CN116577073A - System and method for measuring effective emission length of emission grating - Google Patents

System and method for measuring effective emission length of emission grating Download PDF

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Publication number
CN116577073A
CN116577073A CN202310625211.3A CN202310625211A CN116577073A CN 116577073 A CN116577073 A CN 116577073A CN 202310625211 A CN202310625211 A CN 202310625211A CN 116577073 A CN116577073 A CN 116577073A
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light
emission
coupler
grating
measuring
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王金玉
蔡艳
岳文成
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Shanghai Institute of Microsystem and Information Technology of CAS
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Shanghai Institute of Microsystem and Information Technology of CAS
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/02—Testing optical properties
    • G01M11/0242—Testing optical properties by measuring geometrical properties or aberrations
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/02—Testing optical properties
    • G01M11/0207—Details of measuring devices

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Geometry (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

The invention provides a measuring system and a measuring method for the effective emission length of an emission grating, wherein the measuring system comprises the following components: an in-coupling optical coupler, an optical splitter, a first out-coupling optical coupler, and a second out-coupling optical coupler; wherein the light in-coupling device is used for receiving incident light beams; the light beam splitter is connected with the light inlet coupler and provided with a first light splitting end and a second light splitting end, the first light splitting end is connected with the emission grating, the first light outlet coupler is connected with the emission grating, and the first light splitting light beam attenuated by the emission grating is emitted to be a first emergent light beam; the second light-out coupler is connected with the second light-splitting end and outputs a second emergent light beam. The system and the method for measuring the effective emission length of the emission grating can solve the problems that the effective emission length of the prepared emission grating is inconsistent with the grating length obtained by simulation design and the accurate effective emission length of the emission grating cannot be obtained due to process errors.

