Measurement System and Method for Measuring Effective Emission Length of Emission Grating

Abstract

The present invention provides a measurement system and method for the effective emission length of an emission grating. The measurement system includes: an input light coupler, an optical beam splitter, a first output light coupler, and a second output light coupler; wherein the input light coupler is used to receive an incident light beam; the optical beam splitter is connected to the input light coupler and has a first splitting end and a second splitting end, and the first splitting end is connected to an emission grating, and the first output light coupler is connected to the emission grating to emit the first split light beam after attenuation by the emission grating as a first output light beam; the second output light coupler is connected to the second splitting end to emit a second output light beam. The measurement system and method for the effective emission length of an emission grating provided by the present invention can solve the problem that the effective emission length of a prepared emission grating is inconsistent with the grating length obtained by simulation design due to process errors, and the accurate effective emission length of the emission grating cannot be obtained.

Description

Technical Field

[0001] The present invention relates to the field of laser radar, and in particular to a system and method for measuring the effective emission length of an emission grating. Background Art

[0002] Silicon-based optical phased arrays can achieve fast, arbitrary position scanning and are one of the important solutions for realizing all-solid-state lidar. Common silicon-based optical phased arrays transmit light beams through a transmitting unit to achieve beam scanning. How to achieve a large scanning range and high resolution of the phased array is a current research hotspot.

[0003] The resolution of an optical phased array is determined by the aperture of the transmitting array, where the effective transmitting length of the transmitting grating determines the resolution of the phased array's longitudinal scanning. Therefore, in order to improve the resolution of an optical phased array beam scanning, increasing the effective transmitting length of the transmitting grating is an effective way.

[0004] Among them, a large amount of research work has been proposed on the simulation method of the emission grating. However, due to the etching depth error, mask alignment error, waveguide side wall roughness and other reasons caused by process preparation, the actual effective emission length of the emission grating is inconsistent with the simulation results. Therefore, a detection method for testing the effective emission length of the emission grating is needed. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide a measurement system and method for the effective emission length of an emission grating, which is used to solve the problem that the effective emission length of the emission grating prepared due to process errors is inconsistent with the grating length obtained by simulation design, and the accurate effective emission length of the emission grating cannot be correctly obtained.

[0006] To achieve the above-mentioned and other related purposes, the present invention provides a system for measuring the effective emission length of an emission grating, which is connected to the emission grating and is used to measure the effective emission length of the emission grating. The system for measuring the effective emission length of the emission grating includes: an input light coupler, an optical beam splitter, a first output light coupler, and a second output light coupler; wherein,

[0007] The input light coupler is used to receive an incident light beam;

[0008] The optical beam splitter is connected to the optical coupler and has a first splitting end and a second splitting end, and is used to split the incident light beam into a first splitting light beam and a second splitting light beam, wherein the first splitting light beam and the second splitting light beam have a fixed optical power ratio, and the first splitting end is connected to the emission grating;

[0009] The first light output coupler is connected to the emission grating, and is used to output the first split light beam after attenuation by the emission grating as a first output light beam;

[0010] The second light-emitting coupler is connected to the second light-splitting end, and is used to emit the second split light beam as a second output light beam.

[0011] Optionally, the input optical coupler, the first output optical coupler and the second output optical coupler are grating couplers.

[0012] Optionally, the measurement system further includes: a light source and an incident optical fiber; wherein the light source is connected to the incident optical fiber, and the incident optical fiber is coupled to the light input coupler.

[0013] Optionally, the measurement system further includes: a first output optical fiber, a second output optical fiber and an optical power measurement device; wherein,

[0014] The first output optical fiber is coupled to the first output light coupler;

[0015] The second output optical fiber is coupled to the second output light coupler;

[0016] The optical power measuring device is connected to the first outgoing optical fiber and the second outgoing optical fiber to measure the optical power of the first outgoing light beam and the second outgoing light beam.

[0017] Optionally, the optical power measuring device is an optical power meter or a spectrometer.

[0018] Optionally, the ratio of the optical power of the first split beam to the optical power of the second split beam is 1:1.

[0019] The present invention also provides a method for measuring the effective emission length of an emission grating, characterized in that the measurement method comprises:

[0020] Constructing a measurement system as described in any of the preceding items, wherein an incident light beam is split by the light beam splitter into a first split light beam and a second split light beam, wherein the first split light beam and the second split light beam have a fixed optical power ratio;

[0021] Connecting the first light splitting end to the emission grating and the first light output coupler to the emission grating to measure the optical power of the first output light beam; and connecting the second light splitting end to the second light output coupler to measure the optical power of the second output light beam;

[0022] The effective emission length of the emission grating is calculated based on the optical power ratio of the first split beam and the second split beam, the optical power of the first exit beam, the optical power of the second exit beam, and the length of the emission grating.

