Optical pulse measuring instrument, optical pulse measurement method, and optical pulse measurement program

Abstract

To provide an optical pulse meter which can reduce a measurement time.SOLUTION: An optical pulse meter 100 comprises: a wavelength variable filter 13 capable of successively changing the transmission wavelength band of first light to be measured that is branched from light to be measured; an optical detector array 14 made by arranging, in array form along a region, a plurality of optical detectors to which first light to be measured having passed through the wavelength variable filter 13 and second light to be measured having been branched from the light to be measured and not having passed through the wavelength variable filter enter, and which output a photocurrent obtained based on exponential strength of light at a plurality of positions in a region where the first light to be measured and the second light to be measured optically overlap; a generation unit 501 for generating a spectrogram on the basis of a photocurrent that corresponds to the transmission wavelength band set by the wavelength variable filter 13 and the position of the region; and an identification unit 502 for identifying the amplitude and phase of the light to be measured, on the basis of the spectrogram generated by the generation unit 501.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an optical pulse measuring device, an optical pulse measuring method, and an optical pulse measuring program.

Background Art

[0002] In the field of optical communication or optical measurement, high-speed optical pulse signals are handled, and the pulse width of optical pulses is 100 ps or less, and in the case of high-speed ones, it reaches 10 ps or less. With the increase in the speed of optical communication or optical measurement, the demand for measuring optical pulses of 10 ps or less is increasing. Patent Document 1 discloses a technique related to an optical correlator that increases the operating speed of optical correlation measurement and enables waveform measurement of single optical pulses.

[0003] If the amplitude shape (envelope) and phase of a high-speed short-period optical pulse signal can be measured, the shape of the carrier wave can be grasped, so that the detailed time characteristics of the optical pulse signal can be clarified. When measuring the amplitude shape and phase of an optical pulse signal, a method of analyzing the characteristics of a signal obtained by synthesizing an optical pulse signal that has passed through a predetermined wavelength band of the optical pulse signal to be measured and an optical pulse signal obtained by delaying the optical pulse signal to be measured by a predetermined time is adopted.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present invention has been made in view of the above points, and an object thereof is to provide an optical pulse measuring device, an optical pulse measuring method, and an optical pulse measuring program that can shorten the measurement time as compared with the case of synthesizing an optical pulse signal that has passed through a predetermined wavelength band of the optical pulse signal to be measured and an optical pulse signal obtained by delaying the optical pulse signal to be measured by a predetermined time when measuring an optical pulse. [Means for solving the problem]

[0006] A first aspect of the present invention is an optical pulse measuring instrument comprising a tunable filter capable of continuously changing the transmission wavelength band of a first light to be measured that is branched from the light to be measured, and the first light to be measured that has passed through the tunable filter. From one end The light is branched from the light to be measured and passes through the tunable filter. Without delay from the first light to be measured The second measurement was not performed. Light from the other end It enters, Optical correlation is performed by superimposing the first and second light beams to be measured, which are incident from both ends, in opposite directions of light propagation. A photodetector comprising a plurality of photodetectors arranged in an array along a region where the first light to be measured and the second light to be measured optically overlap, each of which outputs a photocurrent obtained based on the power-law intensity of the light at multiple positions in the region; a generation unit that generates a spectrogram based on the photocurrent corresponding to the transmission wavelength band set by the tunable filter and the position in the region; and a identification unit that identifies the amplitude and phase of the light to be measured based on the spectrogram generated by the generation unit. It is equipped with.

[0007] A second aspect of the present invention is an optical pulse measuring instrument according to the first aspect, wherein the tunable wavelength filter can continuously change the transmission wavelength band according to the temperature.

[0009] A fourth aspect of the present invention is the first aspect. or The 2 status To The optical pulse measuring instrument further comprises a splitter that splits the light to be measured into the first light to be measured and the second light to be measured.

[0010] This invention 4 The embodiment is an optical pulse measurement method, wherein a processor sets the transmission wavelength band of a tunable filter that can continuously change the transmission wavelength band of a first light to be measured that has been branched from the light to be measured, and the first light to be measured that has passed through the tunable filter From one end The light is branched from the light to be measured and passes through the tunable filter. Without delay from the first light to be measured The second measurement was not performed. Light from the other end It enters, Optical correlation is performed by superimposing the first and second light beams to be measured, which are incident from both ends, in opposite directions of light propagation. A spectrogram is generated based on the photocurrent obtained based on the power-law intensity of light at multiple positions in the region where the first light to be measured and the second light to be measured optically overlap, and a process is performed to determine the amplitude and phase of the light to be measured based on the generated spectrogram.