Description

System and method for measuring effective emission length of emission grating
Technical Field
The invention relates to the field of laser radars, in particular to a measuring system and a measuring method for the effective emission length of an emission grating.
Background
The silicon-based optical phased array can realize the scanning of any position and is one of the important schemes for realizing the all-solid-state laser radar; the common silicon-based optical phased array transmits light beams through a transmitting unit to realize beam scanning, and how to realize a large scanning range and high resolution of the phased array is a hot spot of current research.
The resolution of the optical phased array is determined by the aperture of the transmit array, with the effective transmit length of the transmit grating determining the resolution of the longitudinal scan of the phased array, and therefore increasing the effective transmit length of the transmit grating is an effective way to increase the resolution of the optical phased array beam scan.
Among them, a great deal of research has been carried out on simulation methods of the emission grating, but due to etching depth errors, mask alignment errors, rough waveguide sidewalls, etc. caused by process preparation, the actual effective emission length of the emission grating is inconsistent with the simulation results, and thus a detection method for testing the effective emission length of the emission grating is needed.
Disclosure of Invention
In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a system and a method for measuring an effective emission length of an emission grating, which are used for solving the problem that the effective emission length of a prepared emission grating is inconsistent with a grating length obtained by a simulation design due to a process error, and an accurate effective emission length of the emission grating cannot be obtained correctly.
To achieve the above and other related objects, the present invention provides a system for measuring an effective emission length of an emission grating, connected to the emission grating, for measuring the effective emission length of the emission grating, the system comprising: an in-coupling optical coupler, an optical splitter, a first out-coupling optical coupler, and a second out-coupling optical coupler; wherein,,
the light in-coupling device is used for receiving incident light beams;
the optical beam splitter is connected with the light inlet coupler, provided with a first light splitting end and a second light splitting end, and used for splitting the incident light beam into a first light splitting beam and a second light splitting beam, wherein the first light splitting beam and the second light splitting beam have fixed light power proportion, and the first light splitting end is connected with the emission grating;
the first light-out coupler is connected with the emission grating and is used for emitting the first split light beam attenuated by the emission grating into a first emitted light beam;
the second light-out coupler is connected with the second light splitting end and is used for emitting the second light splitting beam into a second emergent beam.
Optionally, the in-coupling coupler, the first out-coupling coupler and the second out-coupling coupler adopt grating couplers.
Optionally, the measurement system further comprises: a light source, an incident optical fiber; the light source is connected with the incident optical fiber, and the incident optical fiber is coupled and connected with the light in-coupling coupler.
Optionally, the measurement system further comprises: the first emergent optical fiber, the second emergent optical fiber and the optical power measuring device; wherein,,
the first emergent optical fiber is coupled with the first emergent optical coupler;
the second emergent optical fiber is coupled with the second emergent optical coupler;
the optical power measuring device is connected with the first emergent optical fiber and the second emergent optical fiber and is used for measuring the optical power of the first emergent light beam and the second emergent 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 invention also provides a measuring method of the effective emission length of the emission grating, which is characterized by comprising the following steps:
constructing the measuring system according to any one of the preceding claims, and splitting an incident beam by the 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 optical power ratio;
connecting the first light splitting end with the emission grating, connecting the first light emergent coupler with the emission grating, and measuring the optical power of a first emergent light beam; simultaneously connecting the second light splitting end with the second light emergent coupler, and measuring the optical power of a second emergent light beam;
calculating the effective emission length of the emission grating based on the light power ratio of the first beam splitter to the second beam splitter, the light power of the first beam splitter, the light power of the second beam splitter and the length of the emission 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 with the first light out coupler, and connecting the second light splitting end with the second light out coupler;
and measuring the optical power of the light emitted by the first light-emitting coupler to obtain the optical power of the first light-splitting beam, and measuring the optical power of the light emitted by the second light-emitting coupler to obtain the optical power of the second light-splitting beam.
Alternatively, the effective emission length L of the emission grating is calculated based on the following equation 1 neff ，
Wherein P is out1 Represented as the optical power of the first outgoing beam, P out2 Represented as the optical power of the second outgoing beam, P bs1 Represented as the optical power, P, of the first split beam bs2 Expressed as the optical power of the second split beam, L expressed as the length of the emission grating, L neff Represented as the effective emission length of the emission grating.
As described above, the measuring system and the measuring method for the effective emission length of the emission grating are provided with the optical beam splitter, the incident light is split into the first split light beam and the second split light beam with fixed light power ratio, the first split light beam is emitted into the emission grating, the light intensity of the first split light beam is exponentially attenuated along the propagation direction and is emitted into the first emission light beam, the second split light beam is emitted into the second emission light beam without passing through the emission grating, the effective emission length of the emission grating can be calculated by the light power ratio of the first emission light beam and the second emission light beam, and the measuring system and the measuring method accord with practical application conditions.
Drawings
Fig. 1 is a schematic structural diagram of an effective emission length measurement system of an emission grating according to the present invention.
Fig. 2 is a schematic diagram of a structure for measuring the ratio of the optical powers of the first split beam and the second split beam according to the present invention.
Description of the component reference numerals
10. System for measuring effective emission length of emission grating
100. Light in-coupling coupler
200. Light beam splitter
210. First spectroscopic terminal
220. A second light-splitting end
300. Emission grating
400. First light-out coupler
500. Second light-out coupler
Detailed Description
Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention.
Referring to fig. 1 to 2, the schematic drawings provided in the present embodiment are only for illustrating the basic concept of the present invention, and only the components related to the present invention are shown in the drawings, rather than the number, shape and size of the components in actual implementation, and the form, number and proportion of each component in actual implementation may be arbitrarily changed, and the layout of the components may be more complex.
Example 1
The present embodiment provides an effective emission length measurement system 10 of an emission grating, which is connected to an emission grating 300 for measuring the effective emission length of the emission grating 300, and as shown in fig. 1, the measurement system 10 includes an in-coupling coupler 100, an optical splitter 200, a first out-coupling coupler 400, and a second out-coupling coupler 500.
