CN116577073A - Measuring system and method for effective emission length of emission grating - Google Patents

Abstract

The present invention provides a measurement system and method for measuring the effective emission length of a transmission grating, the measurement system comprising: an optical input coupler, an optical beam splitter, a first output optical coupler and a second output optical coupler; wherein, the input optical coupler The optical beam splitter is used to receive the incident light beam; the optical beam splitter is connected to the light-incoming coupler, and has a first light-splitting end and a second light-splitting end, and the first light-splitting end is connected to the emission grating, and the first light-out coupler is connected to the emission grating , outputting the first split beam attenuated by the emission grating as the first outgoing beam; the second outgoing coupler is connected with the second splitting end to emit the second outgoing beam. The measurement system and method for measuring the effective emission length of the emission grating provided by the present invention can solve the problem that the effective emission length of the emission grating prepared due to process errors does not match the grating length obtained by simulation design, and the accurate effective emission length of the emission grating cannot be obtained. .

Description

Measuring system and method for effective emission length of emission grating

technical field

The invention relates to the field of laser radar, in particular to a measurement system and a measurement method for the effective emission length of an emission grating.

Background technique

Silicon-based optical phased array can realize fast scanning at any position, which is one of the important solutions to realize all-solid-state lidar; common silicon-based optical phased array emits beams through the transmitting unit to realize beam scanning, how to realize phase control Large scanning range and high resolution are the hotspots of current research.

The resolution of the optical phased array is determined by the aperture of the emission array, and the effective emission length of the emission grating determines the resolution of the longitudinal scanning of the phased array. Therefore, in order to improve the resolution of the beam scanning of the optical phased array, the increase of the emission grating The effective launch length of is an effective way.

Among them, a lot of research work has been put forward on the simulation method of the emission grating, but due to the etching depth error, mask alignment error, rough waveguide side wall and other reasons caused by the process preparation, the actual effective emission length of the emission grating is different from the simulation method. Inconsistent Results Therefore, there is thus a need for a detection method for testing the effective emission length of an emission grating.

Contents of the invention

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 measuring the effective emission length of the emission grating, which is used to solve the problem of the effective emission length and simulation design of the prepared emission grating caused by process errors. The length of the obtained grating does not match, and the accurate effective emission length of the emission grating cannot be obtained correctly.

In order to achieve the above purpose and other related purposes, the present invention provides a measurement system for the effective emission length of the emission grating, which is connected to the emission grating for measuring the effective emission length of the emission grating, and the measurement system for the effective emission length of the emission grating includes : Incoming optical coupler, optical beam splitter, first outgoing optical coupler and second outgoing optical coupler; where,

The incoming optical coupler is used to receive the incident light beam;

The optical beam splitter is connected to the optical coupler and has a first splitting end and a second splitting end for splitting the incident beam into a first splitting beam and a second splitting beam, the The first split beam and the second split beam have a fixed optical power ratio, and the first split end is connected to the emission grating;

The first output coupler is connected to the emission grating, and is used to output the first split light beam attenuated by the emission grating as a first output light beam;

The second output coupler is connected to the second light splitting end, and is used to output the second split light beam into a second output light beam.

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

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 optical input coupler.

Optionally, the measurement system further includes: a first outgoing optical fiber, a second outgoing optical fiber, and an optical power measurement device; wherein,

The first output optical fiber is coupled to the first output coupler;

The second output optical fiber is coupled to the second output coupler;

The optical power measuring device is connected with the first outgoing optical fiber and the second outgoing optical fiber, and measures the optical power of the first outgoing light beam and the second outgoing light beam.

Optionally, the optical power measuring device adopts an optical power meter or a spectrometer.

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

The present invention also provides a method for measuring the effective emission length of the emission grating, characterized in that the measurement method includes:

Building the measurement system as described in any one of the preceding items, the incident light beam is split by the optical beam splitter to form a first split beam and a second split beam, wherein the first split beam and the second split beam have a fixed The ratio of optical power;

Connect the first light splitting end to the emission grating, and connect the first optical coupler to the emission grating to measure the optical power of the first outgoing light beam; simultaneously connect the second light splitting end to the emission grating The second outgoing optical coupler is connected to measure the optical power of the second outgoing light beam;

The emission is calculated based on the optical power ratio of the first split beam to the second split beam, the optical power of the first outgoing beam, the optical power of the second outgoing beam, and the length of the emitting grating. Effective launch length of the grating

Optionally, 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 light output coupler, and connecting the second light splitting end to the second light output coupler;

measuring the optical power of the light emitted by the first optical coupler to obtain the optical power of the first split beam, and measuring the optical power of the light emitted by the second optical coupler to obtain the optical power of the second split beam.

