exceeds the preset range, the feedback adjustment unit adjusts the response voltage output by the monitoring unit and / or the drive current output by the laser drive unit so that the adjusted optical power is within the preset range; wherein the laser drive unit drives the EML chip.

9. The optical power monitoring device for an EML chip according to claim 7, characterized in that, The alarm unit includes a storage module; the storage module stores the optical power value acquired by the monitoring unit.

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