A noise correction system and noise correction method for optical chip testing

Abstract

The present invention discloses a noise correction system for optical chip testing, including a light source module, a polarization control module, an optical power monitoring module, an optical transmission module and an optical power detection module; the light source module outputs a light beam for optical chip testing and is incident on the polarization control module; the polarization control module modulates the output light beam of the light source module into light with a specific polarization state; the optical power monitoring module is used to monitor and detect the output optical power of the polarization control module; the optical transmission module is used to connect the optical power monitoring module and the optical power detection module; the optical power detection module is used to test and record the output optical power of the optical transmission module. The present invention also discloses a noise correction method for optical chip testing. Advantages: the system is a multi-light intensity test system and requires calibrated optical devices for calibration; the method performs polynomial fitting on the optical chip measurement noise through the linear perturbation theory of the chip test system to achieve noise correction of the optical chip test system.

Description

Technical Field

[0001] The present invention relates to the field of optical chip testing, and in particular to a noise correction system and a noise correction method applied to optical chip testing. Background Art

[0002] As the most promising carrier in the "post-Moore" era, optical chips have played a vital role in scientific and technological progress and social development. Especially in the field of optical communications, optical chips are one of the core devices that realize the transmission, modulation and reception of signals in long-distance communications and high-speed communications. At the same time, optical computing based on optical chips has also attracted much attention from academia and industry at home and abroad. Here, optical chips are given more functions and have achieved more diverse development. Optical chips can be divided into design, processing, testing and packaging processes, among which the testing process can be used to characterize the performance of optical chips, and then evaluate the reliability and consistency of optical chips in large-scale production. In addition, the processing of optical chips is based on CMOS technology, and the actual processing process is unobservable. The detection of optical chips is also the most direct and effective way to achieve process feedback.

[0003] The test system for optical chips (including optical devices) is relatively complex and requires monitoring of both input and output optical powers. The inclination angle and roughness of the cut end face of the optical fiber directly affect the measurement results of the optical chip. Fiber connection flanges, beam splitters, polarization controllers, polarization analyzers and other equipment are all necessary equipment for optical chip measurement, which will introduce additional noise into the measurement system. This results in, firstly, even if the test system has the same composition, there will be certain differences in the test results of the same optical chip on different test platforms; secondly, the test results of the same optical chip will drift over time. The noise introduced by the complexity of the optical chip test system and the diversity of the test system greatly affects the characterization and evaluation of the performance of the optical chip. What's more, excessive system test noise will directly reduce the yield of the optical chip. Summary of the invention

[0004] The technical problem to be solved by the present invention is: the noise introduced by the complexity of the known optical chip testing system and the diversity of the testing system greatly affects the characterization and evaluation of the optical chip performance. What's worse, excessive system testing noise will directly reduce the yield of the optical chip.

[0005] In order to solve the above technical problems, the first purpose of the present invention is to provide a noise correction system for optical chip testing, which is a multi-light intensity testing system and requires calibrated optical devices for calibration.

[0006] The specific technical solutions adopted are as follows:

[0007] A noise correction system for optical chip testing comprises a light source module, a polarization control module, an optical power monitoring module, an optical transmission module and an optical power detection module. The light source module outputs a light beam for optical chip testing, the output light beam has a single wavelength characteristic and is incident on the polarization control module; the polarization control module modulates the output light beam of the light source module into a light beam with a specific polarization state and keeps the polarization state of the light beam stable; the optical power monitoring module is used to monitor and detect the output light power of the polarization control module and also realizes the propagation of the light beam in the system; the optical transmission module is used to connect the optical power monitoring module and the optical power detection module; the optical power detection module is used to test and record the output light power of the optical transmission module.

[0008] In a further preferred embodiment of the technical solution of the present invention, the light source module is a single-wavelength laser with adjustable optical power, so as to ensure that the optical power of the incident system is adjustable.

