Reflective light monitoring device and method in optical link and optical module

Abstract

The application discloses a device and method for monitoring reflected light in an optical link and an optical module, and is used to solve the problem of how to accurately perceive the reflected light signal in the optical link. The device comprises a first detector, which is coupled with the light signal reflected from the outgoing light signal of the optical transmitter to the optical link. The first detector is used to determine the first detection signal in the optical link. The first detection signal is used to reflect the light signal intensity reflected to the optical link and the background signal intensity in the optical chip. A second detector is arranged adjacent to the first detector and is not coupled with the light signal reflected from the outgoing light signal of the optical transmitter to the optical link. The second detector is used to determine the second detection signal in the optical link. The second detection signal is used to reflect the background signal intensity in the optical chip. An acquisition module is used to determine the reflected light intensity in the optical link based on the first detection signal and the second detection signal.

Description

Technical Field

[0001] This application belongs to the field of optical communication technology, specifically relating to a device and method for monitoring reflected light in an optical link, as well as an optical module. Background Technology

[0002] Ultra-compact optoelectronic devices and chips made with silicon photonics technology have become the mainstream solution for realizing large-scale, high-density optical interconnects. In these devices and chips, the high refractive index difference between silicon and the cladding and the complex mode conversion introduce a large number of parasitic reflections in the optical link. In order to protect the light source, diagnose link faults and optimize system performance, it is necessary to accurately sense the reflected light signals.

[0003] The information disclosed in this background section is intended only to enhance the understanding of the overall background of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0004] The purpose of this application is to provide a device for monitoring reflected light in an optical link, which solves the problem of how to accurately sense reflected light signals in an optical link.

[0005] To achieve the above objectives, this application provides a device for monitoring reflected light in an optical link, comprising:

[0006] The first detector is coupled to the optical signal reflected from the emitted optical signal at the optical transmitter to the optical link. The first detector is used to determine a first detection signal in the optical link. The first detection signal is used to reflect the intensity of the optical signal reflected to the optical link and the intensity of the background signal in the optical chip.

[0007] The second detector is disposed adjacent to the first detector and is not coupled to the optical signal reflected from the emitted optical signal of the optical emitter to the optical link. The second detector is used to determine the second detection signal in the optical link. The second detection signal is used to reflect the background signal intensity in the optical chip.

[0008] The acquisition module is used to determine the intensity of reflected light in the optical link based on the first detection signal and the second detection signal.

[0009] In one embodiment, the acquisition module is used to acquire the first detection signal and the second detection signal respectively, and determine the intensity of reflected light in the optical link based on the difference between the first detection signal and the second detection signal.

[0010] In one embodiment, the first detector and the second detector are connected in parallel.

[0011] In one embodiment, the acquisition module is used to acquire the difference between the first detection signal and the second detection signal to determine the intensity of reflected light in the optical link.

[0012] In one embodiment, the first detector and the second detector are connected in series, and the acquisition module is connected to the output node between the first detector and the second detector.

[0013] This application also provides another device for monitoring reflected light in an optical link, including:

[0014] A beam splitter is used to split the optical signal reflected from the optical transmitter to the optical link into a first optical signal and a second optical signal.

[0015] A phase modulator is used to modulate the phase of the second optical signal;

[0016] A beam combiner is used to combine the first optical signal and the phase-modulated second optical signal into a third optical signal;

[0017] A third detector is coupled to the third optical signal to determine a third detection signal, wherein the third detection signal is used to reflect the intensity of the optical signal reflected to the optical link and the intensity of the background signal in the optical chip;

[0018] A filter is used to filter the third detection signal to remove the DC component of the fourth detection signal, wherein the fourth detection signal is used to reflect the intensity of the partial optical signal reflected to the optical link and the intensity of the background signal in the optical chip.

[0019] In one embodiment, the beam splitter is used to proportionally split the optical signal reflected to the optical link into the first optical signal and the second optical signal; and / or,

[0020] The phase modulator includes a phase shifter based on radio frequency drive source modulation; and / or,

[0021] Both the beam splitter and the beam combiner include a multimode interferometer.

[0022] This application also provides a method for monitoring reflected light in an optical link, the method comprising:

[0023] A first detection signal in the optical link is determined, wherein the first detection signal is used to reflect the intensity of the optical signal reflected from the emitted optical signal at the optical transmitter to the optical link, and the intensity of the background signal in the optical chip;

[0024] A second detection signal in the optical link is determined, wherein the second detection signal is used to reflect the background signal intensity in the optical chip;

[0025] The intensity of reflected light in the optical link is determined based on the first detection signal and the second detection signal.

[0026] In one embodiment, the method specifically includes:

[0027] The first detection signal is determined based on the first detector, wherein the first detector is coupled to the optical signal reflected to the optical link;

[0028] The second detection signal is determined based on the second detector, wherein the second detector is not coupled to the optical signal reflected to the optical link, and the second detector is arranged adjacent to the first detector to receive the same background signal in the optical link;

[0029] The intensity of reflected light in the optical link is determined based on the difference between the first detection signal and the second detection signal.

[0030] In one embodiment, the method further includes: acquiring the first detection signal and the second detection signal respectively based on the acquisition module, so as to determine the difference between the first detection signal and the second detection signal.

[0031] In one embodiment, the first detector and the second detector are connected in parallel.

[0032] In one embodiment, the method further includes: acquiring the difference between the first detection signal and the second detection signal based on the acquisition module.

[0033] In one embodiment, the first detector and the second detector are connected in series, and the acquisition module is connected to the output node between the first detector and the second detector.

[0034] This application also provides another method for monitoring reflected light in an optical link, the method comprising:

[0035] A third detection signal in the optical link is determined, wherein the third detection signal is used to reflect the intensity of the optical signal reflected from the emitted optical signal at the optical transmitter to the optical link, and the intensity of the background signal in the optical chip;

[0036] A fourth detection signal in the optical link is determined, wherein the fourth detection signal is used to reflect the intensity of a portion of the optical signal reflected from the emitted optical signal at the optical transmitter to the optical link, and the intensity of the background signal in the optical chip;

[0037] The intensity of reflected light in the optical link is determined based on the third detection signal and the fourth detection signal.

