Inspection device and inspection method

Abstract

To properly inspect a photonic integrated circuit by acquiring information of light output from the photonic integrated circuit.SOLUTION: An inspection device 1 includes: a stage 10 which holds a PIC 100; a PIC controller 20 which controls an operation of the PIC 100; an LRG filter 61 which has transmission characteristics in which transmittance linearly changes in a prescribed wavelength region and transmits or reflects light guided by a waveguide 108 and output from at least one light output part 102 on the basis of the transmission characteristics; a camera 62 which images the light transmitted through the LRG filter 61, to output a transmission image and images the light arriving without through the LRG filter 61, to output a total-light-quantity image; and a computer 70 which executes first processing for deriving wavelength information of the light output from the light output part 102 on the basis of the transmission image and the total-light-quantity image.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an inspection apparatus and an inspection method. [Background technology]

[0002] In recent years, the development of photonic integrated circuits (PIC: Photonic IC) has progressed. A photonic integrated circuit is a device that integrates various optical functions and transmits information signals by light. As a method for inspecting a photonic integrated circuit, a method is known in which infrared light scattered by a defect in a waveguide in the photonic integrated circuit is captured, and the captured image is displayed on a display to grasp the spatial position of the defect (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-58070 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned inspection method, although the spatial position of the defect can be grasped from the captured image, it is not possible to obtain information (e.g., wavelength information) about the light output from the photonic integrated circuit, which may make it difficult to perform an appropriate inspection of the photonic integrated circuit.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and relates to an inspection device and an inspection method capable of appropriately inspecting a photonic integrated circuit by acquiring information on light output from the photonic integrated circuit. [Means for solving the problem]

[0006] An inspection device according to one embodiment of the present disclosure is [1] "an inspection device for inspecting a photonic integrated circuit having at least one optical output unit and a waveguide, comprising: a stage for holding the photonic integrated circuit; a control unit for controlling the operation of the photonic integrated circuit; an optical filter having transmission characteristics in which the transmittance changes linearly in a predetermined wavelength range, and transmitting or reflecting light guided by the waveguide and output from the at least one optical output unit based on the transmission characteristics; an imaging unit that images the light transmitted or reflected by the optical filter and outputs first image data, and that images the light output from the optical output unit that reaches the optical output unit without passing through the optical filter and outputs second image data; and an analysis unit that performs a first process to derive wavelength information of the light output from the optical output unit based on the first image data and the second image data."

[0007] In the inspection device according to one aspect of the present disclosure, the light output from the light output unit of the photonic integrated circuit is transmitted or reflected by the optical filter according to the wavelength. Then, based on the first image data of the light transmitted or reflected by the optical filter and the second image data of the light arriving without passing through the optical filter, the wavelength information of the light output from the light output unit is derived. In this way, in the inspection device according to one aspect of the present disclosure, the optical filter is used to transmit or reflect the light according to the wavelength, so that the first image data is image data according to the wavelength of the light. Also, since the first image data is image data of the light transmitted or reflected by the optical filter and the second image data is image data of the light arriving without passing through the optical filter, information of the light transmitted through the optical filter and the light reflected by the optical filter can be obtained from these image data. In this way, by obtaining information of the light transmitted or reflected according to the wavelength, the wavelength information of the light can be obtained with high accuracy. As described above, according to the inspection device according to one aspect of the present disclosure, information of the light output from the photonic integrated circuit (specifically, wavelength information) can be obtained, and as a result, the photonic integrated circuit can be appropriately inspected using the wavelength information.

[0008] An inspection device according to one aspect of the present disclosure may be [2] "the inspection device according to [1], in which the photonic integrated circuit has a plurality of optical output units, and the optical filter transmits or reflects each of the lights output from the plurality of optical output units based on the transmission characteristics." With such a configuration, wavelength information of the light from the plurality of optical output units provided at spatially different positions can be acquired collectively, and the photonic integrated circuit can be inspected more quickly and appropriately.

[0009] The inspection device according to one aspect of the present disclosure may be the inspection device according to [1] or [2], in which the imaging unit has an image sensor that images the light transmitted through or reflected by the optical filter and also images the light output from the light output unit that reaches the inspection device without passing through the optical filter. Such an image sensor can appropriately image the desired light.

[0010] The inspection device according to one aspect of the present disclosure may be [4] "the inspection device according to any one of [1] to [3], further comprising a switching unit configured to be able to switch between a state in which an optical filter is provided and a state in which an optical filter is not provided in an optical path between the light output unit and the imaging unit." With such a configuration, both the first image data and the second image data described above can be appropriately acquired while switching between the presence and absence of the optical filter.

[0011] The inspection device according to one aspect of the present disclosure may be the inspection device according to any one of [1] to [4], in which the imaging unit has an optical branching unit that branches the light output from the optical output unit into a first branched optical path and a second branched optical path, a first image sensor arranged on the first branched optical path, and a second image sensor arranged on the second branched optical path, and the optical filter is arranged between the optical branching unit on the first branched optical path and the first image sensor, the first image sensor images the light transmitted through or reflected by the optical filter and outputs the first image data, and the second image sensor images the light output from the optical output unit that has reached the optical output unit without passing through the optical filter and outputs the second image data. According to this configuration, the optical branching unit branches the light into the first branched optical path and the second branched optical path, so that the first image data and the second image data can be acquired simultaneously, and the inspection can be performed efficiently.

[0012] An inspection device according to one aspect of the present disclosure may be [6] "the inspection device according to any one of [1] to [5], in which the control unit controls the temperature of at least a part of the photonic integrated circuit." By controlling the temperature of the photonic integrated circuit in this manner, the characteristics of the waveguide of the photonic integrated circuit are controlled, and for example, the wavelength of the light output from the light output unit can be adjusted. This makes it possible to appropriately inspect the photonic integrated circuit while easily changing the conditions of the wavelength of the light.

[0013] An inspection device according to one aspect of the present disclosure may be [7] "the inspection device according to any one of [1] to [6], in which the photonic integrated circuit has at least one optical input section, and the optical output section outputs light input from the optical input section and guided by the waveguide." With such a configuration, it is possible to appropriately obtain wavelength information about light input from the optical input section of the photonic integrated circuit, passed through the waveguide, and output from the optical output section.

[0014] The inspection device according to one aspect of the present disclosure may be [8] "the inspection device according to any one of [1] to [7], further comprising a first optical scanner unit that performs an optical scan on a first region in a photonic integrated circuit in which an optical input unit is formed and detects light related to the optical scan, and the analysis unit further executes a second process that identifies in advance the position of the optical input unit to which light is input when the first process is performed, and identifies the position of the optical input unit based on the intensity of light detected by the first optical scanner unit in the second process." With this configuration, the position of the optical input unit can be identified based on the difference in the intensity of light, and the subsequent first process (process of deriving wavelength information of the light output from the optical output unit) can be appropriately performed.

[0015] The inspection device according to one aspect of the present disclosure may be [9] "the inspection device according to any one of [1] to [8], further comprising a second optical scanner unit that performs an optical scan on a second region in the photonic integrated circuit where an optical output unit is formed and detects light related to the optical scan, and the analysis unit further executes a third process for identifying in advance the position of the optical output unit that outputs light when the first process is performed, and in the third process, identifies the position of the optical output unit based on the intensity of light detected by the second optical scanner unit." With such a configuration, the position of the optical output unit can be identified based on the difference in the intensity of light, and the subsequent first process (process for deriving wavelength information of the light output from the optical output unit) can be appropriately performed.

[0016] The inspection device according to one aspect of the present disclosure may be

[10] "the inspection device according to any one of [1] to [9], in which the analysis unit, in the first process, derives a transmission intensity, which is the intensity of light transmitted through the optical filter, from the first image data, and derives a total intensity of light output from the light output unit from the second image data, derives a reflection intensity, which is the intensity of light reflected by the optical filter, based on the transmission intensity and the total intensity, and derives wavelength information based on the transmission intensity and the reflection intensity." Since light is transmitted or reflected in the optical filter according to the wavelength, it is possible to derive wavelength information with high accuracy from information on the transmission intensity (amount of transmitted light) and the reflection intensity (amount of reflected light).