[0009] In a further embodiment of the technical solution of the present invention, the polarization control module includes a polarization analyzer and a three-ring polarization controller, wherein the polarization analyzer adjusts the polarization state of the output light of the light source module, and the three-ring polarization controller maintains the stability of the polarization state of the light beam and reduces the noise introduced by the polarization of the light beam.

[0010] In a further preferred embodiment of the technical solution of the present invention, the optical power monitoring module includes a light splitting device and a photoelectric detector, and the light splitting device is configured to split the light according to a fixed light splitting ratio. SR The input light is divided into two beams: one for strong light and one for weak light. The photodetector monitors the optical power of the weak light path and calculates the light power according to the fixed splitting ratio. SR Calculate the optical power from the polarization control module to the optical power monitoring module; the strong light path is the main optical path of the optical chip test system, connected to the optical transmission module. On the one hand, it realizes the monitoring of the incident light power, and at the same time ensures that there is enough strong light power to realize the noise correction of the optical chip test system.

[0011] In a further embodiment of the technical solution of the present invention, the optical power monitoring module realizes a fixed splitting ratio. SR Satisfies the following relationship: .

[0012] In a further preferred embodiment of the technical solution of the present invention, the optical transmission module includes a calibration optical device, and the calibration optical device includes the following features: ;

[0013] in, Respectively TE Modulus or TM The loss of the mode beam passing through the optical device. The calibration optical device has this feature, which can improve the accuracy of the calibration system.

[0014] In a further preferred embodiment of the technical solution of the present invention, the optical power detection module includes a photodetector, and the dark current of the photodetector is less than , It is a limit value of dark current, a constraint on detector performance.

[0015] The second purpose of the present invention is to propose a noise correction method for optical chip testing, the responsiveness of the optical chip testing system under different polarization states, and the noise correction of the optical chip testing system by performing polynomial fitting on the optical chip measurement noise through the linear perturbation theory of the chip testing system.

[0016] The technical solutions adopted are as follows:

[0017] A noise correction method for optical chip testing includes the following steps:

[0018] Step 1: The optical chip testing system measures the polarization responsivity of the calibration optical device in different polarization states to obtain measurement data;

[0019] Step 2: Based on the measured data in step 1, define the polarization responsivity linear equations as follows: ;

[0020] It can also be expressed as:

[0021] ;

[0022] in, A is a 4×4 matrix; is a 4×1 column vector, where The Mueller matrix factors obtained to solve the above system of equations; It is also a 4×1 column vector, where is the polarization responsivity measured in step 1; Record the reference optical power in four polarization states for the optical power monitoring module. The measured optical power recorded by the optical power detection module;

[0023] Step 3: Solve the polarization response linear equations in step 2 and obtain , and then calculate the noise of the Mueller matrix factor ,as follows: ;

[0024] in, is a 4×1 column vector, which is the ideal Mueller matrix factor for calibrating optical devices and does not contain noise;

[0025] Step 4: Construct a polarization responsivity noise model for the optical chip test system ,as follows:

[0026] ;

[0027] in, is a 4×1 column vector, representing the polarization response linear equations in the above The measurement noise involved; are the parameters of the second-order noise model, is a real number; so the ideal polarization responsivity of the optical chip test system can be expressed as follows:

[0028] ;

[0029] in, is a 4×1 column vector, containing no noise;

[0030] Step 5: Construct a polarization responsivity noise disturbance model for the optical chip test system. According to the product inequality of the matrix norm, the noise disturbance model can be transformed into the following form:

[0031] ;

[0032] in, express A The inverse matrix of is a real number, which is related to the polarization-dependent loss of the calibration optical device; represents the matrix norm;

[0033] Step 6: Repeat steps 1 to 5 N In each cycle, the output optical power of the light source module is different, and finally the N Group observation data points;

[0034] Step 7, Fitting N A set of observation data points is used to derive the polarization responsivity noise model of the optical chip test system. Parameters , realize the noise correction of optical chip test system and obtain the ideal polarization responsivity ; According to the polarization responsivity linear equations, the ideal polarization responsivity The ideal Mueller matrix factor can be solved to characterize the optical transmission characteristics of the optical chip.