[0023] Optionally, the method for obtaining the optical power ratio of the first split beam to the second split beam includes:

[0024] Connecting the first light splitting end to the first optical coupler, and connecting the second light splitting end to the second optical coupler;

[0025] The optical power of the first split light beam is obtained by measuring the optical power of the light emitted by the first optical coupler, and the optical power of the second split light beam is obtained by measuring the optical power of the light emitted by the second optical coupler.

[0026] Optionally, the effective emission length L of the emission grating is calculated based on the following formula 1: neff ,

[0027]

[0028] Among them, P out1 Expressed as the optical power of the first outgoing beam, P out2 Expressed as the optical power of the second outgoing beam, P bs1 Expressed as the optical power of the first split beam, P bs2 is the optical power of the second split beam, L is the length of the emission grating, and L neff It is expressed as the effective emission length of the emission grating.

[0029] As described above, the measurement system and method of the effective emission length of the emission grating of the present invention are provided with an optical beam splitter, which splits the incident light into a first split beam and a second split beam with a fixed optical power ratio. The first split beam enters the emission grating, and its light intensity decays exponentially along the propagation direction and is emitted as a first output beam. The second split beam does not pass through the emission grating and is emitted as a second output beam. The effective emission length of the emission grating can be calculated from the optical power ratio of the first output beam and the second output beam, which is in line with actual application conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Shown is a schematic structural diagram of the emission grating effective emission length measurement system of the present invention.

[0031] Figure 2 It shows a schematic structural diagram of measuring the optical power ratio of the first split light beam and the second split light beam according to the present invention.

[0032] Component number description

[0033] 10 Emission grating effective emission length measurement system

[0034] 100 input optical coupler

[0035] 200 optical beam splitter

[0036] 210 First optical splitter

[0037] 220 Second splitter end

[0038] 300 emission grating

[0039] 400 First output optical coupler

[0040] 500 Second output optical coupler DETAILED DESCRIPTION

[0041] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0042] See also Figures 1 to 2 It should be noted that the illustrations provided in this embodiment are only used to schematically illustrate the basic concept of the present invention. Therefore, the illustrations only show components related to the present invention and are not drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0043] Example 1

[0044] This embodiment provides a transmission grating effective transmission length measurement system 10, which is connected to the transmission grating 300 and is used to measure the effective transmission length of the transmission grating 300. Figure 1 As shown, the measurement system 10 includes an input optical coupler 100 , an optical beam splitter 200 , a first output optical coupler 400 , and a second output optical coupler 500 .

[0045] In this embodiment, the length L of the emission grating 300 is preset using an optical simulation method before design and production. According to the simulation preset, the optical power is P bs1 The first outgoing beam I out1 When the light beam is incident on the emission grating 300 and emitted from the emission grating 300 (the optical path of the light beam is L), the output light power P out1 Will decay to P bs1 *e -2However, due to the etching depth error, mask alignment error, waveguide side wall roughness and other reasons caused by the process preparation, the first output beam I out1 When emitted from the emission grating 300, the optical power is not equal to P bs1 *e -2 (Usually, it is better than P bs1 *e -2 Therefore, it is necessary to obtain the first outgoing light beam I by the measurement system described in this embodiment. out1 After incident on the emission grating 300, the optical power decays to P bs1 *e -2 The exact position of the emission grating 300, that is, the actual effective emission length L neff (The effective launch length is defined as the time from the incident light power decaying to the initial value e -2 The test principle is as follows:

[0046] The emission grating 300 is regarded as a grating with a uniform diffraction structure, and its perturbation intensity is a constant α0, and the power of a beam of light is P bs1 The relationship between the distance x of the light beam propagating along the emission grating and the remaining optical power P(x) at position x can be expressed as:

[0047]

[0048] Assume that x = L neff The position of the first outgoing light beam I out1 The optical power attenuation is P bs1 *e -2 , so P(x)=P0*e -2 Substituting into formula 2, we can get:

[0049] L neff =1 / α0···[Formula 3];

[0050] And, as Figure 2 As shown, the first splitting end 210 is connected to the first optical coupler 400, and the second splitting end 220 is connected to the second optical coupler 500, and the first splitting beam I can be measured. bs1 The optical power P bs1 With the second split beam I bs2 The optical power P bs2 .