[0017] The inspection device according to one aspect of the present disclosure may be

[11] "the inspection device according to any one of [1] to [9], in which the analysis unit, in the first process, derives a reflection intensity, which is the intensity of light reflected by the optical filter, from the first image data, and derives a total intensity of light output from the light output unit from the second image data, derives a transmission intensity, which is the intensity of light transmitted through the optical filter, based on the reflection intensity and the total intensity, and derives wavelength information based on the transmission intensity and reflection intensity." Since light is transmitted or reflected in the optical filter according to the wavelength, it is possible to derive wavelength information with high accuracy from information on the transmission intensity (amount of transmitted light) and the reflection intensity (amount of reflected light).

[0018] The inspection device according to one aspect of the present disclosure may be the inspection device according to

[10] or

[11] , in which the analysis unit derives a difference value between the transmitted intensity and the reflected intensity, and derives the wavelength information based on the difference value. By deriving the wavelength information from the difference value between the transmitted intensity and the reflected intensity, the wavelength information can be derived with high accuracy.

[0019] The inspection device according to one aspect of the present disclosure may be the inspection device according to any one of [1] to

[12] , wherein

[13] "the wavelength information is information indicating the centroid wavelength of the light output from the light output unit. This makes it possible to appropriately derive the wavelength information.

[0020] The inspection device according to one aspect of the present disclosure may be the inspection device according to any one of [1] to

[13] , wherein the analysis unit further performs a fourth process of creating a table showing the relationship between the wavelength information and the temperature control of the photonic integrated circuit by associating the wavelength information derived in the first process with information related to the temperature control of the photonic integrated circuit by the control unit when the wavelength information was derived. With such a configuration, it is possible to create a table of temperature control when adjusting the wavelength of the photonic integrated circuit, making it easier to control the photonic integrated circuit.

[0021] An inspection method according to one aspect of the present disclosure is

[15] "an inspection method for inspecting a photonic integrated circuit having at least one optical output unit and a waveguide, the inspection method including: controlling the operation of the photonic integrated circuit; transmitting or reflecting light guided by the waveguide and output from the at least one optical output unit based on the transmission characteristics of an optical filter having a transmission characteristic in which the transmittance changes linearly in a predetermined wavelength range; capturing an image of the light transmitted or reflected by the optical filter and outputting first image data; capturing an image of the light output from the optical output unit that reaches the optical output unit without passing through the optical filter and outputting second image data; and deriving wavelength information of the light output from the optical output unit based on the first image data and the second image data." Effect of the Invention

[0022] According to the present disclosure, by acquiring information on the light output from a photonic integrated circuit, the photonic integrated circuit can be appropriately inspected. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is a side view that diagrammatically illustrates an inspection device according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a plan view showing a schematic diagram of the PIC. [Diagram 3] FIG. 3(a) is a side view of the input end face side of the PIC, and FIG. 3(b) is a side view of the output end face side of the PIC. [Figure 4] FIG. 4 is a diagram illustrating the spectrum of light and the characteristics of an LRG filter. [Diagram 5] FIG. 5 is a side view showing details of the inspection device shown in FIG. [Figure 6] 6(a) to (c) are diagrams illustrating the setting step. [Figure 7] FIG. 7 is a diagram illustrating the setting process. [Figure 8] FIG. 8 is a diagram illustrating a process for roughly identifying the position of the light input portion. [Figure 9] FIG. 9 is a diagram for explaining a process for roughly identifying the position of the light input portion. [Figure 10] FIG. 10 is a diagram for explaining a process for roughly identifying the position of the light input portion. [Figure 11] FIG. 11 is a diagram illustrating a process for roughly identifying the position of the light output unit. [Figure 12] FIG. 12 is a diagram illustrating a process for roughly identifying the position of the light output unit. [Figure 13] FIG. 13 is a diagram illustrating a process for roughly identifying the position of the light output unit. [Figure 14] FIG. 14 is a diagram illustrating a process of determining the position of the optical input section with high accuracy and a process of determining the position of the optical output section with high accuracy. [Figure 15] FIG. 15 is a diagram illustrating a process for identifying the position of the light input portion with high accuracy. [Figure 16] FIG. 16 is a diagram illustrating a process for identifying the position of the light output unit with high accuracy. [Figure 17] FIG. 17 is a diagram for explaining the process of deriving wavelength information. [Figure 18] FIG. 18 is a diagram for explaining the process of deriving wavelength information. [Figure 19] FIG. 19 is a diagram for explaining the process of deriving wavelength information. [Figure 20] FIG. 20 is a diagram showing an example of the relationship between the heater input power and the wavelength shift amount. [Figure 21] FIG. 21 is a flow chart of the inspection method. [Figure 22] FIG. 22 is a side view that illustrates a schematic diagram of an inspection device according to the second embodiment of the present disclosure. [Diagram 23] FIG. 23 is a diagram illustrating a process for determining the position of the grating with high accuracy. [Figure 24] FIG. 24 is a diagram illustrating a process for determining the position of the grating with high accuracy. [Diagram 25] FIG. 25 is a diagram for explaining the process of deriving wavelength information. [Figure 26] FIG. 26 is a diagram illustrating a process of deriving wavelength information in the third embodiment of the present disclosure. [Figure 27] FIG. 27 is a diagram for explaining the process of deriving wavelength information. [Figure 28] 28(a) and (b) are diagrams illustrating an imaging mechanism according to a first modified example. [Figure 29] 29(a) and (b) are diagrams illustrating an imaging mechanism according to a second modified example. [Diagram 30] 30(a) and (b) are diagrams illustrating an imaging mechanism according to a third modified example. [Diagram 31] FIG. 31 is a diagram illustrating an imaging mechanism according to a fourth modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, the embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are denoted by the same reference numerals, and duplicated explanations will be omitted.

[0025] [First embodiment] FIG. 1 is a side view showing a schematic diagram of an inspection device 1 according to a first embodiment. The inspection device 1 is a device for inspecting a photonic integrated circuit (PIC: Photonic IC) 100. The PIC100 is a circuit in which a plurality of photonics components such as a waveguide, a laser element, a modulator, and a detector are integrated on one chip. The PIC100 is superior in speed, wideband, and power efficiency compared to conventional integrated circuits such as silicon ICs. In addition, the inspection here may include not only checking whether the PIC100 has any abnormality (defect) but also generating information required for controlling the PIC100, for example. The inspection device 1 detects light output from the PIC100, derives wavelength information of the light, and inspects the PIC100 using the wavelength information. By deriving wavelength information of the light output from PIC100, it is possible to check whether light of the desired wavelength is being output (channel accuracy, stability of optical output), whether there are any problems with the electrical or optical connection of the laser element in PIC100, whether there are any defects in the waveguide in PIC100 (presence or absence of light leakage, degree of light leakage), whether the optical transmission characteristics of the waveguide (wavelength-transmittance) are appropriate, etc.

[0026] The inspection device 1 transmits or reflects the light from the PIC100 according to the wavelength component, and captures the transmitted light or reflected light to obtain an image (first image data). The inspection device 1 also captures the light output from the PIC100 to obtain an image (second image data). Then, the inspection device 1 derives wavelength information of the light output from the PIC100 based on the above two images (details will be described later).

[0027] As shown in FIG. 1, the inspection device 1 includes a stage 10, a PIC controller 20 (control unit), a probe card 30, a mirror 40, a condenser lens 50, an imaging mechanism 60, and a computer 70 (analysis unit).

[0028] The PIC100 is placed and held on the stage 10. The stage 10 may be an XYZ stage configured to be able to move the PIC100 in XYZ directions (front-back, left-right, and up-down directions). The position of the PIC100 may be adjusted by the XYZ stage, and focus adjustment may be performed.

[0029] FIG. 2 is a plan view showing the PIC100. FIG. 3(a) is a side view of the input end face 100a side of the PIC100, and FIG. 3(b) is a side view of the output end face 100b side of the PIC100. The PIC100 is a device that integrates various optical functions and transmits information signals by light. As shown in FIG. 2, the PIC100 is configured to include various elements. In the example shown in FIG. 2, the PIC100 includes an optical input section 101, an optical output section 102, a grating 103, a laser element 104, an input coupler 105, an optical modulator 106, an optical coupler 107, a waveguide 108, photodiodes 109 and 112, an optical ring resonator circuit 110, a photonic crystal 111, and the like. The PIC100 has at least one optical output section and a waveguide.