[0035] Further improvement of the noise correction method of the present invention, the specific method of step 1 is as follows: the optical path of the optical chip test system is connected, the polarization state of the output light beam of the polarization control module is adjusted to 0° linear polarization, 90° linear polarization, 45° linear polarization and -45° linear polarization, and the optical power monitoring module records the reference light power under the four polarization states as follows: ; The optical power detection module records the measured optical power .

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The noise correction system for optical chip testing of the present invention inserts a calibration optical device on the basis of a general optical chip testing system to calibrate the optical chip testing system. The system is not only suitable for noise correction of the optical chip testing system, but can also be used for conventional testing of optical chips.

[0038] The noise correction method of the present invention constructs a system noise disturbance model based on the polarization measurement of the optical chip, and establishes a relative noise equation for the measurement loss of the optical chip; multiple measurements are performed to establish observation data points, and the coefficients of the system noise disturbance model can be solved by data fitting; this method greatly simplifies the noise correction process of a general chip measurement system, improves the accuracy of chip testing, and at the same time, the method has low hardware requirements for the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 is a schematic diagram of a noise correction system for an optical chip testing system in an embodiment of the present invention;

[0040] Figure 2 is a flow chart of a noise correction method for an optical chip testing system in an embodiment of the present invention;

[0041] Figure 3 is a fitting curve of the data observation point and the noise disturbance model in the embodiment of the present invention;

[0042] Among them, 1-light source module; 2-polarization control module; 3-optical power monitoring module; 4-optical transmission module; 5-optical power detection module. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the following Figure 1-Figure 3 The present invention is further described in detail with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in each embodiment of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0044] like Figure 1 As shown, the noise correction system for optical chip testing proposed in this embodiment includes the following modules:

[0045] Light source module 1, polarization control module 2, optical power monitoring module 3, optical transmission module 4 and optical power detection module 5;

[0046] The output light beam of the light source module 1 is used for optical chip testing. The output light beam has a single wavelength characteristic and is incident on the polarization control module 2. The polarization control module 2 modulates the output light beam of the light source module 1 into a light beam with a specific polarization state and keeps the polarization state of the light beam stable. The optical power monitoring module 3 is used to monitor and detect the output light power of the polarization control module 2, and also realizes the propagation of the light beam in the system. The optical transmission module 4 is used to connect the optical power monitoring module 3 and the optical power detection module 5. The optical power detection module 5 is used to test and record the output light power of the optical transmission module 4.

[0047] In this embodiment, the light source module 1 is a single-wavelength laser with adjustable optical power. The polarization control module 2 includes a polarization analyzer and a three-ring polarization controller, wherein the polarization analyzer adjusts the polarization state of the output light of the light source module 1 and the three-ring polarization controller maintains the stability of the polarization state of the light beam.

[0048] In this embodiment, the optical power monitoring module 3 includes a spectrometer and a photodetector. The spectrometer divides the input light into two light beams according to a fixed splitting ratio SR: one strong light and one weak light. The photodetector monitors the optical power of the weak light path and calculates the optical power of the polarization control module 2 input to the optical power monitoring module 3 according to the fixed splitting ratio SR. The strong light path is the main optical path of the optical chip testing system and is connected to the optical transmission module 4.

[0049] The fixed splitting ratio SR implemented by the optical power monitoring module 3 satisfies the following relationship: .

[0050] The optical transmission module 4 includes a calibration optical device, which has the following features: ,

[0051] in, Respectively TE Modulus or TM The loss of a mode light beam passing through an optical device.

[0052] The optical power detection module 5 includes a photodetector, the dark current of which is less than , It is a limit value of dark current.