[0051] At the same time, if Figure 2 As shown, the first light splitting end 210 is connected to the light input end of the emission grating 300, the light output end of the emission grating 300 is connected to the first optical coupler 400, and the second light splitting end 220 is connected to the second optical coupler 500, and the first outgoing light beam I can be measured. out1The optical power P out1 With the second outgoing beam I out2 The optical power P out2 , where P out2 =P bs2 , and we can know that

[0052]

[0053] Substituting Equation 3 into Equation 4, we can obtain the following Equation 1:

[0054]

[0055] The effective emission length L of the emission grating 300 can be calculated from formula 1: neff , to meet the actual application of the emission grating 300.

[0056] In some embodiments, the measurement system 10 for the effective emission length of the emission grating is integrated into a silicon photonic device. In this case, the optical coupler 100 can be a grating coupler, and the incident light beam I emitted by the light source (laser) outside the silicon photonic device is in The light output from the incident fiber is incident on the light input of the grating coupler, which can effectively improve the coupling efficiency and is suitable for wafer-level parameter testing.

[0057] Based on the same configuration, the first optical coupler 400 and the second optical coupler 500 also use grating couplers. out1 And the second outgoing light beam I out2 The light emitted from the light outlet of the grating coupler is received by two subsequent output optical fibers and enters a subsequent optical power measurement device to measure the optical power. The optical power measurement device can be an optical power meter or a spectrometer.

[0058] In some embodiments, the optical beam splitter 200 may be a multimode interference coupler, a Y-type splitter or a directional coupler, and has at least two splitting ends (a first splitting end 210 and a second splitting end 220) for splitting the incident light beam I in The beam is split into two first split beams I with a fixed optical power ratio bs1 and the second split beam I bs2 , wherein the first split beam I bs1 The optical power is P bs1 , the second split beam I bs2 The optical power is P bs2 The ratio of the optical power of the two is K=P bs1 / P bs2 In some preferred embodiments, K=1, that is, the optical beam splitter 200 uses a 1×2 optical beam splitter with a power ratio of 0.5:0.5. At this time, P out2 =Pbs2 =P bs1 .

[0059] Example 2

[0060] This embodiment provides a method for measuring the effective emission length of an emission grating. When the emission grating length does not match the actual effective emission length due to factors such as the preparation process (transmission loss caused by factors such as waveguide side wall roughness), this measurement method can accurately calculate the effective emission length to meet actual application conditions. The steps of the measurement method include steps S1) to S3).

[0061] Step S1), providing the measurement system 10 as described in the first embodiment, the incident light beam I in The beam is passed through the beam splitter 200 to form a first split beam I bs1 and the second split beam I bs2 , wherein the first split beam I bs1 With the second split beam I bs2 Has a fixed optical power ratio.

[0062] In this embodiment, a light source, an incident optical fiber, an output optical fiber, an optical power measurement device and the measurement system 10 described in the first embodiment are first provided. If the fixed splitting ratio of the prepared optical beam splitter 200 (the first split beam I bs1 With the second split beam I bs2 If the optical power ratio of the optical beam splitter 200 is 1:1, for example, it is no longer necessary to test the fixed splitting ratio of the optical beam splitter 200. Otherwise, the following steps S11) to S2) need to be used to obtain the fixed splitting ratio of the optical beam splitter 200:

[0063] In step S11 , the first light splitting end 210 is directly connected to the first optical coupler 400 , and the second light splitting end 220 is directly connected to the second optical coupler 500 .

[0064] Step S12), measure the optical power of the light emitted by the first optical coupler 400 to obtain the optical power P of the first split beam bs1 Measure the optical power of the second optical coupler to obtain the optical power P of the second split beam bs2 , and thereby obtain the fixed splitting ratio of the optical beam splitter 200.

[0065] Step S2), connecting the first light splitting end 210 to the emission grating 300, and connecting the first light coupler 400 to the emission grating 300, and measuring the first emitted light beam I out1 The optical power P out1 At the same time, the second splitter end 220 is connected to the second optical coupler 500, and the second outgoing beam I is measured. out2The optical power P out2 .

[0066] In this embodiment, since the splitting ratio of the optical beam splitter 200 is fixed, the optical power P of the second outgoing light beam is out2 The size of the second split beam is related to the optical power P bs2 are the same size.

[0067] Step S3), based on the optical power P of the first split beam bs1 The optical power P of the second split beam bs2 The proportion P bs1 / P bs2 , the optical power P of the first outgoing light beam out1 , the optical power P of the second outgoing light beam out2 The effective emission length L of the emission grating is calculated as neff .