[0030] The optical input section 101 is a section where light is input from the outside of the PIC100 to the inside of the PIC100. As shown in Fig. 3(a), the optical input section 101 is formed on an input end face 100a which is one side face of the PIC100. Although only one optical input section 101 is shown in Fig. 3(a), a plurality of optical input sections 101 are formed on the input end face 100a. For example, in a practical state after inspection, an optical cable is connected to the optical input section 101.

[0031] The optical output unit 102 is a part that outputs light to the outside of the PIC100. As shown in FIG. 3(b), the optical output unit 102 is formed on the other end face, that is, the output end face 100b, of the PIC100. Although only one optical output unit 102 is shown in FIG. 3(b), a plurality of optical output units 102 are formed on the output end face 100b. For example, in a practical state after inspection, an optical cable is connected to the optical output unit 102. The optical output unit 102 may output light that is input from the optical input unit 101 and guided by the waveguide 108 to the outside of the PIC100.

[0032] Grating 103 is disposed on the front surface (top surface) of PIC 100, and functions as an optical output section that outputs light upward (to the outside of PIC 100). Laser element 104 is a light source that emits laser light into PIC 100. The light emitted from laser element 104 passes through input coupler 105 and optical modulator 106, reaches optical coupler 107, and is guided by waveguide 108.

[0033] Photodiodes 109 and 112 are photodetectors provided inside PIC 100. Optical ring resonator circuit 110 is a circuit that sets a resonant wavelength. Photonic crystal 111 is a structure in which the refractive index changes periodically, and is a structure that confines light in a small region and manipulates the light. Note that PIC 100 may include various elements in addition to the above-mentioned configurations (elements). PIC 100 may be equipped with a microheater (not shown) on each element such as optical ring resonator circuit 110 or an optical modulator. The microheater is configured to change the refractive index of a waveguide that constitutes each element such as optical ring resonator circuit 110 or an optical modulator, and control the resonant wavelength of the guided light.

[0034] Returning to FIG. 1, the PIC controller 20 is a control unit for controlling the operation of each element in the PIC 100, which is the object of inspection. The PIC controller 20 is electrically connected to the PIC 100 via the probe card 30. The PIC controller 20 supplies power to a light emitting element (such as a laser element 104 or an amplifier element). The PIC controller 20 supplies a modulation signal to an optical modulator (such as an amplifier type modulator, an electroabsorption type modulator, a depletion layer type modulator, or a ring modulator). The modulation signal here is, for example, a signal related to modulation of light intensity or a signal related to switching of an optical switch. The PIC controller 20 supplies power to a microheater to control the temperature of at least a part of the PIC 100. This controls the refractive index of the light guided in the waveguide 108 and the resonator length in the optical ring resonator circuit 110. The PIC controller 20 supplies power to the photodiodes 109 and 112. The PIC controller 20 measures the temperature of the PIC 100. The temperature measurement may be performed by measuring the resistance of a resistive element, or by measuring the voltage of a thermocouple. The PIC controller 20 may control the IC part mounted on the PIC 100, or may measure the wavelength of emitted light. These functions may be performed by an external device other than the PIC controller 20.

[0035] The mirror 40 is a mirror that reflects the light from the PIC 100 in the direction of the condenser lens 50. The condenser lens 50 is, for example, an objective lens, and is a lens that condenses the light in the direction of the imaging mechanism 60.

[0036] The imaging mechanism 60 includes an LRG (Linear Reflectance Gradient on the wavelength axis) filter 61 (optical filter), a camera 62 (image sensor, imaging unit), and a switching unit 63.

[0037] The LRG filter 61 is a filter made of a special optical material, and separates the light from the PIC 100 by transmitting or reflecting it according to the wavelength. The LRG filter 61 has a transmission characteristic in which the transmittance changes linearly in a predetermined wavelength range, and transmits or reflects the light guided by the waveguide 108 and output from the optical output unit 102 based on the transmission characteristic.

[0038] FIG. 4 is a diagram for explaining the spectrum of light and the characteristics of the LRG filter 61. In FIG. 4, the horizontal axis indicates the wavelength, and the vertical axis indicates the spectrum intensity (in the case of the spectrum of light) and the transmittance (in the case of the LRG filter 61). As shown in the characteristic X4 of the LRG filter 61 in FIG. 4, in the LRG filter 61, the transmittance (and reflectance) of light changes gradually in accordance with the change in wavelength in a predetermined wavelength range (wavelength range of λ1 to λ2), and the transmittance (and reflectance) of light is constant regardless of the change in wavelength in wavelength ranges other than the predetermined wavelength range (i.e., on the lower wavelength side than the wavelength λ1 and the higher wavelength side than the wavelength λ2). In other words, in the predetermined wavelength range (wavelength range of λ1 to λ2), the transmittance of light changes monotonically increasing (reflectance changes monotonically) in accordance with the change in wavelength. The transmittance and reflectance are in a negative correlation in which when one changes in the direction of increasing, the other changes in the direction of decreasing, and therefore, in the following, the term "transmittance (and reflectance)" may not be used but may be simply used as "transmittance". In addition, "the light transmittance is constant regardless of the change in wavelength" includes not only the case where it is completely constant, but also the case where the change in the light transmittance for a change in wavelength of 1 nm is 0.1% or less. On the wavelength side lower than the wavelength λ1, the light transmittance is approximately 0% regardless of the change in wavelength, and on the wavelength side higher than the wavelength λ2, the light transmittance is approximately 100% regardless of the change in wavelength. In addition, "the light transmittance is approximately 0%" includes a transmittance of about 0%+10%, and "the light transmittance is approximately 100%" includes a transmittance of about 100%-10%. As described above, the LRG filter 61 is a separation optical element in which the wavelength band in which the transmittance changes according to the change in wavelength has a predetermined width (width of wavelengths λ1 to λ2).

[0039] Returning to FIG. 1, the camera 62 captures the light transmitted through the LRG filter 61 and outputs a transmitted image (first image data). The camera 62 also captures the light output from the light output unit 102 that reaches the camera without passing through the LRG filter 61 and outputs a total light amount image (second image data). In this way, the camera 62 may perform a first image capture of the light transmitted through the LRG filter 61, or may perform a second image capture of the light that reaches the camera without passing through the LRG filter 61. The first image capture and the second image capture are switched by changing the position of the LRG filter 61 by the switching unit 63 described later. Note that instead of the camera 62, an area image sensor such as a CCD or MOS may be used, or a line sensor or a TDI (Time Delay Integration) sensor may be used.

[0040] The switching unit 63 is configured to be able to switch between a state in which the LRG filter 61 is provided in the optical path between the light output unit 102 and the camera 62 (a state in which the first image is captured) and a state in which the LRG filter 61 is not provided (a state in which the second image is captured). The switching unit 63 realizes the switching by moving the LRG filter 61 (changing the position of the LRG filter 61). That is, when the first image is captured, the switching unit 63 moves the LRG filter 61 so that the LRG filter 61 is positioned in the optical path between the light output unit 102 and the camera 62 and light transmitted through the LRG filter 61 is captured by the camera 62. When the second image is captured, the switching unit 63 moves the LRG filter 61 so that the LRG filter 61 is not positioned in the optical path between the light output unit 102 and the camera 62 and light that reaches the camera 62 without passing through the LRG filter 61 is captured by the camera 62. The switching unit 63 may be, for example, a filter wheel or a filter slide.

[0041] The computer 70 is physically configured to include memories such as RAM and ROM, a processor (arithmetic circuit) such as a CPU, a communication interface, and a storage unit such as a hard disk. The computer 70 functions by the CPU executing a program stored in the memory. The computer 70 may be configured with a microcomputer or an FPGA.