In this embodiment, the length L of the emission grating 300 is preset by using an optical simulation method before designing and manufacturing, and the optical power is P according to the simulation preset bs1 Is a first outgoing beam I of (1) out1 Incident on the emission grating 300 and emitted from the emission grating 300 (the optical path length of the beam is L), the emitted light power P out1 Will decay to P bs1 *e -2 The method comprises the steps of carrying out a first treatment on the surface of the However, due to the etching depth error, mask alignment error, waveguide sidewall roughness, etc. caused by the process preparation, the first emergent beam I will be caused out1 The optical power of the emission grating 300 when emitted from the emission grating is not equal to P bs1 *e -2 (typically, the ratio P bs1 *e -2 Small), it is therefore necessary to obtain a first outgoing light beam I by the measuring system according to the present embodiment out1 After incidence on the emission grating 300, the optical power decays to P bs1 *e -2 I.e. the actual effective emission length L of the emission grating 300 is required to be obtained neff (effective emission length is defined as e when the optical power of incident light decays to an initial value -2 Length at) of the joint). The test principle is as follows:
considering the emission grating 300 as a grating with a uniform diffraction structure, the perturbation intensity is a constant α 0 The power of one beam of light is P bs1 The relation of the travel x of the beam along the emission grating with the remaining optical power P (x) at the x position can be expressed as:
wherein, assume that at x=l neff Can be positioned to make the first emergent beam I out1 Is attenuated to P bs1 *e -2 Thus, P (x) =P 0 *e -2 Substitution into formula 2 yields:
L neff ＝1/α 0 [ formula 3 ]]；
As shown in fig. 2, the first spectroscopic beam I can be measured by connecting the first spectroscopic end 210 to the first optical coupler 400 and connecting the second spectroscopic end 220 to the second optical coupler 500 bs1 Is set to be equal to the optical power P of (2) bs1 And a second split beam I bs2 Is set to be equal to the optical power P of (2) bs2 。
Meanwhile, as shown in fig. 2, the first light splitting end 210 is connected to the light incident end of the emission grating 300, the light emitting 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, so that the first outgoing light beam I can be measured out1 Is set to be equal to the optical power P of (2) out1 And a second emergent beam I out2 Is set to be equal to the optical power P of (2) out2 Wherein P is out2 ＝P bs2 And it can be seen that the number of the components,
substituting formula 3 into formula 4 yields the following formula 1:
the effective emission length L of the emission grating 300 can be calculated from 1 neff To conform to the actual application of the emission grating 300.
In some embodiments, the system 10 for measuring the effective emission length of the emission grating is integrated in a silicon optical device, and the in-coupling coupler 100 may be a grating coupler, and the incident light beam I emitted by a light source (laser) outside the silicon optical device in The light outlet of the incident optical fiber is incident to the light inlet of the grating coupler, so that the coupling efficiency can be effectively improved, and the method is suitable for wafer-level parameter testing;
based on the same arrangement, the first and second optocouplers 400 and 500 also adoptGrating coupler for first outgoing beam I out1 Second outgoing light beam I out2 The light is emitted from the light outlet of the grating coupler, is received by two light emitting fibers which are respectively arranged subsequently and enters a subsequent optical power measuring device for measuring the optical power, wherein the optical power measuring device can adopt an optical power meter or a spectrometer.
In some embodiments, the optical splitter 200 may employ a multimode interference coupler, a Y-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 Splitting into two first split beams I with fixed optical power ratio bs1 Second split light beam I bs2 Wherein the first beam I bs1 Is of optical power P bs1 Second split light beam I bs2 Is of optical power P bs2 The ratio of the two optical powers is K=P bs1 /P bs2 In some preferred embodiments, k=1, i.e. the beam splitter 200 employs a power ratio of 0.5:0.5 1X 2 beam splitter, at which point P out2 ＝P bs2 ＝P bs1 。
Example two
The embodiment provides a method for measuring the effective emission length of an emission grating, which can calculate and obtain the accurate effective emission length to meet the actual application condition when the emission grating length is inconsistent with the actual effective emission length due to the transmission loss caused by the factors of a preparation process (such as the roughness of the side wall of a waveguide, and the like), and the steps of the measuring method comprise the steps S1) to S3).
Step S1) providing a measurement system 10 as described in embodiment one, incident light beam I in Beam-forming a first split beam I by the beam splitter 200 bs1 Second split light beam I bs2 Wherein the first beam I bs1 And the second split beam I bs2 With a fixed optical power ratio.
In this embodiment, a light source, an incident optical fiber, an emergent optical fiber, an optical power measuring device, and the measuring system 10 according to embodiment one are provided first, if the prepared light is knownFixed split ratio of beam splitter 200 (first split beam I bs1 And a second split beam I bs2 For example, 1: 1) The fixed splitting ratio of the optical splitter 200 is not required to be tested, otherwise, the fixed splitting ratio of the optical splitter 200 is required to be obtained by adopting the following steps S11) to S2):
step S11), the first optical splitter 210 is directly connected to the first optical out-coupler 400, and the second optical splitter 220 is connected to the second optical out-coupler 500.
Step S12), measuring the optical power of the light emitted from the first light-emitting coupler 400 to obtain the optical power P of the first split beam bs1 Measuring the optical power of the emergent light of the second light emergent coupler to obtain the optical power P of the second split beam bs2 And thus a fixed split ratio of the optical beam splitter 200 is obtained.
Step S2), connecting the first spectroscopic end 210 with the emission grating 300, and connecting the first light-out coupler 400 with the emission grating 300, and measuring a first outgoing light beam I out1 Is set to be equal to the optical power P of (2) out1 The method comprises the steps of carrying out a first treatment on the surface of the Simultaneously connecting the second light splitting end 220 with the second light out-coupling device 500 to measure a second outgoing light beam I out2 Is set to be equal to the optical power P of (2) out2 。
In the present embodiment, since the beam splitting ratio of the beam splitter 200 is fixed, the optical power P of the second outgoing beam out2 The size of the second beam of light and the optical power P of the second beam of light bs2 Is the same size.
Step S3), based on the optical power P of the first split beam bs1 Optical power P with the second split beam bs2 Ratio P of (2) bs1 /P bs2 The optical power P of the first emergent beam out1 The optical power P of the second emergent beam out2 And calculating the length L of the emission grating to obtain the effective emission length L of the emission grating neff 。
In this embodiment, the test principle of the measurement system 10 according to the first embodiment can be obtained:
wherein the P is out1 Represented as the optical power of the first outgoing beam, the P out2 Represented as the optical power of the second outgoing beam, the P bs1 Represented as the optical power of the first split beam, the P bs2 Expressed as the optical power of the second split beam, the L expressed as the length of the emission grating, the L neff Represented as the effective emission length of the emission grating.
At a known P bs1 、P bs2 、P out1 、P out2 And L, the effective emission length L of the emission grating can be calculated by the formula 1 neff 。
In summary, the measuring system and the measuring method for the effective emission length of the emission grating of the present invention are provided with the optical beam splitter, the incident light is split into the first split beam and the second split beam with a fixed optical power ratio, the first split beam is emitted into the emission grating, the light intensity of the first split beam is exponentially attenuated along the propagation direction, the first split beam is emitted as the first emission beam, the second split beam is not emitted as the second emission beam through the emission grating, the effective emission length of the emission grating can be calculated from the optical power ratio of the first emission beam and the second emission beam, and the present invention accords with practical application conditions.
The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims (9)