[0068] In this embodiment, the test principle of the measurement system 10 described in the first embodiment can be obtained:

[0069]

[0070] Among them, the P out1 Expressed as the optical power of the first outgoing light beam, the P out2 Expressed as the optical power of the second outgoing beam, the P bs1 is represented by the optical power of the first split beam, the P bs2 is represented by the optical power of the second split beam, L is represented by the length of the emission grating, and L neff It is expressed as the effective emission length of the emission grating.

[0071] In the known P bs1 、P bs2 、P out1 、P out2 and the numerical value of L, the effective emission length L of the emission grating can be calculated by formula 1 neff .

[0072] In summary, the measurement system and method of the effective emission length of the emission grating of the present invention are provided with an optical beam splitter, which splits the incident light into a first split beam and a second split beam with a fixed optical power ratio. The first split beam enters the emission grating, and its light intensity decays exponentially along the propagation direction, and is emitted as a first output beam. The second split beam does not pass through the emission grating and is emitted as a second output beam. The effective emission length of the emission grating can be calculated from the optical power ratio of the first output beam and the second output beam, which is in line with actual application conditions.

[0073] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A system for measuring the effective emission length of an emission grating, connected to an emission grating, for measuring the effective emission length of the emission grating, characterized in that: The emission grating effective emission length measurement system includes: an input light coupler, an optical beam splitter, a first output light coupler and a second output light coupler; wherein, The input light coupler is used to receive an incident light beam; The optical beam splitter is connected to the optical coupler and has a first splitting end and a second splitting end, and is used to split the incident light beam into a first splitting light beam and a second splitting light beam, wherein the first splitting light beam and the second splitting light beam have a fixed optical power ratio, and the emission grating is connected to the first splitting end; The first light output coupler is connected to the emission grating, and is used to output the first split light beam after attenuation by the emission grating as a first output light beam; The second light-emitting coupler is connected to the second light-splitting end, and is used to emit the second split light beam as a second output light beam.

2. The measuring system for the effective emission length of the emission grating according to claim 1, characterized in that: The input optical coupler, the first output optical coupler and the second output optical coupler are grating couplers.

3. The measuring system for the effective emission length of the emission grating according to claim 1, characterized in that: The measurement system further includes: a light source and an incident optical fiber; wherein, The light source is connected to the incident optical fiber, and the incident optical fiber is coupled to the light input coupler.

4. The measuring system for the effective emission length of the emission grating according to claim 1, characterized in that: The measurement system further includes: a first output optical fiber, a second output optical fiber and an optical power measurement device; wherein, The first output optical fiber is coupled to the first output light coupler; The second output optical fiber is coupled to the second output light coupler; The optical power measuring device is connected to the first outgoing optical fiber and the second outgoing optical fiber to measure the optical power of the first outgoing light beam and the second outgoing light beam.

5. The system for measuring the effective emission length of an emission grating according to claim 4, characterized in that: The optical power measuring device adopts an optical power meter or a spectrometer.

6. The system for measuring the effective emission length of an emission grating according to claim 1, characterized in that: The ratio of the optical power of the first split beam to the optical power of the second split beam is 1:

1.

7. A method for measuring the effective emission length of an emission grating, characterized in that: The measuring method comprises: Constructing a measurement system according to any one of claims 1 to 6, wherein an incident light beam is split by the optical beam splitter into a first split light beam and a second split light beam, wherein the first split light beam and the second split light beam have a fixed optical power ratio; Connecting the first light splitting end to the emission grating and the first light output coupler to the emission grating to measure the optical power of the first output light beam; and connecting the second light splitting end to the second light output coupler to measure the optical power of the second output light beam; The effective emission length of the emission grating is calculated based on the optical power ratio of the first split beam and the second split beam, the optical power of the first exit beam, the optical power of the second exit beam, and the length of the emission grating.

8. The method for measuring the effective emission length of an emission grating according to claim 7, characterized in that: The method for obtaining the optical power ratio of the first split beam to the second split beam includes: Connecting the first light splitting end to the first optical coupler, and connecting the second light splitting end to the second optical coupler; The optical power of the first split light beam is obtained by measuring the optical power of the light emitted by the first optical coupler, and the optical power of the second split light beam is obtained by measuring the optical power of the light emitted by the second optical coupler.

9. The method for measuring the effective emission length of an emission grating according to any one of claims 7 to 8, characterized in that: The effective emission length L of the emission grating is calculated based on the following formula 1 neff , Among them, P out1 Expressed as the optical power of the first outgoing beam, P out2 Expressed as the optical power of the second outgoing beam, P bs1 Expressed as the optical power of the first split beam, P bs2 is the optical power of the second split beam, L is the length of the emission grating, and L neff It is expressed as the effective emission length of the emission grating.

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