[0011] A fifth aspect of the present invention is an optical pulse measurement program, wherein a computer sets the transmission wavelength band of a tunable filter that can continuously change the transmission wavelength band of a first light to be measured branched from the light to be measured, and the first light to be measured that has passed through the tunable filter From one end The light is branched from the light to be measured and passes through the tunable filter. Without delay from the first light to be measured The second measurement was not performed. Light from the other end It enters, Optical correlation is performed by superimposing the first and second light beams to be measured, which are incident from both ends, in opposite directions of light propagation. A spectrogram is generated based on the photocurrent obtained based on the power-law intensity of light at multiple positions in the region where the first light to be measured and the second light to be measured optically overlap, and a process is performed to determine the amplitude and phase of the light to be measured based on the generated spectrogram. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an optical pulse measuring instrument, an optical pulse measuring method, and an optical pulse measuring program that can shorten the measurement time when measuring an optical pulse compared to the case in which an optical pulse signal transmitted through a predetermined wavelength band of the optical pulse signal to be measured and an optical pulse signal delayed by a predetermined time are combined. [Brief explanation of the drawing]

[0013] [Figure 1] This figure shows a schematic configuration of an optical pulse measuring instrument according to an embodiment of the present invention. [Figure 2] This is a plan view showing an example configuration of a tunable filter. [Figure 3] This is a block diagram showing the hardware configuration of an information processing device. [Figure 4] This is a block diagram showing an example of the functional configuration of an information processing device. [Figure 5] It is a diagram for explaining a method of measuring a measurement pulse by an optical pulse measuring device. [Figure 6] It is a diagram for explaining a method of measuring a measurement pulse by an optical pulse measuring device. [Figure 7] It is a diagram for explaining a method of measuring a measurement pulse by an optical pulse measuring device. [Figure 8] It is a diagram for explaining a method of measuring a measurement pulse by an optical pulse measuring device. [Figure 9] It is a diagram for explaining a method of measuring a measurement pulse by an optical pulse measuring device. [Figure 10] It is a diagram showing an example of a spectrogram generated by a generation unit and an example of the shape of a measurement pulse obtained from the amplitude and phase of a measurement pulse specified by a specifying unit. [Figure 11] It is a diagram showing a specific example of the amplitude and phase of a measurement pulse from a spectrogram. [Figure 12] It is a diagram showing a specific example of the amplitude and phase of a measurement pulse from a spectrogram. [Figure 13] It is a flowchart showing the flow of measurement processing of a measurement pulse by an information processing device.

Embodiments for Carrying Out the Invention

[0014] Hereinafter, an example of an embodiment of the present invention will be described while referring to the drawings. In each of the drawings, the same or equivalent components and parts are given the same reference numerals. Also, the dimensional ratios in the drawings are exaggerated for the convenience of explanation and may be different from the actual ratios.

[0015] Figure 1 is a diagram showing the schematic configuration of the optical pulse measuring instrument according to this embodiment. The optical pulse measuring instrument 100 includes a chip 10 to which the optical pulse to be measured (measurement pulse), which is the light to be measured, is input through an optical fiber cable 1; an amplification unit 20 that amplifies the output of the chip 10 with multiple amplifiers; a multiplexer 30 that combines the outputs of the amplification unit 20; an A / D converter 40 that converts the output of the multiplexer 30 into a digital signal; and an information processing device 50 that determines the characteristics of the measurement pulse using the output of the A / D converter 40.

[0016] The chip 10 includes a splitter 11 that splits the measurement pulse into two, an optical waveguide 12 for propagating the measurement pulse, a tunable filter 13 for transmitting the measurement pulse, and a photodetector array 14 in which multiple photodetectors are arranged in an array. The optical waveguide 12 is formed of a semiconductor material such as silicon, silicon nitride, or indium phosphide, or an insulating material such as SiOx.

[0017] The tunable filter 13 selects and transmits any wavelength of the measurement pulse. In this embodiment, the tunable filter 13 is a tunable filter in which the selected wavelength changes continuously with temperature. Figure 2 is a plan view showing an example of the configuration of the tunable filter 13. As shown in Figure 2, the tunable filter 13 has a loop-shaped optical waveguide 12, and a heater 62 for heating the optical waveguide 12 is provided in contact with the optical waveguide 12. The temperature of the heater 62 is set according to the amount of current flowing through the electrode 61. As the optical waveguide 12 is heated by the heater 62, the wavelength of the measurement pulse selected and transmitted by the tunable filter 13 changes.

[0018] In this embodiment, the tunable filter 13 is a tunable filter whose selected wavelength changes with temperature in order to be small enough to be mounted on the chip 10, but the present invention is not limited to this example. The tunable filter 13 may be a tunable filter whose wavelength is changed electrically or manually. The optical pulse measuring instrument 100 measures the characteristics of the measurement pulse while changing the wavelength selected by the tunable filter 13. Therefore, by using a tunable filter whose wavelength can be changed by changing the temperature, the optical pulse measuring instrument 100 can shorten the measurement time compared to using a tunable filter whose wavelength is changed electrically or manually.