[0038] In one embodiment, the method specifically includes:

[0039] The optical signal reflected to the optical link is split into a first optical signal and a second optical signal;

[0040] The second optical signal is phase-modulated, and the first optical signal and the phase-modulated second optical signal are combined into a third optical signal;

[0041] The third optical signal is coupled into the third detector to determine the third detection signal;

[0042] The third detection signal is filtered to remove the DC component of the fourth detection signal, thereby determining the intensity of reflected light in the optical link.

[0043] In one embodiment, the method specifically includes:

[0044] The optical signal reflected to the optical link is proportionally split into the first optical signal and the second optical signal using a beam splitter; and / or...

[0045] The second optical signal is phase-modulated by a phase shifter based on radio frequency driving source modulation.

[0046] This application also provides an optical module, including the reflected light monitoring device in the optical link as described above.

[0047] In one embodiment, the optical module includes at least two optical transmitters and at least two corresponding optical link reflection monitoring devices, wherein the at least two optical link reflection monitoring devices share the same acquisition module.

[0048] Compared with the prior art, the optical link reflection monitoring method and apparatus according to this application determines a first detection signal and a second detection signal in the optical link. The first detection signal reflects the intensity of the light signal reflected from the emitted light signal at the optical transmitter to the optical link and the intensity of the background signal in the optical chip. The second detection signal reflects the intensity of the background signal in the optical chip. Thus, the intensity of reflected light in the optical link can be determined based on the difference between the first detection signal and the second detection signal. Such a reflection light monitoring method can eliminate the influence of the background signal, optimize the signal-to-noise ratio, and improve the accuracy of reflection light monitoring.

[0049] On the other hand, the background signal can be eliminated directly in the analog domain by directly acquiring the difference between the first and second detection signals, which reduces the number of acquisition channels and subsequent computational overhead, while avoiding the errors that may be introduced during separate acquisition and quantization, thereby further optimizing the signal-to-noise ratio and improving the accuracy of reflected light monitoring.

[0050] According to the optical link reflection monitoring method and apparatus of this application, a third detection signal and a fourth detection signal in the optical link can be determined. The third detection signal is used to reflect the intensity of the optical signal reflected from the output optical signal of the optical transmitter to the optical link and the intensity of the background signal in the optical chip. The fourth detection signal is used to reflect the intensity of part of the optical signal reflected from the output optical signal of the optical transmitter to the optical link and the intensity of the background signal in the optical chip. Thus, the intensity of reflected light in the optical link can be determined based on the difference between the third detection signal and the fourth detection signal. Such a reflection light monitoring method can also eliminate the influence of the background signal, optimize the signal-to-noise ratio, and improve the accuracy of reflection light monitoring.

[0051] On the other hand, the third and fourth detection signals do not necessarily need to be detected by separate detectors. Instead, the third detection signal can be determined by a single detector, and the fourth detection signal can be directly filtered out through subsequent filtering, thereby reducing the number of detectors required and lowering manufacturing costs. Attached Figure Description

[0052] Figure 1 This is a flowchart of a method for monitoring reflected light in an optical link according to an embodiment of this application;

[0053] Figure 2 This is a schematic block diagram of the reflected light monitoring device in the optical link according to the first embodiment of this application;

[0054] Figure 3 This is a schematic block diagram of a reflected light monitoring device in an optical link according to the second embodiment of this application;

[0055] Figure 4 This is a flowchart of a method for monitoring reflected light in an optical link according to another embodiment of this application;

[0056] Figure 5 This is a schematic block diagram of a reflected light monitoring device in an optical link according to the third embodiment of this application;

[0057] Figure 6 It is an application Figure 2 The schematic diagram of the optical module of the reflected light monitoring device is shown.

[0058] Figure 7 It is an application Figure 3 The schematic diagram of the optical module of the reflected light monitoring device is shown.

[0059] Figure 8 It is an application Figure 5 The schematic diagram of the optical module of the reflected light monitoring device is shown.

[0060] Figure 9 This is a hardware structure diagram of an electronic device according to an embodiment of this application.

[0061] Explanation of key figure labels:

[0062] 10, 10a, 10b - Reflected light monitoring device; 11, 11a - First detector; 11b - Third detector; 12, 12a - Second detector; 13, 13a, 13b - Acquisition module; 14b - Beam splitter; 15b - Beam combiner; 16b - Phase shifter; 17b - Radio frequency driver.

[0063] 20-Input Port;

[0064] 30-Electro-optic modulator;

[0065] 40- Spectrometer;

[0066] 50 - Output port;

[0067] 60 - Target device. Detailed Implementation

[0068] The present application will now be described in detail with reference to the embodiments shown in the accompanying drawings. However, these embodiments do not limit the present application, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the protection scope of the present application.

[0069] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “corresponding to,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0070] To monitor the reflected optical signal of an optoelectronic device or an optical chip, a light splitting device may be used to couple the backward-propagating optical signal to an on-chip photodetector (PD), which is an optional embodiment. However, scattering caused by sidewall roughness of intra-chip waveguides, optical leakage from edge couplers to the substrate, and radiation loss of various devices will form a background stray light field with complex spatial distribution in the cladding and the substrate. These background stray lights are collected indiscriminately by the photodetector, and the intensity of the reflected signal transmitted in the waveguide is usually lower than -25dBm, so the photocurrents generated by the two may overlap. In addition, existing silicon photonic on-chip photodetectors are generally based on heterogeneous integrated germanium processes. Limited by the narrow bandgap of germanium materials, the intrinsic carrier concentration increases sharply at high temperatures, and the dark current increases exponentially accompanied by significant random fluctuations. This dark current component may also overlap with the photocurrent of the reflected signal. These factors together lead to a decrease in the sensitivity of reflected light detection, making the reflected light monitoring system unable to accurately identify and quantify the reflected light power.

[0071] Based on the consideration of the above problems, one aspect of the overall idea of the present application is proposed: two different detection signals are determined in the optical link, one detection signal is used to reflect the intensity of the optical signal reflected from the output optical signal of the light emitting end to the optical link and the background signal intensity in the optical chip, and the other detection signal is used to reflect the background signal intensity in the optical chip. In this way, based on the difference comparison between the two detection signals, the intensity of the optical signal reflected to the optical link can be distinguished therefrom, and the influence of the background signal in the optical link can be eliminated.