Optionally, the effective emission length L _neff of the emission grating is calculated based on the following formula 1,

Wherein, P _out1 represents the optical power of the first outgoing light beam, P _out2 represents the optical power of the second outgoing light beam, P _bs1 represents the optical power of the first split light beam, and P _bs2 represents the optical power of the first split light beam. The optical power of the second split light beam, L represents the length of the emission grating, and L _neff represents the effective emission length of the emission grating.

As mentioned above, the measurement system and measurement method of the effective emission length of emission gratings 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 When the light beam enters the emission grating, its light intensity will decay exponentially along the direction of propagation, and it emerges as the first outgoing beam, and the second split beam exits as the second outgoing beam without passing through the emission grating. The difference between the first outgoing beam and the second outgoing beam The optical power ratio can be calculated to obtain the effective emission length of the emission grating, which is in line with the actual application situation.

Description of drawings

FIG. 1 is a schematic structural diagram of a system for measuring the effective emission length of an emission grating according to the present invention.

FIG. 2 is a schematic structural diagram of measuring the optical power ratio of the first split beam and the second split beam according to the present invention.

Component designation description

10 Measuring system for effective emission length of emission grating

100 into optocoupler

200 beam splitter

210 The first split end

220 The second splitter end

300 emission grating

400 First out optocoupler

500 2nd output optocoupler

Detailed ways

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

Please refer to Figures 1 to 2. It should be noted that the illustrations provided in this embodiment are only schematically illustrating the basic idea of the present invention, and only the components related to the present invention are shown in the drawings rather than according to actual implementation. The number, shape, and size of the components are drawn, and the type, quantity, and proportion of each component can be changed at will during actual implementation, and the layout of the components may also be more complicated.

Embodiment one

The present embodiment provides a transmission grating effective emission length measurement system 10, connected with the emission grating 300, for measuring the effective emission length of the emission grating 300, as shown in Figure 1, the measurement system 10 includes an optical coupler 100, an optical beam splitter 200, the first output coupler 400 and the second output coupler 500.

In this embodiment, the length L of the emission grating 300 has been preset using an optical simulation method before design and manufacture. According to the simulation preset, the first outgoing light beam I _out1 with an optical power of P _bs1 is incident on the emission grating 300, and is transmitted from the emission When the grating 300 exits (the optical path of the beam is L), the outgoing light power P _out1 will be attenuated to P _bs1 *e ^-2 ; however, the etching depth error, mask alignment error, waveguide side wall roughness, etc. The reason is that the optical power of the first outgoing light beam I _out1 is not equal to P _bs1 *e ^-2 (usually smaller than P _bs1 *e ^-2 ) when it emerges from the emission grating 300, therefore, it needs to be described in this embodiment The measurement system obtains the exact position where the optical power attenuation is P _bs1 *e ⁻² after the first outgoing light beam I _out1 is incident on the emission grating 300, that is, the actual effective emission length L _neff of the emission grating 300 needs to be obtained (the effective emission length is defined as The length at which the optical power of the incident light decays to e ^-2 of the initial value). The test principle is as follows:

Considering the emission grating 300 as a grating with a uniform diffraction structure, its perturbation intensity is a constant α ₀ , a light beam with optical power P _bs1 travels x along the emission grating, and the rest at position x The relationship of optical power P(x) can be expressed as:

Wherein, it is assumed that the optical power of the first outgoing light beam I _out1 can be attenuated to P _bs1 *e ^-2 at the position of x=L _neff , so substituting P(x)=P ₀ *e ^-2 into Equation 2 can be obtained:

L _neff ＝1/α ₀ ···[Formula 3];

And, as shown in Figure 2, the first splitting end 210 is connected with the first optical coupler 400, and the second splitting end 220 is connected with the second optical coupler 500, the light of the first splitting light beam I _bs1 can be measured The power P _bs1 and the optical power P _bs2 of the second split light beam I _bs2 .