[0042] The computer 70 executes a first process to derive wavelength information of the light output from the light output unit 102 of the PIC100 based on the above-mentioned transmitted image and total light image. In the first process, the computer 70 derives the transmitted intensity (amount of transmitted light), which is the intensity of the light transmitted through the LRG filter 61, based on the transmitted image, and derives the total intensity of the light output from the light output unit 102 based on the total light image. Then, the computer 70 derives the reflected intensity (amount of reflected light), which is the intensity of the light reflected by the LRG filter 61, based on the transmitted intensity and the total intensity, specifically by subtracting the transmitted intensity from the total intensity. For example, if the transmitted intensity is T, the reflected intensity is R, the total light amount is A, and the difference between the transmitted intensity T and the reflected intensity R is D, then R=AT and D=2T-A are satisfied. The computer 70 derives wavelength information based on the transmitted light amount and the reflected light amount. The computer 70 derives the difference between the transmitted light amount and the reflected light amount, and derives wavelength information based on the difference value. The wavelength information here is information indicating the centroid wavelength of the light output from the light output unit 102. The transmission intensity (amount of transmitted light) may be an integrated value of the intensity of the image region corresponding to the light output unit 102 in the transmission image. The total intensity (total amount of light) may be an integrated value of the intensity of the image region corresponding to the light output unit 102 in the total amount of light image. In this case, the reflection intensity (amount of reflected light) derived by calculation is obtained as an integrated value of the intensity of the image region corresponding to the light output unit 102. The transmission intensity (amount of transmitted light) may be the intensity of each pixel constituting the image region corresponding to the light output unit 102 in the transmission image. The total intensity (total amount of light) may be the intensity of each pixel constituting the image region corresponding to the light output unit 102 in the total amount of light image. In this case, the reflection intensity (amount of reflected light) derived by calculation is obtained as the intensity of each pixel constituting the image region corresponding to the light output unit 102. Hereinafter, an example of the calculation principle of the centroid wavelength will be described in detail with reference to FIG. 4.

[0043] As described above, the LRG filter 61 reflects all light at wavelengths shorter than λ1 and transmits all light at wavelengths longer than λ2, and the transmittance of light changes linearly with wavelength in the wavelength band from λ1 to λ2. In this case, the transmittance h(λ) in relation to the wavelengths λ1 and λ2 is expressed by the following formula (1), and the reflectance 1-h(λ) is expressed by the following formula (2). h(λ)=(λ-λ1) / (λ2-λ1) (1) 1-h(λ)=(λ2-λ) / (λ2-λ1) (2)

[0044] It is also clear that the wavelength λ50% at which the reflectance becomes 50% is expressed by the following formula (3). λ50%=(λ2+λ1) / 2 (3)

[0045] When a spectrum f(λ) is shown by waveform X2 in FIG. 4, is between λ1 and λ2, and can be ignored at wavelengths shorter than λ1 and longer than λ2, the following equation (4) holds if we assume that the amount of reflected light is equal to the amount of transmitted light. ∫f(λ)h(λ)dλ=∫f(λ)(1-h(λ))dλ (4) Transforming equation (4) gives us equation (5) below. 2∫f(λ)h(λ)dλ=∫f(λ)dλ (5)

[0046] Substituting equation (1) into equation (5), we get 2∫f(λ)(λ-λ1) / (λ2-λ1)dλ=∫f(λ)dλ Further dividing both sides by 2∫f(λ)dλ / (λ2-λ1), we get ∫f(λ)(λ-λ1)dλ / ∫f(λ)dλ= (λ2-λ1) / 2 ∫f(λ)λdλ / ∫f(λ)dλ= (λ2+λ1) / 2 (6) It becomes.

[0047] Considering equation (3), it is clear that the right side of equation (6) is λ50% and the left side is the center of gravity of f(λ), which is generally an arbitrary function. The left side of equation (6) is assumed to be λf. From the above, for any spectrum that has passed through an LRG filter 61 whose transmittance changes linearly with wavelength, when the amount of transmitted light and the amount of reflected light are equal, the center of gravity λf of the spectrum is indicated as λ50%.

[0048] Next, consider the second spectrum g(λ). The spectrum g(λ) is also entirely contained between λ1 and λ2. Now, calculate the difference between the normalized differential values ​​of the transmitted light and reflected light for spectra f(λ) and g(λ). The transmitted light of f(λ) is Tf, the reflected light is Rf, the total amount of light is Af, and the differential value between the transmitted light and reflected light is Df. The transmitted light of g(λ) is Tg, the reflected light is Rg, the total amount of light is Ag, and the differential value between the transmitted light and reflected light is Dg. The center of gravity of g(λ) is λg. In this case, Tf, Rf, Tg, and Rg are measured values, and Af, Ag, Df, and Dg are values ​​that can be calculated directly from the measured values. Each of these values ​​can also be expressed by the following formulas. Tf=∫f(λ)h(λ)dλ=∫f(λ)(λ-λ1) / (λ2-λ1)dλ (7) Tg=∫g(λ)h(λ)dλ=∫g(λ)(λ-λ1) / (λ2-λ1)dλ (8) Rf=∫f(λ)(1-h(λ))dλ=∫f(λ)(λ2-λ) / (λ2-λ1)dλ (9) Rg=∫g(λ)(1-h(λ))dλ=∫g(λ)(λ2-λ) / (λ2-λ1)dλ (10) Af = ∫f(λ)dλ (11) Ag = ∫g(λ)dλ (12) Df=Tf-Rf =2 / (λ2-λ1)*∫λf(λ)dλ-(λ2+λ1) / (λ2-λ1)*∫f(λ)dλ (13) Dg = Tg - Rg =2 / (λ2-λ1)*∫λg(λ)dλ-(λ2+λ1) / (λ2-λ1)*∫g(λ)dλ (14)

[0049] Here, normalizing the difference between the transmitted light and the reflected light corresponds to dividing Df by Af and Dg by Ag. If the difference between them is R, then the following equation (15) is established. R=Dg / Ag-Df / Af ={∫g(λ)λdλ / ∫g(λ)dλ-∫f(λ)λdλ / ∫f(λ)dλ}*2 / (λ2-λ1) =2(λg-λf) / (λ2-λ1) (15)

[0050] If the difference between the centroid wavelength λf of spectrum f(λ) and the centroid wavelength λg of spectrum g(λ) is δλ, the following equations (16) and (17) hold. R = 2δλ / (λ2-λ1) (16) δλ=R(λ2-λ1) / 2 (17) As described above, it has been shown that the difference in the center of gravity of two arbitrary spectra f(λ) and g(λ) can be obtained from a calculation that takes into account the amount of transmitted light and the amount of reflected light.

[0051] When the center of gravity of f(λ) is λ50%, the amount of reflected light and the amount of transmitted light are equal, so Df is 0. In other words, the center of gravity wavelength λg of any spectrum g(λ) is expressed by the following equation (18). λg=δλ+λ50% (18)

[0052] As described above, the centroid wavelength of the spectrum (i.e., wavelength information of light) can be calculated from the design value, transmitted light amount, and reflected light amount of the LRG filter 61. Then, in the inspection device 1, as described above, the centroid wavelength (wavelength information) is used to inspect the PIC100.

[0053] The centroid wavelength λg of an arbitrary spectrum g(λ) can also be found by the following formulas (19) and (20). In this case, the transmitted light Tg, reflected light Rg, total light amount Ag, and centroid λg of g(λ) are defined by formulas (21), (22), (23), and (24), respectively. Note that formula (21) is synonymous with formula (8) above, formula (22) is synonymous with formula (10) above, formula (23) is synonymous with formula (12) above, and formula (24) is synonymous with formula (18) above.

number

[0054] Next, steps of an inspection method performed using the inspection device 1 will be described with reference to Figs. 5 to 20. This inspection method broadly includes a preparation step and a step of deriving wavelength information. The preparation step includes a setting step, a step of roughly specifying the position of the light input unit 101, a step of roughly specifying the position of the light output unit 102, a step of highly accurately specifying the position of the light input unit 101, and a step of highly accurately specifying the position of the light output unit 102.