[0072] Another aspect of the overall idea of the present application is that two different detection signals are also determined in the optical link, one detection signal is used to reflect the intensity of the optical signal reflected from the output optical signal of the light emitting end to the optical link and the background signal intensity in the optical chip, and the other detection signal is used to reflect the intensity of a part of the optical signal reflected from the output optical signal of the light emitting end to the optical link and the background signal intensity in the optical chip. In this way, based on the difference comparison between the two detection signals, the intensity of the optical signal reflected to the optical link can also be distinguished therefrom, and the influence of the background signal in the optical chip can be eliminated.

[0073] It should be noted that the "background signal intensity" mentioned in the present application may correspond to signals from different sources in different embodiments. Generally, it can be any other signal except the optical signal reflected to the optical link. For example, the "background signal intensity" may include the signal intensity corresponding to the aforementioned background stray light, and this part of the background signal can be captured by a detector in the form of an optical signal and converted into a current signal. For another example, when an on-chip integrated photodetector is used, the "background signal intensity" may also include the signal intensity corresponding to the aforementioned dark current, which is not limited in the present application.

[0074] Reference Figure 1 and Figure 2 This paper introduces a specific embodiment of a method for monitoring reflected light in an optical link based on the above overall approach.

[0075] Figure 2 This illustration shows an optical chip architecture for applying the reflected light monitoring method in the optical link of this embodiment, with the transmitter portion primarily relevant to the scheme of this embodiment shown. Figure 2 As shown, the optical signal generated by the light source is coupled into the optical waveguide through the input port 20, modulated by the electro-optic modulator 30 (MZM or micro-ring modulator), and then coupled to the output port 50 through the beam splitter 40. A typical beam splitter 40 is, for example, a directional coupler (DC), whose splitting ratio can be designed according to the actual application requirements. In addition to the portion coupled to the output port, the beam splitter 40 can also couple a portion of the optical signal into other target devices 60 to achieve different functions. For example, the target device 60 can be a ring waveguide, a photodetector, etc., to monitor the wavelength and power of the emitted optical signal, or to directly dissipate this portion of the emitted optical signal. After the emitted optical signal from the optical transmitter is reflected back into the optical link, it passes through the beam splitter 40 again and is at least partially coupled to the reflected light monitoring device 10, which then monitors the reflected light in the optical link.

[0076] Specifically, in this embodiment, the method for monitoring reflected light in the optical link includes the steps shown below.

[0077] S11. Determine the first detection signal in the optical link.

[0078] The first detection signal is used to reflect the intensity of the optical signal reflected from the optical transmitter to the optical link, as well as the intensity of the background signal in the optical chip. Specifically, the first detection signal can be determined based on the first detector 11. The first detector 11 can be coupled with the optical signal reflected to the optical link, that is, the first detector 11 simultaneously receives part of the optical signal that enters the optical link after reflection from the optical transmitter, as well as the inherent background signal in the optical chip, and converts and superimposes the two into an electrical signal, which is used as the first detection signal.

[0079] For example, the first detector 11 can be a photodetector (PD), a PIN photodiode, an avalanche photodiode (APD), a metal-semiconductor-metal (MSM) photodetector, etc., and this application does not limit it. The first detector 11 can be disposed at the port of the directional coupler (corresponding to reference numeral 40) of the main waveguide after the optical transmitter electro-optic modulator 30, and generate a current signal (i.e., the first detection signal):

[0080]

[0081] in, This represents the current component generated by the reflected light signal. This represents the current component generated by the background signal.

[0082] S12. Determine the second detection signal in the optical link.

[0083] The second detection signal is used to reflect the background signal intensity in the optical chip. Specifically, the second detection signal can be determined based on the second detector 12. The second detector 12 is not coupled to the optical signal reflected to the optical link, and the second detector 12 is arranged adjacent to the first detector 11 to receive the same background signal in the optical link. Compared to the first detector 11, the second detector 12 only receives the background signal in the optical chip and does not receive the optical signal reflected back to the optical link after being emitted from the optical emitter. The second detector 12 can directly receive the background signal in the form of "dark current," or it can convert the background signal in the form of "stray light" into a corresponding current signal. The second detection signal is expressed as follows:

[0084]

[0085] Since the spatial non-uniformity of the on-chip stray light field is much smaller than the light-receiving size of the detector, the stray light field can be approximated as uniformly distributed within a sufficiently close local area. Therefore, when the first detector 11 and the second detector 12 are spatially close, the stray light intensities received by them can be considered approximately equal. Taking the typical size of an optical chip as an example, stray light across the entire chip scale can generally be considered approximately uniformly distributed. Therefore, the first detector 11 and the second detector 12 can be placed at any suitable location on the optical chip according to design requirements. Of course, in some alternative embodiments, the first detector 11 and the second detector 12 may not both be placed on the same optical chip. In such embodiments, those skilled in the art can also select adjacent locations with approximately equal background signals in a reasonable manner and place the detectors as described above. This application does not impose numerical limitations on the specific spatial relationship between the two detectors.

[0086] S13. Determine the intensity of reflected light in the optical link based on the first detection signal and the second detection signal.

[0087] Specifically, since the first detection signal reflects the signal intensity of the reflected light signal and the background signal, and the second detection signal reflects the background signal intensity, the reflected light intensity in the optical link can be determined based on the difference between the first and second detection signals. That is, the influence of the background signal can be eliminated by directly subtracting the second detection signal from the first detection signal, thus obtaining a signal related to the reflected light intensity, and thereby determining the reflected light intensity in the optical link.

[0088] In this way, this embodiment can accurately distinguish between reflected light signals and background signals when the emitted light signal at the optical transmitter is reflected, thereby enabling the monitoring of reflected light in the optical link, avoiding interference from background signals on the monitoring results of reflected light, thus optimizing the signal-to-noise ratio and improving the accuracy of reflected light monitoring.

[0089] Continue to cooperate with the participants Figure 2 In this embodiment, the method may further include: acquiring the first detection signal and the second detection signal respectively based on the acquisition module 13. Exemplarily, the acquisition module 13 may include a transimpedance amplifier (TIA), an analog-to-digital converter (ADC), etc., wherein the current signals output by the first detector 11 and the second detector 12 can be first converted into voltage signals by the transimpedance amplifier and amplified, and then converted into digital signals by the analog-to-digital converter for subsequent difference calculations. It is understood that the specific circuit configuration of the acquisition module 13 can be set according to actual application requirements, and this application does not limit it in this regard.