[0053] In the embodiment, Figure 2 As shown, a noise correction method applied to optical chip testing includes the following steps:

[0054] Step 1: The optical chip test system measures the polarization responsivity of the calibration optical device in different polarization states to obtain measurement data; specifically: the optical path of the optical chip test system is connected, the polarization state of the output light beam of the polarization control module 2 is adjusted to 0° linear polarization, 90° linear polarization, 45° linear polarization and -45° linear polarization, and the optical power monitoring module 3 records the reference light power in the four polarization states as follows: ; Optical power detection module 5 records the measured optical power .

[0055] Step 2: Based on the measured data in step 1, define the polarization responsivity linear equations as follows: (1-1);

[0056] It can also be expressed as:

[0057] (1-2);

[0058] in, A is a 4×4 matrix; is a 4×1 column vector, where The Mueller matrix factors obtained to solve the above system of equations; It is also a 4×1 column vector, where Testing the polarization responsivity of the system for optical chips; The optical power monitoring module 3 records the reference optical power under four polarization states. The measured optical power recorded by the optical power detection module 5;

[0059] Step 3: Solve the polarization response linear equations of step 2 according to the test data of step 1, and obtain , and then calculate the noise of the Mueller matrix factor ,as follows: (2),

[0060] in, It is the ideal Mueller matrix factor for calibrating optical devices and does not contain noise;

[0061] Step 4: Construct a polarization responsivity noise model for the optical chip test system ,as follows:

[0062] (3-1);

[0063] in, is a 4×1 column vector, representing the polarization response linear equations in the above The measurement noise involved; are the linear parameters of the noise model, is a real number. Therefore, the ideal polarization responsivity of the optical chip test system can be expressed as follows: (3-2);

[0064] in, is a 4×1 column vector, containing no noise;

[0065] Step 5: Construct a polarization responsivity noise disturbance model for the optical chip test system as follows:

[0066] (4-1);

[0067] The above noise disturbance model (4-1) is split into two parts: signal and noise. According to the product inequality of matrix norm, the noise disturbance model can be transformed into the following form by combining the two equations:

[0068] (4-2);

[0069] in, express A The inverse matrix of Represents the matrix norm, where the infinite norm is taken. is a matrix A Condition number. Substituting equations (3-1), (3-2) and (2) into equation (4-2), we can finally get the fitting function of the parameters of the noise disturbance model, as follows: (4-3);

[0070] According to the polarization characteristics of the calibration optical device, the coefficient ;

[0071] Step 6: Repeat steps 1 to 5 10 times. In each cycle, the output optical power of the light source module 1 is different, which are , and finally get the corresponding 10 groups of observation data points ;

[0072] Step 7: Fit 10 sets of observation data points to obtain the polarization responsivity noise model of the optical chip test system The parameters are ; According to formula (3-2), the ideal polarization response can be obtained , thereby realizing the noise correction of the optical chip test system. According to formula (1-2), the ideal value of the Mueller matrix factor can be further obtained, which can almost perfectly characterize the optical transmission characteristics of the optical chip.

[0073] In the noise correction system and method for optical chip testing proposed in this embodiment, any form of function can be expanded using a polynomial, so the above noise model can approximately describe the noise of the test system. A system noise perturbation model is constructed based on the polarization measurement of the optical chip, and finally a relative noise equation for the optical chip measurement loss is established. Finally, the output optical power of the light source module is changed for multiple measurements to obtain N groups of observation data points, and the coefficients of the system noise perturbation model are solved by data fitting.

[0074] The system is not only suitable for noise correction of optical chip test systems, but also can be used for conventional testing of optical chips. In general, the noise correction system and method for optical chip testing proposed in the present invention are simple in system and method, which helps to improve the accuracy of chip testing.