[0055] The inspection device 1 that performs each of the above-mentioned steps has a configuration shown in detail in Fig. 5. Fig. 5 is a side view showing the details of the inspection device 1 shown in Fig. 1. As shown in Fig. 5, the inspection device 1 is configured to include a first scanner unit 200 (first optical scanner unit), a second scanner unit 300 (second optical scanner unit), a condenser lens 401, and an observation camera 402 in addition to the configuration shown in Fig. 1. The condenser lens 401 and the observation camera 402 are components used in the advance preparation process.

[0056] The first scanner unit 200 is configured to perform optical scanning on an input end face 100a (first region) of the PIC 100 on which a plurality of optical input sections 101 are formed, and detect light related to the optical scanning (specifically, light reflected at the input end face 100a).

[0057] The first scanner unit 200 includes a laser light source 201, a photodiode 202, a galvanometer mirror 203, a mirror 240, and a condenser lens 250. The laser light source 201 is a light source that emits laser light. The galvanometer mirror (optical scanner) 203 is an optical scanner that reflects the light emitted from the laser light source 201 in an arbitrary direction and realizes optical scanning on the input end face 100a. The condenser lens 250 is, for example, an objective lens, and condenses the light on the mirror 240. The mirror 240 reflects the light from the condenser lens 250 toward the input end face 100a of the PIC 100. The photodiode 202 is a photodetector that detects the light reflected at the input end face 100a. The photodiode 202 outputs a signal related to the detected light to the computer 70.

[0058] The second scanner unit 300 is configured to perform optical scanning on an output end surface 100b (second region) of the PIC 100 on which a plurality of optical output units 102 are formed, and detect light related to the optical scanning (specifically, light reflected at the output end surface 100b).

[0059] The second scanner unit 300 includes a laser light source 301, a photodiode 302, and a galvanometer mirror (optical scanner) 303. The laser light source 301 is a light source that emits laser light. The galvanometer mirror 303 is an optical scanner that reflects the light emitted from the laser light source 201 in an arbitrary direction and realizes optical scanning on the output end face 100b. The light from the galvanometer mirror 303 passes through the condenser lens 50 and the mirror 40 and is irradiated onto the output end face 100b of the PIC 100. The photodiode 302 is a photodetector that detects the light reflected at the output end face 100b. The photodiode 302 outputs a signal related to the detected light to the computer 70.

[0060] Observation camera 402 is a camera for observing how the probe card 30 applies a needle to the chip of PIC 100. Observation camera 402 performs the above observation by detecting light that has passed through condenser lens 401, which is an objective lens, for example.

[0061] The following chronologically describes the preparation steps (a setting step, a step of roughly determining the position of the optical input section 101, a step of roughly determining the position of the optical output section 102, a step of determining the position of the optical input section 101 with high accuracy, and a step of determining the position of the optical output section 102 with high accuracy) and the step of deriving wavelength information.

[0062] (Setting process) 6(a) to (c) and 7 are diagrams for explaining the setting process. First, as shown in FIG. 6(a), the chip of PIC100 is attached to a recess on the upper surface of the stage 10. Then, as shown in FIG. 6(b), the PIC100 is fixed to the stage 10, and the position and direction (tilt) of the stage 10 are adjusted. Next, as shown in FIG. 7 and FIG. 6(c), the needles of the probe card 30 are brought into contact with the chip of PIC100 while the position of the probe card 30 is observed by an observation camera 402. This completes the setting process.

[0063] (Step of roughly identifying the position of the light input unit 101) 8 to 10 are diagrams for explaining a process of roughly identifying the position of the light input section 101. As shown in FIG. 8, the first scanner section 200 irradiates light onto the input end face 100a of the PIC 100. As shown in FIG. 9, the first scanner section 200 scans the irradiation area of ​​the light SC1 from the laser light source 201 on the input end face 100a in the horizontal and / or vertical directions to perform light scanning. Here, as shown in FIG. 10, the input end face 100a has a plurality of light input sections 101 (input sections 101a, 101b, 101c, 101d, 101e, and 101f in the example of FIG. 10), and the diameter of the light SC1 scanned on the input end face 100a is larger than the diameter of the light input sections 101a to 101f. The diameter of the light input sections 101a to 101f is, for example, 1 μm or less, and may be about 0.5 μm. The photodiode 202 of the first scanner unit 200 detects the light reflected at the input end face 100a and outputs a signal related to the detected signal to the computer 70. The signal is a signal indicating at least the intensity of the light detected by the photodiode 202. Note that, before optical scanning, the position of the stage 10 or the first scanner unit 200 may be adjusted so that the input end face 100a of the PIC 100 is in focus.

[0064] Then, the computer 70 specifies the rough positions of the light input units 101a-101f based on the signal (signal indicating the intensity of the detected light) output by the photodiode 202 of the first scanner unit 200. Such processing is a second processing for specifying in advance the positions of the light input units 101a-101f to which light is input when performing the first processing for deriving the wavelength information of light. The computer 70 specifies the positions of the light input units 101a-101f from the difference in light intensity according to the difference between the reflectance at the light input units 101a-101f and the reflectance at the regions of the input end face 100a other than the light input units 101a-101f. The positions of the light input units 101a-101f specified here are rough positions, and are specified in detail in the "step of specifying the position of the light input unit 101 with high accuracy" described later.

[0065] (Step of roughly identifying the position of the light output unit 102) 11 to 13 are diagrams for explaining the process of roughly identifying the position of the optical output unit 102. As shown in FIG. 11, the second scanner unit 300 irradiates the output end surface 100b of the PIC 100 with light. As shown in FIG. 12, the second scanner unit 300 scans the irradiation area of ​​the light SC2 from the laser light source 301 on the output end surface 100b in the horizontal and / or vertical directions to perform optical scanning. Here, as shown in FIG. 13, the output end surface 100b has a plurality of output units 102 (in the example of FIG. 13, the output units 102a, 102b, 102c, 102d, 102e, and 102f), and the diameter of the light SC2 scanned on the output end surface 100b is larger than the diameter of the optical output units 102a to 102f. The diameter of the optical output units 102a to 102f is, for example, 1 μm or less, and may be about 0.5 μm. The photodiode 302 of the second scanner unit 300 detects the light reflected at the output end face 100b and outputs a signal related to the detected signal to the computer 70. The signal is a signal indicating at least the intensity of the light detected by the photodiode 302. Note that, before optical scanning, the position of the stage 10 or the second scanner unit 300 may be adjusted so that the output end face 100b of the PIC 100 is in focus.

[0066] Then, the computer 70 specifies the rough positions of the light output units 102a-102f based on the signal (signal indicating the intensity of the detected light) output by the photodiode 302 of the second scanner unit 300. This process is a third process for specifying in advance the positions of the light output units 102a-102f that output light when performing the first process for deriving wavelength information of light. The computer 70 specifies the positions of the light output units 102a-102f from the difference in light intensity corresponding to the difference between the reflectance of the light output units 102a-102f and the reflectance of the region of the output end face 100b other than the light output units 102a-102f. The positions of the light output units 102a-102f specified here are rough positions, and are specified in detail in the "step of specifying the position of the light output unit 102 with high accuracy" described later.

[0067] (Step of identifying the position of the light input unit 101 with high accuracy) 14 and 15 are diagrams for explaining the process of identifying the position of the light input unit 101 with high accuracy. As shown in FIG. 14 and FIG. 15, in a state where the second scanner unit 300 is positioned at a predetermined light output unit 102 (the light output unit 102 whose position has been identified by the process of roughly identifying the position of the light output unit 102), the first scanner unit 200 inputs light to each light input unit 101 (light input units 101a to 101f). Then, the light output from the light output unit 102 is detected by the photodiode 302 of the second scanner unit 300. The first scanner unit 200 scans the light input units 101a to 101f (and their surroundings) whose positions have already been roughly identified with light, and the light intensities are detected by the photodiodes 302, so that the positions of the light input units 101a to 101f can be identified with high accuracy based on the difference in light intensity.

[0068] (Step of identifying the position of the light output unit 102 with high accuracy) 14 and 16 are diagrams for explaining the process of identifying the position of the light output unit 102 with high accuracy. As shown in Fig. 14 and 16, in a state where the first scanner unit 200 is positioned at a predetermined light input unit 101, the first scanner unit 200 inputs light to the light input unit 101. Then, the light output from the PIC 100 is detected by the photodiode 302 of the second scanner unit 300. The second scanner unit 300 scans the light output units 102a-102f (and their surroundings) whose positions have already been roughly identified with light, and the light intensities are detected by the photodiodes 302, respectively, so that the positions of the light output units 102a-102f can be identified with high accuracy from the difference in light intensity.