[0090] In this embodiment, the first detector 11 and the second detector 12 are connected in parallel. Exemplarily, the first terminal of the first detector 11 and the first terminal of the second detector 12 are both electrically connected to the same high-potential node, and the second terminals of the first detector 11 and the second detector 12 are both electrically connected to the same low-potential node, so that both operate under the same bias voltage. For example, the high-potential node is connected to 1.5V, and the low-potential node is grounded. This ensures that the two detectors operate under essentially the same environment, thereby reducing errors introduced by factors such as device differences and temperature drift, and further improving the accuracy of reflected light monitoring.

[0091] Coordination Figure 3 As with Figure 2 In another embodiment parallel to the illustrated embodiment, the acquisition module 13a directly acquires the difference between the first detection signal and the second detection signal. Specifically, the first detector 11a and the second detector 12a are connected in series, and the acquisition module 13a is connected to the output node between the first detector 11a and the second detector 12a, forming a circuit similar to a differential design.

[0092] For example, a common bias voltage of 3V is connected to both ends of the series branch of the first detector 11a and the second detector 12a, for example, the high-potential node is connected to 3V and the low-potential node is grounded. The output node between the first detector 11a and the second detector 12a can be clamped to half of the series branch bias voltage, i.e., 1.5V, so that both detectors operate under the same bias conditions.

[0093] In this embodiment, the first detector 11a is also coupled with the optical signal reflected to the optical link, and the second detector 12a is not coupled with the optical signal reflected to the optical link. The difference between the current signal generated by the first detector 11a and the current signal generated by the second detector 12a reflects the intensity of the optical signal reflected to the optical link. The photocurrent collected by the acquisition circuit at the output node has directly eliminated the influence of the background signal, which can be expressed as:

[0094]

[0095] That is, this embodiment does not need to separately collect the first detection signal and the second detection signal and then perform difference calculation. Instead, the acquisition module 13a directly collects the difference signal at the output node. Compared with the method of collecting the first detection signal and the second detection signal separately and then performing difference calculation, this embodiment can directly complete the elimination of the background signal in the analog domain, reduce the number of acquisition channels and subsequent calculation overhead, and avoid errors that may be introduced in the separate acquisition and quantization process, thereby further optimizing the signal-to-noise ratio and improving the accuracy of reflected light monitoring. In terms of structure, this concise on-chip differential architecture enables reflection monitoring to have high immunity to background signals, and is particularly suitable for high-speed optical interconnection scenarios with stringent requirements for link integrity.

[0096] Referring to Figure 2 and Figure 3 , the first detector and the second detector therein can be simultaneously manufactured in the same standard silicon photonic process, without additional end face processing or external isolators, maintaining high integration and low manufacturing cost. For comparison, assume that the number of channels of the optical chip is X. Figure 2 In the embodiment shown in, the acquisition module 13 requires two acquisition channels, corresponding to two electrode PADs, and the high potential node externally connected to the circuit corresponds to one electrode PAD (shared by each channel), so the total number of electrode PADs is 2X+1. Figure 3 In the embodiment shown in, the acquisition module 13a only requires one acquisition channel, corresponding to one electrode PAD, and the high potential node and low potential node externally connected to the circuit correspond to two electrode PADs (shared by each channel), so the total number of electrode PADs is X+2. It can be seen that Figure 3 the embodiment shown in compared to the embodiment shown in Figure 2 the embodiment shown in can save nearly half of PAD resources, and shows more structural design advantages in optical chips with a high number of channels.

[0097] Referring to Figure 4 and Figure 5 , another specific embodiment of the reflected light monitoring method in an optical link based on the above general idea is introduced.

[0098] Figure 5This illustrates an optical chip architecture to which the reflected light monitoring method in the optical link of this embodiment can be applied. For example... Figure 5 As shown, in this optical chip architecture, except for the reflected light monitoring device 10b, the structure of the remaining parts is similar to... Figure 3 and Figure 4 The illustrated embodiments are similar and will not be described again here.

[0099] Specifically, in this embodiment, the method for monitoring reflected light in the optical link includes the steps shown below.

[0100] S21. Determine the third detection signal in the optical link.

[0101] S22. Determine the fourth detection signal in the optical link.

[0102] S23. Based on the third and fourth detection signals, determine the intensity of reflected light in the optical link.

[0103] The third detection signal is used to reflect the intensity of the optical signal reflected from the optical transmitter to the optical link, as well as the intensity of the background signal in the optical chip. Specifically, the optical signal reflected to the optical link can be split into a first optical signal and a second optical signal, and the second optical signal can be phase-modulated. The phase-modulated second optical signal and the first optical signal are combined to form a third optical signal, which is then coupled into the third detector 11b. Since the third optical signal is obtained by combining the first optical signal and the phase-modulated second optical signal, the third detection signal determined by the third detector 11b can simultaneously reflect the intensity of the optical signal reflected to the optical link and the intensity of the background signal in the optical chip.

[0104] Similarly, the third detector 11b can be a photodetector (PD), a PIN photodiode, an avalanche photodiode (APD), a metal-semiconductor-metal (MSM) photodetector, etc., and this application does not limit it.

[0105] Specifically, in this embodiment, the optical signal reflected to the optical link can be proportionally split into a first optical signal and a second optical signal based on the beam splitter 14b. Subsequently, the second optical signal is phase-modulated based on the phase shifter 16b modulated by the RF driver 17b.

[0106] Under these conditions, the unmodulated first optical signal can be represented as:

[0107]

[0108] in, This represents the initial amplitude of the optical signal reflected to the optical link; the first optical signal. It contains half of the reflected light signal and half of the background signal in the chip. and These are the angular frequency and initial phase of the optical signal reflected into the optical link, respectively.

[0109] The modulated second optical signal can be represented as:

[0110]

[0111] in, and These represent the angular frequency and initial phase of the modulated radio frequency signal, respectively. This is the phase modulation index of the phase shifter.