Simultaneously, as shown in Figure 2, connect the first light splitting end 210 with the light entrance end of the emission grating 300, connect the light output end of the emission grating 300 with the first optical coupler 400, and connect the second light splitting end 220 with the second light splitting end 220. The optical coupler 500 is connected, and the optical power P _out1 of the first outgoing light beam I _out1 and the optical power P _out2 of the second outgoing light beam I _out2 can be measured, wherein, P _out2 =P _bs2 , and it can be seen that,

Substituting Equation 3 into Equation 4, the following Equation 1 can be obtained:

The effective emission length L _neff of the emission grating 300 can be calculated from Equation 1, so as to meet the actual application of the emission grating 300 .

In some embodiments, the measurement system 10 of the effective emission length of the emission grating is integrated in the silicon optical device. At this time, the incoming optical coupler 100 can be a grating coupler, and the incident light beam emitted by the light source (laser) outside the silicon optical device I _in is incident from the light exit of the incident fiber to the light entrance of the grating coupler, which can effectively improve the coupling efficiency and is suitable for wafer-level parameter testing;

Based on the same setting, the first outgoing optical coupler 400 and the second outgoing optical coupler 500 also use a grating coupler, and the first outgoing light beam I _out1 and the second outgoing light beam I _out2 are emitted from the light exit of the grating coupler, and are respectively set up subsequently The two outgoing optical fibers are received and enter the subsequent optical power measuring device to measure the optical power, wherein the optical power measuring device can use an optical power meter or a spectrometer.

In some embodiments, the optical beam splitter 200 can adopt a multimode interference coupler, a Y-type splitter or a directional coupler, and it has at least two split ends (the first split end 210 and the second split end 220 ), for splitting the incident beam I _in into two first split beams I _bs1 and second split beams I _bs2 with a fixed optical power ratio, wherein the optical power of the first split beam I _bs1 is P _bs1 , the optical power of the second split light beam I _bs2 is P _bs2 , the ratio of the two optical powers is K=P _bs1 /P _bs2 , in some preferred embodiments, K=1, that is, the optical beam splitter 200 uses power Ratio 0.5: 0.5 1×2 optical beam splitter, at this time P _out2 =P _bs2 =P _bs1 .

Embodiment two

This embodiment provides a method for measuring the effective emission length of the emission grating. This measurement method can calculate To obtain an accurate effective emission length to meet actual application conditions, the steps of the measurement method include steps S1) to S3).

Step S1), providing the measurement system 10 as described in Embodiment 1, the incident light beam I _in passes through the optical beam splitter 200 to form a first split light beam I _bs1 and a second split light beam I _bs2 , wherein the first The split beam I _bs1 and the second split beam I _bs2 have a fixed optical power ratio.

In this embodiment, first provide a light source, an incident optical fiber, an outgoing optical fiber, an optical power measurement device, and the measurement system 10 described in Embodiment 1. If the fixed splitting ratio of the prepared optical beam splitter 200 is known (the first split beam The optical power ratio between _bs1 and the second split light beam I _bs2 is, for example, 1:1), then it is no longer necessary to test the fixed split ratio of the optical beam splitter 200, otherwise, the following steps S11) to S2) need to be adopted. The fixed beam splitting ratio of the optical beam splitter 200 is obtained in the following way:

Step S11 ), connect the first light splitting end 210 directly to the first light output coupler 400 , and connect the second light splitting end 220 to the second light output coupler 500 .

Step S12), measuring the optical power of the light emitted by the first optical coupler 400 to obtain the optical power P _bs1 of the first split beam, measuring the optical power of the emitted light of the second optical coupler to obtain the optical power P _bs2 of the second split beam, and In this way, a fixed beam splitting ratio of the beam splitter 200 is obtained.

Step S2), connecting the first light splitting end 210 to the emission grating 300, and connecting the first optical output coupler 400 to the emission grating 300, and measuring the optical power P _out1 of the first outgoing light beam I _out1 ; Simultaneously connect the second optical splitter 220 to the second output optical coupler 500, and measure the optical power P _out2 of the second output light beam I _out2 .

In this embodiment, since the splitting ratio of the optical beam splitter 200 is fixed, the magnitude of the optical power P _out2 of the second outgoing beam is the same as the magnitude of the optical power P _bs2 of the second split beam.

Step S3), based on the ratio P _bs1 /P _bs2 of the optical power P _bs1 of the first split beam to the optical power P _bs2 of the second split beam, the optical power P _out1 of the first outgoing beam, the The optical power P _out2 of the second outgoing light beam and the length L of the emission grating are calculated to obtain the effective emission length L _neff of the emission grating.