[0069] (Step of deriving wavelength information) 17 to 19 are diagrams for explaining the process of deriving wavelength information. As shown in FIG. 17, first, the imaging mechanism 60 is positioned so that the light output from the plurality of light output units 102a to 102f can be imaged collectively. Specifically, the switching unit 63 moves the LRG filter 61 so that the LRG filter 61 is positioned in the optical path between the light output units 102a to 102f and the camera 62, and the light transmitted through the LRG filter 61 is imaged by the camera 62. In this case, the LRG filter 61 transmits or reflects the light (see FIG. 18) input from the light input unit 101, guided by the waveguide 108, and output from the light output unit 102 based on the transmission characteristics. Then, in a state where light is input to the desired light input unit 101, the light output from the light output unit 102 of the PIC100 and transmitted through the LRG filter 61 is imaged by the camera 62.

[0070] Next, the switching unit 63 moves the LRG filter 61 so that the LRG filter 61 is not positioned in the optical path between the optical output units 102a to 102f and the camera 62, and light that arrives without passing through the LRG filter 61 is imaged by the camera 62. In this case, with light being input to the desired optical input unit 101, the light that is output from the optical output unit 102 of the PIC100 and arrives without passing through the LRG filter 61 is imaged by the camera 62.

[0071] Fig. 19(a) is an image of the light output unit 102 captured by the camera 62, showing an image 802 (transmitted image) of light transmitted through the LRG filter 61, and Fig. 19(b) is an image of the light output unit 102 captured by the camera 62, showing an image 902 (total light image) of light that has reached the light output unit 102 without passing through the LRG filter 61. These images 802, 902 each show an image corresponding to the amount of captured light. In other words, the integrated value of the intensities of the multiple pixels constituting the image 802 may be the transmitted intensity (transmitted light amount), or the integrated value of the intensities of the multiple pixels constituting the image 902 may be the total intensity (total light amount).

[0072] The computer 70 executes a first process to derive wavelength information (specifically, centroid wavelength) of the light output from each of the output units 102a to 102f based on the transmitted image and the total light amount image captured by the camera 62. An example of the method of deriving the centroid wavelength is as described above.

[0073] The computer 70 may create a table showing the relationship between the wavelength information derived in the first process and the information related to the temperature control of the PIC by the PIC controller 20 when the wavelength information was derived (for example, the power input to the microheater), thereby creating a table showing the relationship between the wavelength information and the temperature control of the PIC. Such a table can be used during normal PIC control (wavelength control of the PIC100). As described above, the PIC controller 20 supplies power to the microheater and controls the temperature of at least a part of the PIC100. By such temperature control, the refractive index of the light guided in the waveguide 108 of the PIC100 is controlled, and the wavelength of the light output from the PIC100 is controlled. For example, by varying the conditions of the power input to the microheater by the PIC controller 20 and deriving the wavelength information by the first process, a table in which the power input to the microheater and the wavelength information are associated, as shown in FIG. 20, can be created. In FIG. 20, the horizontal axis indicates the power input to the microheater, and the vertical axis indicates the amount of resonant wavelength shift (δλ in the above-mentioned formula (18)).

[0074] Next, a step of deriving wavelength information in the inspection method executed using the inspection device 1 will be described with reference to the flowchart shown in Fig. 21. Fig. 21 is a flowchart of the inspection method (specifically, the step of deriving wavelength information).

[0075] 21, in the process of deriving wavelength information, first, the operation of the PIC100 is controlled by the PIC controller 20 (step S1). Here, the control of the operation means the control of the operation of each element in the PIC100.

[0076] Next, the LRG filter 61 arranged in the optical path between the optical output unit 102 and the camera 62 transmits the light output from the optical output unit 102 (step S2).

[0077] Next, the light transmitted through the LRG filter 61 is captured by the camera 62, and the transmitted image is output to the computer 70 (step S3).

[0078] Next, the LRG filter 61 is retracted from the optical path between the light output unit 102 and the camera 62, and the light that reaches the camera 62 without passing through the LRG filter 61 is captured by the camera 62, and a total light image is output to the computer 70 (step S4).

[0079] Then, the computer 70 derives wavelength information of the light output from the light output section 102 based on the transmitted image and the total light amount image (step S5).

[0080] Next, the effects of the inspection device 1 according to this embodiment will be described.

[0081] The inspection device 1 is an inspection device for inspecting a PIC100 having at least one optical output unit 102 and a waveguide 108, and includes a stage 10 for holding the PIC100, a PIC controller 20 for controlling the operation of the PIC100, an LRG filter 61 having transmission characteristics in which the transmittance changes linearly in a predetermined wavelength range, and transmitting or reflecting light guided by the waveguide 108 and output from at least one optical output unit 102 based on the transmission characteristics, a camera 62 for capturing an image of the light that has transmitted through the LRG filter 61 and outputting a transmitted image, and for capturing an image of the light output from the optical output unit 102 that has reached the optical output unit 102 without passing through the LRG filter 61 and outputting a total light image, and a computer 70 for executing a first process to derive wavelength information of the light output from the optical output unit 102 based on the transmitted image and the total light image.

[0082] In the inspection device 1 according to the present embodiment, the light output from the light output unit 102 of the PIC100 is transmitted or reflected by the LRG filter 61 according to the wavelength. Then, based on the transmission image capturing the light transmitted or reflected by the LRG filter 61 and the total light amount image capturing the light that reaches without passing through the LRG filter 61, the wavelength information of the light output from the light output unit 102 is derived. In this way, in the inspection device 1 according to the present embodiment, the LRG filter 61 is used to transmit or reflect the light according to the wavelength, so the transmission image becomes image data according to the wavelength of the light. Also, since the transmission image is image data capturing the light transmitted through the LRG filter 61 and the total light amount image is image data capturing the light that reaches without passing through the LRG filter 61, it is possible to obtain information on not only the light transmitted through the LRG filter 61 but also the light reflected by the LRG filter 61 from these image data. In this way, by obtaining information on the light transmitted or reflected according to the wavelength, it is possible to obtain the wavelength information of the light with high accuracy. As described above, the inspection device 1 of this embodiment can acquire information (specifically, wavelength information) of the light output from the PIC100, and as a result, the wavelength information can be used to properly inspect the PIC100.

[0083] The PIC100 has a plurality of optical output units 102a-102f, and the LRG filter 61 may transmit or reflect each of the lights output from the plurality of optical output units 102a-102f based on the transmission characteristics. With such a configuration, wavelength information of the lights from the plurality of optical output units 102a-102f provided at spatially different positions is acquired all at once, and the PIC100 can be inspected more quickly and appropriately.

[0084] The imaging unit may have a camera 62 which is an image sensor that captures light transmitted through or reflected by the LRG filter 61, and captures light output from the light output unit 102 that reaches the imager without passing through the LRG filter 61. Such a camera 62 can appropriately capture the desired light.

[0085] The inspection device 1 may further include a switching unit 63 configured to be able to switch between a state in which the LRG filter 61 is provided and a state in which the LRG filter 61 is not provided in the optical path between the light output unit 102 and the camera 62. With this configuration, it is possible to appropriately acquire both the transmitted image and the total light image described above while switching between the presence and absence of the LRG filter 61.

[0086] The PIC controller 20 may control the temperature of at least a part of the PIC 100. By controlling the temperature of the PIC 100 in this manner, the refractive index of the waveguide constituting the optical ring resonator circuit 110 of the PIC 100 can be changed, and for example, the resonant wavelength of light in the optical ring resonator circuit 110 can be controlled. This makes it possible to appropriately inspect the PIC 100 while easily changing the conditions of the wavelength of light.

[0087] The PIC100 has at least one optical input unit 101, and the optical output unit 102 may output light that is input from the optical input unit 101 and guided by the waveguide 108. With this configuration, it is possible to appropriately obtain wavelength information about the light that is input from the optical input unit 101 of the PIC100, passes through the waveguide 108, and is output from the optical output unit 102.