[0112] The third optical signal obtained after combining the first and second optical signals can be represented as:

[0113]

[0114] Assuming the responsivity of the third detector 11b is R, the current signal (i.e., the third detection signal) output by it in response to the third optical signal can be expressed as:

[0115]

[0116] The fourth detection signal is used to reflect the intensity of the portion of the optical signal reflected from the optical transmitter to the optical link, as well as the background signal intensity in the optical chip. Specifically, the detection sources of the third detection signal include phase-modulated optical signals and unmodulated optical signals, which, when reflected in the third detection signal, will generate AC and DC components. The DC component reflects the intensity of the portion of the optical signal reflected to the optical link and the background signal intensity in the optical chip, which is the fourth detection signal that this embodiment aims to determine.

[0117] In this embodiment, the third detection signal can be filtered using a filter (not shown) to remove the DC component of the fourth detection signal, thereby determining the intensity of reflected light in the optical link. Simultaneously, since the filtered fourth detection signal also reflects the intensity of a portion of the optical signal reflected to the optical link, the intensity of the filtered portion of reflected light signal needs to be considered when determining the intensity of reflected light in the optical link based on the AC component of the third detection signal. For example, the intensity of this filtered portion of reflected light signal can be determined by the beam splitting ratio of the first and second optical signals. Specific methods for determining signal intensity can be selected according to actual design needs, and this application will not elaborate on them.

[0118] For example, the filter can be a high-pass filter or a band-pass filter. Since the AC component in the third detection signal is mainly concentrated at the frequency modulated by the RF driver 17b, while the DC component (the fourth detection signal) is located near zero frequency, the DC component and AC component can be effectively separated by setting an appropriate filter cutoff frequency. For example, the frequency of the RF driver 17b can be set to 100MHz, which is higher than the zero frequency where the DC component is located, so that a high-pass filter can be easily used to filter out the DC component and retain the AC component related to the intensity of the reflected light.

[0119] This embodiment converts the optical signal reflected to the optical link from the optical domain to the radio frequency domain using the method described above. Background signals (background stray light, dark current, etc.) are considered to contribute only a DC component due to their incoherence or relatively weak signal strength. Therefore, only filtering of the third detection signal is needed to completely remove the background signal (DC component) in the electrical domain, thereby accurately distinguishing the reflected light signal from the background signal and achieving monitoring of reflected light in the optical link. Furthermore, with... Figure 2 , Figure 3 Compared to the embodiment that requires two detectors (first and second detectors), this embodiment only requires one third detector 11b to monitor reflected light in the optical link, making it more economical.

[0120] Continue to cooperate with reference Figure 5 In this embodiment, the optical signal reflected to the optical link can be proportionally split based on the beam splitter 14b. For example, the beam splitter 14b may include a multimode interferometer (MMI), which can proportionally split the incident optical signal into a first optical signal and a second optical signal, i.e., a splitting ratio of 50:50. By proportionally splitting the beam, the first optical signal and the second optical signal can be guaranteed to have the same optical power, thereby obtaining optimal interference contrast during beam combining, maximizing the amplitude of the AC component, and further improving the sensitivity of reflected light monitoring.

[0121] In this embodiment, the phase modulation of the second optical signal can be achieved based on the phase shifter 16b modulated by the radio frequency drive source 17b. For example, the phase shifter 16b can be a phase shifter based on the thermo-optic effect or the electro-optic effect. The phase shifter 16b is modulated by a sinusoidal drive signal with a frequency of 1000 Hz output by the radio frequency drive source 17b, so that the second optical signal obtains phase modulation.

[0122] In this embodiment, the first optical signal and the phase-modulated second optical signal can be combined into a third optical signal based on the beam combiner 15b. Exemplarily, the beam combiner 15b may also include a multimode interferometer, thus employing the same fabrication structure as the beam splitter 14b, facilitating on-chip integration and reducing design and fabrication complexity. It is understood that the beam splitter 14b and beam combiner 15b may also employ other beam splitting / combining structures such as directional couplers (DC) and Y-branch waveguides; this application does not impose any limitations on this.

[0123] Continue to participate Figure 2 This application also provides a device 10 for monitoring reflected light in an optical link. In combination with the above... Figure 1 and Figure 2 The details mentioned in the description of the method embodiments may be applied in part or in whole to the following apparatus embodiments.

[0124] In this embodiment, the optical link reflected light monitoring device 10 includes a first detector 11, a second detector 12, and a data acquisition module 13.

[0125] The first detector 11 is coupled to the optical signal reflected from the emitted optical signal at the optical transmitter to the optical link, and is used to determine the first detection signal in the optical link. The first detection signal reflects the intensity of the optical signal reflected to the optical link and the background signal intensity in the optical chip. Specifically, the first detector 11 can be located at the port of the beam splitter 40 (e.g., a directional coupler DC) of the main waveguide after the electro-optic modulator 30 at the transmitter, to receive the reflected optical signal that re-enters the main waveguide and convert it into a corresponding electrical signal. Exemplarily, the first detector 11 can be a photodetector (PD), a PIN photodiode, an avalanche photodiode (APD), a metal-semiconductor-metal (MSM) photodetector, etc., and this application does not impose any limitations on this.

[0126] The second detector 12 is not coupled to the optical signal reflected from the emitted optical signal at the optical transmitter to the optical link. It is used to determine a second detection signal in the optical link, wherein the second detection signal reflects the background signal intensity in the optical chip. Specifically, the second detector 12 can be located near the first detector 11 but not coupled to the reflected optical signal. For example, it can be located outside the main waveguide and in an area exposed only to the background stray light field, thereby receiving only the background signal (such as background stray light, dark current) in the optical chip and not receiving the optical signal reflected back to the optical link. Exemplarily, the type of the second detector 12 can be the same as or similar to the first detector 11, and this application does not limit this.

[0127] The acquisition module 13 is used to determine the intensity of reflected light in the optical link based on the first detection signal and the second detection signal. Exemplarily, the acquisition module 13 may include a transimpedance amplifier (TIA), an analog-to-digital converter (ADC), etc. The current signals output by the first detector 11 and the second detector 12 can be first converted into voltage signals by the transimpedance amplifier and amplified, and then converted into digital signals by the analog-to-digital converter for subsequent calculations. It is understood that the specific circuit configuration of the acquisition module 13 can be set according to actual application requirements, and this application does not limit it in this regard.