1. A system for measuring the effective emission length of an emission grating, coupled to the emission grating, for measuring the effective emission length of the emission grating, the system comprising: an in-coupling optical coupler, an optical splitter, a first out-coupling optical coupler, and a second out-coupling optical coupler; wherein,,
the light in-coupling device is used for receiving incident light beams;
the optical beam splitter is connected with the light inlet coupler, provided with a first light splitting end and a second light splitting end and used for splitting the incident light beam into a first light splitting beam and a second light splitting beam, the first light splitting beam and the second light splitting beam have fixed light power proportion, and the emission grating is connected with the first light splitting end;
the first light-out coupler is connected with the emission grating and is used for emitting the first split light beam attenuated by the emission grating into a first emitted light beam;
the second light-out coupler is connected with the second light splitting end and is used for emitting the second light splitting beam into a second emergent beam.
2. The system of claim 1, wherein the in-coupling coupler, the first out-coupling coupler, and the second out-coupling coupler are grating couplers.
3. The system for measuring the effective emission length of an emission grating of claim 1, further comprising: a light source, an 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 light in-coupling coupler.
4. The system for measuring the effective emission length of an emission grating of claim 1, further comprising: the first emergent optical fiber, the second emergent optical fiber and the optical power measuring device; wherein,,
the first emergent optical fiber is coupled with the first emergent optical coupler;
the second emergent optical fiber is coupled with the second emergent optical coupler;
the optical power measuring device is connected with the first emergent optical fiber and the second emergent optical fiber and is used for measuring the optical power of the first emergent light beam and the second emergent light beam.
5. The system for measuring the effective emission length of an emission grating according to claim 4, wherein the optical power measuring 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, the method comprising:
constructing the measuring system according to any one of claims 1-6, wherein an incident beam is split by the beam splitter to form a first split beam and a second split beam, and the first split beam and the second split beam have a fixed optical power ratio;
connecting the first light splitting end with the emission grating, connecting the first light emergent coupler with the emission grating, and measuring the optical power of a first emergent light beam; simultaneously connecting the second light splitting end with the second light emergent coupler, and measuring the optical power of a second emergent light beam;
and calculating the effective emission length of the emission grating based on the light power ratio of the first beam splitter to the second beam splitter, the light power of the first emergent beam, the light power of the second emergent beam and the length of the emission grating.
8. The method of measuring an effective emission length of an emission grating according to claim 7, wherein the method of obtaining an optical power ratio of the first split beam to the second split beam comprises:
connecting the first light splitting end with the first light out coupler, and connecting the second light splitting end with the second light out coupler;
and measuring the optical power of the light emitted by the first light-emitting coupler to obtain the optical power of the first light-splitting beam, and measuring the optical power of the light emitted by the second light-emitting coupler to obtain the optical power of the second light-splitting beam.
9. The method for measuring the effective emission length of an emission grating according to any one of claims 7 to 8, wherein the effective emission length L of the emission grating is calculated based on the following equation 1 neff ，
Wherein P is out1 Represented as the optical power of the first outgoing beam, P out2 Represented as the optical power of the second outgoing beam, P bs1 Represented as the optical power, P, of the first split beam bs2 Expressed as the optical power of the second split beam, L expressed as the length of the emission grating, L neff Represented as the effective emission length of the emission grating.
CN202310625211.3A 2023-05-30 2023-05-30 System and method for measuring effective emission length of emission grating Pending CN116577073A (en)

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