[0088] The inspection device 1 further includes a first scanner unit 200 that performs an optical scan on the input end surface 100a of the PIC 100 on which the optical input unit 101 is formed and detects the light associated with the optical scan, and the computer 70 may further execute a second process for identifying in advance the position of the optical input unit 101 to which the light is input when the first process is performed, and in the second process, the position of the optical input unit 101 may be identified based on the intensity of the light detected by the first scanner unit 200. With this configuration, the position of the optical input unit 101 can be identified based on the difference in the intensity of the light, and the subsequent first process (process for deriving wavelength information of the light output from the optical output unit 102) can be appropriately performed.

[0089] The inspection device 1 further includes a second scanner unit 300 that performs an optical scan on the output end surface 100b of the PIC 100 on which the optical output unit 102 is formed and detects the light related to the optical scan, and the computer 70 may further execute a third process for identifying in advance the position of the optical output unit 102 that outputs light when the first process is performed, and in the third process, the position of the optical output unit 102 may be identified based on the intensity of the light detected by the second scanner unit 300. With this configuration, the position of the optical output unit 102 can be identified from the difference in the intensity of the light, and the subsequent first process (process for deriving wavelength information of the light output from the optical output unit 102) can be appropriately performed.

[0090] In the first process, the computer 70 may derive a transmission intensity, which is the intensity of light transmitted through the LRG filter 61, from the transmission image, and may also derive a total intensity of light output from the light output unit 102 from the total light amount image, derive a reflection intensity, which is the intensity of light reflected by the LRG filter 61, based on the transmission intensity and the total intensity, and derive wavelength information based on the transmission intensity and reflection intensity. Since light is transmitted or reflected in the LRG filter 61 according to the wavelength, it is possible to derive wavelength information with high accuracy from information on the transmission intensity (amount of transmitted light) and reflection intensity (amount of reflected light).

[0091] The computer 70 may derive a difference value between the transmission intensity and the reflection intensity, and derive the wavelength information based on the difference value. By deriving the wavelength information from the difference value between the transmission intensity and the reflection intensity, the wavelength information can be derived with high accuracy.

[0092] The wavelength information may be information indicating the centroid wavelength of the light output from the light output unit 102. This makes it possible to appropriately derive the wavelength information.

[0093] The computer 70 may further execute a fourth process of creating a table showing the relationship between the wavelength information and the temperature control of the PIC 100 by the PIC controller 20 when the wavelength information was derived, by associating the wavelength information derived in the first process with information related to the temperature control of the PIC 100 by the PIC controller 20. With this configuration, a table of temperature control when adjusting the wavelength of the PIC 100 can be created, making it easier to control the PIC 100.

[0094] [Second embodiment] Next, a second embodiment of the present disclosure will be described with reference to Fig. 22 to Fig. 25. In the second embodiment, differences from the first embodiment will be mainly described, and descriptions overlapping with the first embodiment will be omitted.

[0095] Fig. 22 is a side view showing a schematic diagram of an inspection device 1A according to the second embodiment. The inspection device 1A has a similar configuration to the inspection device 1. The inspection device 1A derives wavelength information about light output from a grating 103 (see Fig. 25), which is an optical output section provided on the front surface (top surface) of the PIC100. In this case, the imaging mechanism 60 is disposed so as to be located directly above the front surface (top surface) of the PIC100 so as to be able to image the light output from the grating 103.

[0096] The steps of the inspection method performed using the inspection device 1A will be described. In this inspection method, as in the inspection method according to the first embodiment, a setting step (see FIGS. 6(a) to 6(c)) is performed first. Then, as necessary, a step of roughly specifying the position of the light input unit 101 and a step of specifying the position of the light input unit 101 with high accuracy are performed. These steps are the same as those described in the first embodiment. Then, a step of specifying the position of the grating 103 is performed. Specifically, as shown in FIGS. 23 and 24, the first scanner unit 200 inputs light to the light input unit 101 of the PIC100, and the camera 62 captures the light from the grating 103 formed on the front surface (top surface) of the PIC100. In this case, light is input to each light input unit 101 by scanning with the first scanner unit 200. In this way, the light from the grating 103 is captured by the camera 62, so that the position of the grating 103 formed on the front surface (top surface) of the PIC 100 can be identified with high accuracy.

[0097] Next, a step of deriving wavelength information is performed. Specifically, first, the imaging mechanism 60 is positioned so as to image the light output from the grating 103. Specifically, the LRG filter 61 transmits or reflects the light output from the grating 103 based on the transmission characteristics. At this time, the focusing lens 50 and / or the stage 10 may be adjusted in the optical axis direction of the focusing lens 50 so as to focus on the front surface (top surface) of the PIC100. Then, with light input to the desired light input unit 101, light is output from the grating 103 formed on the front surface (top surface) of the PIC100 (see FIG. 25), the light is transmitted or reflected by the LRG filter 61, and the transmitted light is imaged by the camera 62.

[0098] Furthermore, after the LRG filter 61 is retracted from the optical path, with light being input to the desired optical input section 101, light is output from the grating 103 formed on the front surface (top surface) of the PIC 100 (see Figure 25), and the light is imaged by the camera 62.

[0099] Then, based on the transmitted image and the total light amount image captured by the camera 62, the computer 70 derives wavelength information (specifically, the centroid wavelength) of the light output from the grating 103.

[0100] [Third embodiment] Next, a third embodiment of the present disclosure will be described with reference to Fig. 26 and Fig. 27. In the third embodiment, differences from the first and second embodiments will be mainly described, and descriptions overlapping with the first and second embodiments will be omitted.

[0101] 26 and 27 are diagrams for explaining the process of deriving wavelength information in the third embodiment. As shown in Fig. 26, in the third embodiment, light is emitted from a laser element 104 inside the PIC100, and the light is output from a plurality of gratings 103 formed on the front surface (upper surface) of the PIC100. That is, in the third embodiment, light generated by a laser element 104 inside the PIC100 is output from a plurality of gratings 103, instead of light input from the outside of the PIC100 to the inside of the PIC100.

[0102] The steps of the inspection method in this case will be described below. In this inspection method, similarly to the inspection method according to the second embodiment, advance preparation steps such as a setting step are carried out, followed by a step of deriving wavelength information.

[0103] In the process of deriving wavelength information, first, the imaging mechanism 60 is positioned so that the light output from the multiple gratings 103 can be imaged collectively. Specifically, the LRG filter 61 transmits or reflects the light output from the multiple gratings 103 based on the transmission characteristics. At this time, the focusing lens 50 and / or the stage 10 may be adjusted in the optical axis direction of the focusing lens 50 so that the focus is adjusted to the front surface (top surface) of the PIC100. Then, in a state where light is emitted from the laser element 104 inside the PIC100, light is output from the multiple gratings 103 formed on the front surface (top surface) of the PIC100 (see FIG. 26), the light is transmitted or reflected by the LRG filter 61, and the transmitted light is imaged by the camera 62.

[0104] In addition, after the LRG filter 61 is retracted from the optical path, while light is emitted from the laser element 104 inside the PIC100, light is output from multiple gratings 103 formed on the front surface (top surface) of the PIC100 (see Figure 26), and the light is imaged by the camera 62.

[0105] Fig. 27(a) is an image of a plurality of gratings 103 captured by camera 62, showing an image 812 (transmitted image) of light transmitted through LRG filter 61, and Fig. 27(b) is an image of a plurality of gratings 103 captured by camera 62, showing an image 912 (reflected image) of light that has arrived without passing through LRG filter 61. These images 812, 912 each show an image corresponding to the amount of light captured.

[0106] Then, based on the transmitted image and the total light amount image captured by the camera 62, the computer 70 derives wavelength information (specifically, the centroid wavelength) of the light output from each grating 103.

[0107] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above.

[0108] 28(a) and (b) are diagrams illustrating an imaging mechanism 160 according to a first modified example. The imaging mechanism 160 differs from the imaging mechanism 60 in that a switching unit 163 is configured to be able to switch between the LRG filter 61 and the normalization filter 161.