[0128] Continue to cooperate with reference Figure 2 In this embodiment, the acquisition module 13 is used to acquire the first detection signal and the second detection signal respectively, and determine the intensity of reflected light in the optical link based on the difference between the first detection signal and the second detection signal. Figure 2 As can be seen, the first detector 11 and the second detector 12 are connected in parallel. The first terminal of the first detector 11 and the first terminal of the second detector 12 are both electrically connected to the same high-potential node, and the second terminal of the first detector 11 and the second terminal of the second detector 12 are both electrically connected to the same low-potential node, so that they operate under the same bias voltage. For example, the high-potential node is connected to 1.5V, and the low-potential node is grounded. In this way, the two detectors are ensured to be in a basically consistent operating environment, thereby reducing the errors introduced by factors such as device differences and temperature drift, and further improving the accuracy of reflected light monitoring.

[0129] Continue to refer to Figure 3 This paper introduces another embodiment of the optical link reflection monitoring device 10a provided in this application. Similarly, in conjunction with the above... Figure 1 and Figure 3 The details mentioned in the description of the method embodiments may be applied in part or in whole to the following apparatus embodiments.

[0130] and Figure 2Unlike the illustrated embodiment, in this embodiment, the acquisition module 13a is used to acquire the difference between the first detection signal and the second detection signal to determine the intensity of reflected light in the optical link. Specifically, the first detector 11a and the second detector 12a are connected in series, and the acquisition module 13a is connected to the output node between the first detector 11a and the second detector 12a, forming a circuit similar to a differential design. For example, a common 3V bias voltage is connected to both ends of the series branch of the first detector 11a and the second detector 12a, for example, the high-potential node is connected to 3V and the low-potential node is grounded; the output node between the first detector 11a and the second detector 12a can be clamped to half the bias voltage of the series branch, i.e., 1.5V, so that both detectors operate under the same bias conditions. At this time, the photocurrent acquired by the acquisition module 13a at the output node has directly eliminated the influence of the background signal, that is, there is no need to separately acquire the first and second detection signals and then perform difference calculations, but the background signal elimination is directly completed in the analog domain, thereby reducing the number of acquisition channels and subsequent computational overhead, while avoiding errors that may be introduced during separate acquisition and quantization processes.

[0131] Continue to refer to Figure 5 This paper introduces another embodiment of the optical link reflection monitoring device 10b provided in this application. Similarly, in conjunction with the above... Figure 4 and Figure 5 The details mentioned in the description of the method embodiments may be applied in part or in whole to the following apparatus embodiments.

[0132] like Figure 5 As shown, in this embodiment, the reflected light monitoring device 10b in the optical link includes a beam splitter 14b, a phase modulator, a beam combiner 15b, a third detector 11b, and a filter (not shown).

[0133] Beam splitter 14b is used to split the optical signal reflected from the optical transmitter to the optical link into a first optical signal and a second optical signal. Exemplarily, beam splitter 14b may include a multimode interferometer (MMI), which can split the incident optical signal into a first optical signal and a second optical signal proportionally, i.e., a splitting ratio of 50:50. By splitting the beam proportionally, the first optical signal and the second optical signal can be guaranteed to have the same optical power, thereby obtaining optimal interference contrast during beam combining, maximizing the amplitude of the AC component, and further improving the sensitivity of reflected light monitoring. It is understood that beam splitter 14b may also employ other beam splitting structures such as a directional coupler (DC), a Y-branch waveguide, etc., and this application does not limit this.

[0134] A phase modulator is used to modulate the phase of a second optical signal. Exemplarily, the phase modulator includes a phase shifter 16b modulated based on a radio frequency drive source 17b. The phase shifter 16b can be a phase shifter based on a thermo-optic effect or an electro-optic effect, such as a phase shifter based on silicon-based carrier dispersion effect, the electro-optic effect of lithium niobate crystals, etc., and this application does not limit this.

[0135] Beam combiner 15b is used to combine the first optical signal and the phase-modulated second optical signal into a third optical signal. Exemplarily, beam combiner 15b may also include a multimode interferometer (MMI), thus employing the same fabrication process as beam splitter 14b, facilitating on-chip integration and reducing design and fabrication complexity. It is understood that beam combiner 15b may also employ other beam combining structures such as directional couplers (DC) or Y-branch waveguides; this application does not impose any limitations on this.

[0136] The third detector 11b is coupled to a third optical signal to determine a third detection signal, which reflects the intensity of the optical signal reflected to the optical link and the intensity of the background signal in the optical chip. Exemplarily, the third detector 11b can be a photodetector (PD), a PIN photodiode, an avalanche photodiode (APD), a metal-semiconductor-metal (MSM) photodetector, etc., and this application is not limited thereto. The third detection signal determined by the third detector 11b can be acquired by the shown acquisition module 13b and fed into a filter.

[0137] A filter is used to filter the third detection signal to remove the DC component of the fourth detection signal, which reflects the intensity of the optical signal reflected to the optical link and the background signal intensity in the optical chip. For example, the filter can be a high-pass filter or a band-pass filter. Since the AC component in the third detection signal is mainly concentrated at the frequency of the RF driver, while the DC component (the fourth detection signal) is located near zero frequency, the DC and AC components can be effectively separated by setting an appropriate filter cutoff frequency.

[0138] It is understandable that the aforementioned acquisition module 13b, beam splitter 14b, phase modulator, beam combiner 15b, third detector 11b, and filter can be integrated onto the same optical chip, and optical and electrical interconnects can be achieved through waveguides and metal wiring, respectively, thus forming an on-chip integrated reflected light monitoring device 10b. This further reduces the device size and improves integration, making it suitable for large-scale, high-density optical interconnect scenarios. Taking a silicon-based platform as an example, the chip area can be controlled within 0.5 mm². 2Alternatively, these devices can be assembled from independent optical components, for example, interconnected through packaging: optical connections can be achieved via optical fibers or spatial optical paths (such as lenses, free-space propagation, etc.), while electrical connections can be completed using methods such as wire bonding and flip-chip bonding. Compared to on-chip integration, this approach is relatively large, typically several millimeters in size. 2 Up to tens of millimeters 2 However, each device is independent of the others, which facilitates separate verification and flexible configuration.

[0139] Regarding the implementation platform, the optical link reflection monitoring device 10b shown in the above embodiments can be implemented based on a variety of material platforms, such as Si, SiN, SiON, SiO2, SiC, InP, GaAs, GaN, LiNbO3, BaTiO3, etc., and this application does not limit it.