In this embodiment, the test principle of the measurement system 10 described in Embodiment 1 can be obtained:

Wherein, the P _out1 represents the optical power of the first outgoing light beam, the P _out2 represents the optical power of the second outgoing light beam, and the P _bs1 represents the optical power of the first split light beam, The P _bs2 represents the optical power of the second split light beam, the L represents the length of the emission grating, and the L _neff represents the effective emission length of the emission grating.

In the case of known values of P _bs1 , P _bs2 , P _out1 , P _out2 and L, the effective emission length L _neff of the emission grating can be calculated from formula 1.

In summary, the measuring system and measuring 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 When the split beam enters the emission grating, its light intensity will decay exponentially along the direction of propagation, and it exits as the first outgoing beam, and the second split beam exits as the second outgoing beam without passing through the emission grating. The first outgoing beam and the second outgoing beam The effective emission length of the emission grating can be calculated by the optical power ratio of , which is in line with the actual application situation.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Anyone skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical ideas disclosed in the present invention should still be covered by the claims of the present invention.

Claims (9)

1. A measurement system of the effective emission length of the emission grating, connected with the emission grating, for measuring the effective emission length of the emission grating, it is characterized in that, the effective emission length measurement system of the emission grating includes: an optical coupler, An optical beam splitter, a first outgoing optical coupler and a second outgoing optical coupler; wherein, The incoming optical coupler is used to receive the incident light beam; The optical beam splitter is connected to the optical coupler and has a first splitting end and a second splitting end for splitting the incident beam into a first splitting beam and a second splitting beam, the The first split beam and the second split beam have a fixed optical power ratio, and the emission grating is connected to the first split end; The first output coupler is connected to the emission grating, and is used to output the first split light beam attenuated by the emission grating as a first output light beam; The second output coupler is connected to the second light splitting end, and is used to output the second split light beam into a second output light beam. 2 . The measuring system for the effective emission length of the emission grating according to claim 1 , wherein the optical input coupler, the first optical output coupler and the second optical output coupler are grating couplers. 3 . 3. The measurement system of emission grating effective emission length according to claim 1, is characterized in that, described measurement system also comprises: light source, incident optical fiber; Wherein, The light source is connected with the incident optical fiber, and the incident optical fiber is coupled and connected with the optical entrance coupler. 4. the measurement system of emission grating effective emission length according to claim 1, is characterized in that, described measurement system also comprises: the first outgoing optical fiber, the second outgoing optical fiber and optical power measuring device; Wherein, The first output optical fiber is coupled to the first output coupler; The second output optical fiber is coupled to the second output coupler; The optical power measurement device is connected to the first outgoing optical fiber and the second outgoing optical fiber, and measures 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 the emission grating according to claim 4, wherein the optical power measurement device is an optical power meter or a spectrometer. 6 . The system for measuring the effective emission length of an emission grating according to claim 1 , wherein 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 method for measuring comprises: Building the measurement system according to any one of claims 1-6, the incident beam is split by the optical beam splitter to form a first split beam and a second split beam, wherein the first split beam and the second split beam are The dichotomous beam has a fixed optical power ratio; Connect the first light splitting end to the emission grating, and connect the first outgoing light coupler to the emission grating to measure the optical power of the first outgoing light beam; simultaneously connect the second light splitting end to the emission grating The second outgoing optical coupler is connected to measure the optical power of the second outgoing light beam; The emission is calculated based on the optical power ratio of the first split beam to the second split beam, the optical power of the first outgoing beam, the optical power of the second outgoing beam, and the length of the emitting grating. Effective launch length of the grating. 8. The method for measuring the effective emission length of the emitting grating according to claim 7, wherein the method for obtaining the optical power ratio of the first split light beam and the second split light beam comprises: Connecting the first light splitting end to the first light output coupler, and connecting the second light splitting end to the second light output coupler; measuring the optical power of the light emitted by the first optical coupler to obtain the optical power of the first split beam, and measuring the optical power of the light emitted by the second optical coupler to obtain the optical power of the second split beam. 9. The method for measuring the effective emission length of the emission grating according to any one of claims 7-8, wherein the effective emission length _Lneff of the emission grating is calculated based on the following formula 1, Wherein, P _out1 represents the optical power of the first outgoing light beam, P _out2 represents the optical power of the second outgoing light beam, P _bs1 represents the optical power of the first split light beam, and P _bs2 represents the optical power of the first split light beam. The optical power of the second split light beam, L represents the length of the emission grating, and L _neff represents the effective emission length of the emission grating.