[0109] The imaging mechanism 160 has an LRG filter 61, a normalization filter 161, a camera 62, and a switching unit 163. The normalization filter 161 is a filter that reduces the amount of light spatially uniformly, for example, an ND filter. The switching unit 163 is configured to be able to switch between a state in which the LRG filter 61 is provided in the optical path between the light output unit 102 and the camera 62 (see FIG. 28(a)) and a state in which the LRG filter 61 is not provided and the normalization filter 161 is provided (see FIG. 28(b)). The switching unit 163 may realize the above switching by moving the LRG filter 61 and the normalization filter 161.

[0110] When a normalization filter 161 is provided in the optical path, for example, a normalization filter 161 that outputs light at approximately 50% of the amount of incident light is used, and the brightness of the camera 62 is approximately doubled, so that the total amount of light in a state in which the LRG filter 61 is not provided (the total amount of light output from the optical output unit 102) may be derived.

[0111] 29(a) and (b) are diagrams illustrating an imaging mechanism 260 according to a second modified example. The imaging mechanism 260 differs from the imaging mechanism 60 in that the camera 62 captures an image of light reflected by the LRG filter 61.

[0112] The imaging mechanism 260 has an LRG filter 61, a mirror 261, a camera 62, and a switching unit 263. The switching unit 263 is configured to be able to switch between a state in which the LRG filter 61 is provided in the optical path between the light output unit 102 and the camera 62 (see FIG. 29(a)), and a state in which the LRG filter 61 is not provided and the mirror 261 is provided (see FIG. 29(b)). The switching unit 163 may realize the above switching by moving the LRG filter 61 and the mirror 261.

[0113] In this case, camera 62 is provided at a position to capture an image of light reflected by LRG filter 61 when LRG filter 61 is provided in the optical path (see FIG. 29(a)), and is provided at a position to capture an image of light reflected by mirror 261 when mirror 261 is provided in the optical path (see FIG. 29(b)). When mirror 261 is provided in the optical path, the total amount of light output from light output unit 102 is acquired.

[0114] In the first process, the computer 70 derives a reflection intensity, which is the intensity of light reflected by the LRG filter 61, from the reflection image (see FIG. 29(a)), and also derives the total intensity of light output from the light output unit 102 from the total light amount image (see FIG. 29(b)). Based on the reflection intensity and the total intensity, the computer 70 derives a transmitted intensity, which is the intensity of light transmitted through the LRG filter 61, and based on the transmitted intensity and reflection intensity, derives wavelength information.

[0115] In detail, the computer 70 executes a first process to derive wavelength information of the light output from the light output unit 102 of the PIC100 based on the above-mentioned reflected image and total light image. In the first process, the computer 70 derives the reflection intensity (reflected light amount), which is the intensity of the light reflected from the LRG filter 61, based on the reflected image, and also derives the total intensity (total light amount) of the light output from the light output unit 102 based on the total light image. Then, the computer 70 derives the transmission intensity (transmitted light amount), which is the intensity of the light transmitted through the LRG filter 61, based on the reflected intensity and the total intensity, specifically by subtracting the reflected intensity from the total intensity. For example, when the transmitted intensity is T, the reflected intensity is R, the total light amount is A, and the difference between the transmitted intensity T and the reflected intensity R is D, T=AR and D=A-2R are established. In addition, the reflection intensity (reflected light amount) may be an integrated value of the intensity of the image area corresponding to the light output unit 102 in the reflected image. Furthermore, the total intensity (total amount of light) may be an integrated value of the intensities of the image region corresponding to the light output unit 102 in the total light amount image. In this case, the transmitted intensity (amount of transmitted light) derived by calculation is found as an integrated value of the intensities of the image region corresponding to the light output unit 102. Furthermore, the reflected intensity (amount of reflected light) may be the intensity of each pixel constituting the image region corresponding to the light output unit 102 in the reflected image. Furthermore, the total intensity (total amount of light) may be the intensity of each pixel constituting the image region corresponding to the light output unit 102 in the total light amount image. In this case, the transmitted intensity (amount of transmitted light) derived by calculation is found as the intensity of each pixel constituting the image region corresponding to the light output unit 102.

[0116] 30(a) is a diagram illustrating an imaging mechanism 360 according to a third modified example. The imaging mechanism 360 differs from the imaging mechanism 60 in that it has two cameras 62, 363 and simultaneously captures a transmitted image and a total light image.

[0117] The imaging mechanism 360 has an LRG filter 61, a camera 62 (first image sensor), a camera 363 (second image sensor), and a beam splitter 364 (light branching section). The beam splitter 364 is a splitter that branches the light output from the light output section 102 into a transmission light path 399x (first branched light path) and a reflection light path 399y (second branched light path). The beam splitter 364 is, for example, a half mirror, and branches (splits) the light by transmitting and reflecting it. The camera 62 is disposed on the transmission light path 399x. The camera 363 is disposed on the reflection light path 399y. The LRG filter 61 is disposed on the transmission light path 399x.

[0118] According to this configuration, the light output from the light output unit 102 is split by the beam splitter 364 into a transmitted light path 399x and a reflected light path 399y, and the camera 62 provided on the transmitted light path 399x can obtain a transmitted image (first image data) and the camera 363 provided on the reflected light path 399y can obtain a total light amount image (second image data) simultaneously. This makes it possible to efficiently derive wavelength information.

[0119] 30(b), the LRG filter 61 may be disposed on the reflected light path 399y. In this case, the reflected light path 399y is the first branched light path, and the transmitted light path 399x is the second branched light path.

[0120] 31, the imaging mechanism 60 may have a sensitivity correction filter 550 that flattens the spectral sensitivity characteristics of the entire optical system in front of the LRG filter (optical filter) 61. By providing the sensitivity correction filter 550, the center of gravity of the wavelengths of light having a wavelength range can be obtained more accurately. The sensitivity correction filter 550 may be provided between the LRG filter (optical filter) 61 and the camera (image sensor) 62.

[0121] Furthermore, although the description has been given assuming that the computer 70 separate from the camera 62 derives the wavelength information, this is not limiting, and each process such as deriving the wavelength information may be performed by an integrated circuit in the camera. Also, a heater or cooler for adjusting the temperature of the PIC may be provided inside the PIC or outside the PIC. Also, a PIC controller for controlling the operation of the PIC may be connected from outside the PIC by a tester or the like, or may be connected via a board electrically connected to the board of the PIC. [Explanation of symbols]

[0122] 1, 1A... inspection device, 10... stage, 20... PIC controller, 61... LRG filter (optical filter), 62... camera (imaging section, image sensor, first image sensor), 70... computer (analysis section), 100a... input end face (first region), 100b... output end face (second region), 101... optical input section, 102... optical output section, 103... grating (optical output section), 108... waveguide, 200... first scanner section (first optical scanner section), 300... second scanner section (second optical scanner section). 363... camera (second image sensor).

Claims

1. 1. An inspection apparatus for inspecting a photonic integrated circuit having at least one optical output and a waveguide, comprising: a stage for holding the photonic integrated circuit; A control unit that controls an operation of the photonic integrated circuit; an optical filter having a transmission characteristic in which the transmittance changes linearly in a predetermined wavelength range, and transmitting or reflecting the light guided by the waveguide and output from the at least one optical output unit based on the transmission characteristic; an imaging unit that images light transmitted through or reflected by the optical filter and outputs first image data, and also images light output from the light output unit that reaches the optical filter without passing through the optical filter and outputs second image data; and an analysis unit that executes a first process to derive wavelength information of the light output from the light output unit based on the first image data and the second image data.

2. 1. A method for testing a photonic integrated circuit having at least one optical output and a waveguide, comprising: Controlling operation of the photonic integrated circuit; an optical filter having a transmission characteristic in which a transmittance changes linearly in a predetermined wavelength range transmits or reflects the light guided by the waveguide and output from the at least one optical output unit based on the transmission characteristic; capturing an image of light transmitted through or reflected by the optical filter and outputting first image data; capturing an image of light that is output from the light output unit and reaches the image sensor without passing through the optical filter, and outputting second image data; and deriving wavelength information of the light output from the light output unit based on the first image data and the second image data.

Images