[0140] Coordination Figures 6 to 8 This application describes embodiments of the optical module provided. In these embodiments, the optical module may include the reflected light monitoring device in the optical link described above.

[0141] like Figure 6 As shown, the optical module includes two optical transmitters (DR2) and two corresponding optical link reflection monitoring devices 10, and these two optical link reflection monitoring devices 10 share the same acquisition module 13. It can be seen that... Figure 6 In the illustrated embodiment, the method used is Figure 2 The reflected light monitoring device shown in the embodiment.

[0142] like Figure 7 As shown, the optical module includes four optical transmitters (DR4) and corresponding four optical link reflection monitoring devices 10a, and... Figure 6 Unlike the illustrated embodiment, in this embodiment, the four reflected light monitoring devices 10a do not share a common acquisition module; instead, each device has its own corresponding acquisition module 13a for signal acquisition. It can be seen that... Figure 7 In the illustrated embodiment, the method used is Figure 3 The reflected light monitoring device shown in the embodiment.

[0143] like Figure 8 As shown, the optical module includes four optical transmitters (DR4) and four corresponding optical link reflection monitoring devices 10b, and these four optical link reflection monitoring devices 10b share the same acquisition module 13a. It can be seen that... Figure 8 In the illustrated embodiment, the method used is Figure 5 The reflected light monitoring device shown in the embodiment.

[0144] It should be noted that each transmitter of the optical module mentioned in the embodiments of this application may correspond to the same light source and input port, and be divided into independent optical paths by a beam splitter within the optical module. The optical signals of these optical paths can be modulated by devices such as MZM modulators to generate the desired optical signal.

[0145] Taking the DR4 optical module application shown as an example, assuming the operating wavelength of the DR4 optical module is 1310nm, the output optical power is 0dBm to 5dBm, each of the four transmitters is equipped with an independent reflected light monitoring device, the dark current of the detector is less than 50nA, the responsivity is 1A / W, and the minimum detectable optical power reaches -43dBm. The splitting ratio of the beam splitter (DC) is set to 90:10, for example... Figure 5 The reflection monitoring device shown can have its reflected light intensity alarm threshold set to -39dBm, including the losses of the beam splitter (MMI), beam combiner 15b (MMI), and DC losses. For example... Figure 2 and Figure 3 The reflection monitoring unit shown can have its reflected light intensity alarm threshold set to -36dBm, including DC losses. Monitoring is performed every 3 minutes, 5 minutes, 8 minutes, and 10 minutes. When the detected reflected light intensity exceeds the threshold, it indicates a potential reflection problem in the optical link and triggers an alarm signal.

[0146] As per the above reference Figures 1 to 8 The method for monitoring reflected light in an optical link according to embodiments of this specification has been described. In another aspect, the above-described device for monitoring reflected light in an optical link can be implemented directly using the hardware shown, or it can be implemented using software or a combination of hardware and software.

[0147] Figure 9 A hardware structure diagram of an electronic device according to an embodiment of this specification is shown. Figure 9 As shown, the electronic device may include at least one processor, a memory (e.g., non-volatile memory), a RAM, and a communication interface, and the at least one processor, memory, RAM, and communication interface are connected together via an internal bus. At least one processor executes at least one computer-readable instruction stored or encoded in the memory.

[0148] It should be understood that the computer-executable instructions stored in memory, when executed, cause at least one processor to perform the above-described combinations in the various embodiments of this specification. Figures 1 to 8 Describe at least some of the operations and functions.

[0149] In the embodiments of this specification, electronic devices may include, but are not limited to: personal computers, server computers, workstations, desktop computers, laptop computers, notebook computers, mobile electronic devices, smartphones, tablet computers, cellular phones, personal digital assistants (PDAs), handheld devices, messaging devices, wearable electronic devices, consumer electronic devices, etc.

[0150] According to one embodiment, a program product, such as a machine-readable medium, is provided. The machine-readable medium may have instructions (i.e., the elements implemented in software as described above), which, when executed by a machine, cause the machine to perform the above-described combinations of the various embodiments of this specification. Figures 1-8 The various operations and functions described. Specifically, a system or apparatus equipped with a readable storage medium storing software program code that implements the functions of any of the embodiments described above, and enabling the computer or processor of the system or apparatus to read and execute the instructions stored in the readable storage medium.

[0151] In this case, the program code read from the readable medium itself can perform the functions of any of the above embodiments, and therefore the machine-readable code and the readable storage medium storing the machine-readable code constitute a part of this specification.

[0152] Examples of readable storage media include floppy disks, hard disks, magneto-optical disks, optical disks (such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD-RW), magnetic tapes, non-volatile memory cards, and ROMs. Alternatively, program code can be downloaded from a server computer or the cloud via a communication network.

[0153] Those skilled in the art will understand that the various embodiments disclosed above can be modified and varied without departing from the spirit of the invention. Therefore, the scope of protection of this specification should be defined by the appended claims.

[0154] It should be noted that not all steps and units in the above process and system structure diagrams are mandatory; some steps or units can be omitted according to actual needs. The execution order of each step is not fixed and can be determined as needed. The device structure described in the above embodiments can be a physical structure or a logical structure. That is, some units may be implemented by the same physical client, or some units may be implemented by multiple physical clients, or they may be jointly implemented by certain components in multiple independent devices.

[0155] In the above embodiments, the hardware units or modules can be implemented mechanically or electrically. For example, a hardware unit, module, or processor may include permanent dedicated circuitry or logic (such as a dedicated processor, FPGA, or ASIC) to perform the corresponding operation. The hardware unit or processor may also include programmable logic or circuitry (such as a general-purpose processor or other programmable processor), which can be temporarily configured by software to perform the corresponding operation. The specific implementation method (mechanical, dedicated permanent circuitry, or temporarily configured circuitry) can be determined based on cost and time considerations.

[0156] The specific embodiments described above with reference to the accompanying drawings are exemplary embodiments, but do not represent all embodiments that can be implemented or fall within the scope of the claims. The term "exemplary" as used throughout this specification means "serving as an example, instance, or illustration" and does not imply that it is "preferred" or "advantageous" compared to other embodiments. Specific details are included to provide an understanding of the described techniques. However, these techniques can be practiced without these specific details. In some instances, well-known structures and apparatuses are shown in block diagram form to avoid obscuring the concepts of the described embodiments.