[0075] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A noise correction method for optical chip testing, characterized in that: The steps include: Step 1: The optical chip testing system measures the polarization responsivity of the calibration optical device in different polarization states to obtain measurement data; Step 2: Based on the measured data in step 1, define the polarization responsivity linear equations as follows: ， It can also be expressed as: ； in, A for matrix; for A column vector of The Mueller matrix factors obtained to solve the above system of equations; Likewise A column vector of is the polarization responsivity measured in step 1; The optical power monitoring module (3) records the reference optical power in four polarization states. The measured optical power recorded by the optical power detection module (5); Step 3: Solve the polarization response linear equations in step 2 and obtain , and then calculate the noise of the Mueller matrix factor ,as follows: ， in, for The column vector of is the ideal Mueller matrix factor for calibrating optical devices and does not contain noise; Step 4: Construct a polarization responsivity noise model for the optical chip test system ,as follows: ， in, for The column vector represents the linear equations of polarization responsivity above. The included measurement noise; are the parameters of the second-order noise model, is a real number; so the ideal polarization responsivity of the optical chip test system can be expressed as follows: ， in, for Column vector of , excluding noise; Step 5: Construct a polarization responsivity noise disturbance model for the optical chip test system. According to the product inequality of the matrix norm, the noise disturbance model can be transformed into the following form: ， in, express A The inverse matrix of is a real number, which is related to the polarization-dependent loss of the calibration optical device; represents the matrix norm; Step 6: Repeat steps 1 to 5. In each cycle, the output optical power of the light source module (1) is different, and finally Group observation data points; Step 7, Fitting A set of observation data points is used to derive the polarization responsivity noise model of the optical chip test system. Parameters , realize the noise correction of optical chip test system and obtain the ideal polarization responsivity ; The chip testing system comprises a light source module (1), a polarization control module (2), an optical power monitoring module (3), an optical transmission module (4) and an optical power detection module (5). The light source module (1) outputs a light beam for optical chip testing, the output light beam has a single wavelength characteristic and is incident on a polarization control module (2); the polarization control module (2) modulates the output light beam of the light source module (1) into a light beam with a specific polarization state and maintains the polarization state of the light beam stable; the optical power monitoring module (3) is used to monitor and detect the output light power of the polarization control module (2), and also realizes the propagation of the light beam in the system; the optical transmission module (4) is used to connect the optical power monitoring module (3) and the optical power detection module (5); the optical power detection module (5) is used to test and record the output light power of the optical transmission module (4).

2. The noise correction method according to claim 1, characterized in that: The light source module (1) is a single-wavelength laser with adjustable optical power.

3. The noise correction method according to claim 1, characterized in that: The polarization control module (2) comprises a polarization analyzer and a three-ring polarization controller, wherein the polarization analyzer adjusts the polarization state of the output light of the light source module (1), and the three-ring polarization controller maintains the stability of the polarization state of the light beam.

4. The noise correction method according to claim 1, characterized in that: The optical power monitoring module (3) includes a light splitter and a photodetector. The light splitter is configured to split the light according to a fixed light splitting ratio. Split the input light into two beams: one for strong light and one for weak light; The photodetector monitors the optical power of the weak light path and The optical power input from the polarization control module (2) to the optical power monitoring module (3) is calculated; the strong light path is the main light path of the optical chip test system and is connected to the optical transmission module (4).

5. The noise correction method according to claim 4, characterized in that: Optical power monitoring module (3), the fixed splitting ratio achieved Satisfies the following relationship: 。 6. The noise correction method according to claim 1, characterized in that: The optical transmission module (4) includes a calibration optical device, and the calibration optical device has the following features: ； in, Respectively TE Modulus or TM The loss of a mode light beam passing through an optical device.

7. The noise correction method according to claim 1, characterized in that: The optical power detection module (5) includes a photodetector, the dark current of the photodetector is less than , It is a limit value of dark current.

8. The noise correction method according to claim 1, characterized in that: The specific method of step 1 is as follows: the optical path of the optical chip test system is connected, the polarization state of the output light beam of the polarization control module (2) is adjusted to 0° linear polarization, 90° linear polarization, 45° linear polarization and -45° linear polarization, and the optical power monitoring module (3) records the reference optical power under the four polarization states as follows: ; Optical power detection module (5) records the measured optical power .

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