[0157] The foregoing description of this disclosure is provided to enable any person skilled in the art to implement or use this disclosure. Various modifications to this disclosure will be apparent to those skilled in the art, and the general principles applicable herein can be applied to other variations without departing from the scope of this disclosure. Therefore, this disclosure is not limited to the examples and designs described herein, but is consistent with the widest scope of the principles and novel features disclosed herein.

Claims

1. A device for monitoring reflected light in an optical link, characterized in that, include: The first detector is coupled to the optical signal reflected from the emitted optical signal at the optical transmitter to the optical link. The first detector is used to determine a first detection signal in the optical link. The first detection signal is used to reflect the intensity of the optical signal reflected to the optical link and the intensity of the background signal in the optical chip. The second detector is disposed adjacent to the first detector and is not coupled to the optical signal reflected from the emitted optical signal of the optical emitter to the optical link. The second detector is used to determine the second detection signal in the optical link. The second detection signal is used to reflect the background signal intensity in the optical chip. The acquisition module is used to determine the intensity of reflected light in the optical link based on the first detection signal and the second detection signal.

2. The optical link reflected light monitoring device according to claim 1, characterized in that, The acquisition module is used to acquire the first detection signal and the second detection signal respectively, and determine the intensity of reflected light in the optical link based on the difference between the first detection signal and the second detection signal.

3. The optical link reflected light monitoring device according to claim 2, characterized in that, The first detector and the second detector are connected in parallel.

4. The optical link reflected light monitoring device according to claim 1, characterized in that, The acquisition module is used to acquire the difference between the first detection signal and the second detection signal to determine the intensity of reflected light in the optical link.

5. The optical link reflected light monitoring device according to claim 4, characterized in that, The first detector and the second detector are connected in series, and the acquisition module is connected to the output node between the first detector and the second detector.

6. A device for monitoring reflected light in an optical link, characterized in that, include: A beam splitter is used to split the optical signal reflected from the optical transmitter to the optical link into a first optical signal and a second optical signal. A phase modulator is used to modulate the phase of the second optical signal; A beam combiner is used to combine the first optical signal and the phase-modulated second optical signal into a third optical signal; A third detector is coupled to the third optical signal to determine a third detection signal, wherein the third detection signal is used to reflect the intensity of the optical signal reflected to the optical link and the intensity of the background signal in the optical chip; A filter is used to filter the third detection signal to remove the DC component of the fourth detection signal, wherein the fourth detection signal is used to reflect the intensity of the partial optical signal reflected to the optical link and the intensity of the background signal in the optical chip.

7. The optical link reflected light monitoring device according to claim 6, characterized in that, The beam splitter is used to proportionally split the optical signal reflected to the optical link into the first optical signal and the second optical signal; and / or The phase modulator includes a phase shifter based on radio frequency drive source modulation; and / or, Both the beam splitter and the beam combiner include a multimode interferometer.

8. A method for monitoring reflected light in an optical link, characterized in that, The method includes: A first detection signal in the optical link is determined, wherein the first detection signal is used to reflect the intensity of the optical signal reflected from the emitted optical signal at the optical transmitter to the optical link, and the intensity of the background signal in the optical chip; A second detection signal in the optical link is determined, wherein the second detection signal is used to reflect the background signal intensity in the optical chip; The intensity of reflected light in the optical link is determined based on the first detection signal and the second detection signal.

9. The method for monitoring reflected light in an optical link according to claim 8, characterized in that, The method specifically includes: The first detection signal is determined based on the first detector, wherein the first detector is coupled to the optical signal reflected to the optical link; The second detection signal is determined based on the second detector, wherein the second detector is not coupled to the optical signal reflected to the optical link, and the second detector is arranged adjacent to the first detector to receive the same background signal in the optical link; The intensity of reflected light in the optical link is determined based on the difference between the first detection signal and the second detection signal.

10. The method for monitoring reflected light in an optical link according to claim 9, characterized in that, The method further includes: The acquisition module acquires the first detection signal and the second detection signal respectively to determine the difference between the first detection signal and the second detection signal.

11. The method for monitoring reflected light in an optical link according to claim 10, characterized in that, The first detector and the second detector are connected in parallel.

12. The method for monitoring reflected light in an optical link according to claim 9, characterized in that, The method further includes: The difference between the first detection signal and the second detection signal is collected by the acquisition module.

13. The method for monitoring reflected light in an optical link according to claim 12, characterized in that, The first detector and the second detector are connected in series, and the acquisition module is connected to the output node between the first detector and the second detector.

14. A method for monitoring reflected light in an optical link, characterized in that, The method includes: A third detection signal in the optical link is determined, wherein the third detection signal is used to reflect the intensity of the optical signal reflected from the emitted optical signal at the optical transmitter to the optical link, and the intensity of the background signal in the optical chip; A fourth detection signal in the optical link is determined, wherein the fourth detection signal is used to reflect the intensity of a portion of the optical signal reflected from the emitted optical signal at the optical transmitter to the optical link, and the intensity of the background signal in the optical chip; The intensity of reflected light in the optical link is determined based on the third detection signal and the fourth detection signal.

15. The method for monitoring reflected light in an optical link according to claim 14, characterized in that, The method specifically includes: The optical signal reflected to the optical link is split into a first optical signal and a second optical signal; The second optical signal is phase-modulated, and the first optical signal and the phase-modulated second optical signal are combined into a third optical signal; The third optical signal is coupled into the third detector to determine the third detection signal; The third detection signal is filtered to remove the DC component of the fourth detection signal, thereby determining the intensity of reflected light in the optical link.

16. The method for monitoring reflected light in an optical link according to claim 15, characterized in that, The method specifically includes: The optical signal reflected to the optical link is proportionally split into the first optical signal and the second optical signal using a beam splitter; and / or... The second optical signal is phase-modulated by a phase shifter based on radio frequency driving source modulation.

17. An optical module, characterized in that, Includes the optical link reflection monitoring device as described in any one of claims 1 to 7.

18. The optical module according to claim 17, characterized in that, The optical module includes at least two optical transmitters and at least two corresponding optical link reflection monitoring devices, wherein the at least two optical link reflection monitoring devices share the same acquisition module.

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