[0019] The photodetector array 14 is an example of the photodetector unit of the present invention. It detects the power-law intensity of light by receiving a measurement pulse that has been split into two by a brancher 11 and performing optical correlation, and detecting the power-law intensity of light with multiple photodetectors arranged in an array. The photodetectors used are configured to output a current corresponding to a power of the light intensity. The number of photodetectors can be any number, such as 32, 64, or 128, depending on the accuracy of the measurement pulse. The photodetector has an n-doped region and a p-doped region formed such that the adjacent portions of both doped regions are on the optical waveguide 12, with a DC voltage source 15 connected to the n-doped region side and a current detector connected to the p-doped region side.

[0020] For example, the photodetector array 14 can use an optical correlator disclosed in Japanese Patent Application Publication No. 2017-32306. The optical correlator disclosed in Japanese Patent Application Publication No. 2017-32306 involves injecting the light to be measured from an optical pulse into a spatial domain, forming an overlapping region where both lights overlap, and performing optical correlation by autocorrelation or crosscorrelation. This overlapping region is detected by multiple photodetectors, and a photocurrent corresponding to the power-law intensity of the light is output.

[0021] By arranging multiple photodetectors in accordance with the overlapping regions of light formed by optical correlation, the spatial distribution of photocurrent detected simultaneously from each photodetector represents the distribution in the overlapping region of light formed by each optical correlation. Furthermore, the photocurrent detected sequentially from each photodetector represents the change in the state of optical correlation at each position in the overlapping region. The distribution of photocurrent in the overlapping region, obtained by accumulating the photocurrents obtained by optical correlation at each position in the overlapping region, allows us to determine the waveform of the light under test from the optical correlation waveform by accumulating the spatial distribution of photocurrents simultaneously detected from each photodetector corresponding to the optical correlation waveform of the light under test.

[0022] In this embodiment, a measurement pulse (an example of the first light to be measured) that has passed through the tunable filter 13 is incident on the photodetector array 14 from one end, and a measurement pulse (an example of the second light to be measured) that has not passed through the tunable filter 13 is incident on the other end. That is, the photodetector array 14 performs optical correlation by superimposing the measurement pulse that has passed through the tunable filter 13 and the measurement pulse that has not passed through the tunable filter 13 in opposite directions of light propagation. Note that both the measurement pulse that has passed through the tunable filter 13 and the measurement pulse that has not passed through the tunable filter 13 may be incident on the photodetector array 14 from the same end.

[0023] The brancher 11, optical waveguide 12, tunable filter 13, and photodetector array 14 are formed, for example, on an SOI substrate. The brancher 11 is composed of, for example, a silicon photonics nanowire waveguide, the optical waveguide 12 is composed of an optical waveguide, and the photodetector array 14 consists of multiple photodetectors formed by integrating multiple pn diodes into the optical waveguide to form a distributed two-photon absorption photodiode.

[0024] The amplification unit 20 consists of multiple amplifiers arranged in parallel. Each amplifier amplifies the output of one photodetector by a predetermined amount and outputs it.

[0025] The multiplexer 30 multiplexes the outputs of each amplifier in the amplification unit 20 and outputs them. The A / D converter 40 converts the analog signal output of the multiplexer 30 into a digital signal.

[0026] The information processing device 50 generates a spectrogram from the output of the A / D converter 40 and measures the characteristics of the measurement pulse by identifying the phase and amplitude of the measurement pulse based on the generated spectrogram. The method for measuring the characteristics of the measurement pulse by the information processing device 50 will be described in detail later.

[0027] The optical pulse measuring instrument 100 according to this embodiment is characterized by being small, lightweight, easy to handle, mechanically robust, and eliminating the need for optical alignment, as it is equipped with a tunable filter 13 and a photodetector array 14 on the chip 10.

[0028] Figure 3 is a block diagram showing the hardware configuration of the information processing device 50.

[0029] As shown in Figure 3, the information processing device 50 includes a CPU (Central Processing Unit) 51, ROM (Read Only Memory) 52, RAM (Random Access Memory) 53, storage 54, input unit 55, display unit 16, and communication interface (I / F) 57. Each component is connected to the others via a bus 59 so that they can communicate with each other.

[0030] The CPU 51 is a central processing unit that executes various programs and controls various parts. Specifically, the CPU 51 reads a program from the ROM 52 or storage 54 and executes the program using the RAM 53 as a working area. The CPU 51 controls each of the above components and performs various calculations according to the program recorded in the ROM 52 or storage 54. In this embodiment, the ROM 52 or storage 54 stores a measurement program for measuring the characteristics of the measurement pulse.

[0031] ROM 52 stores various programs and data. RAM 53 temporarily stores programs or data as a working area. Storage 54 consists of a storage device such as an HDD (Hard Disk Drive), SSD (Solid State Drive), or flash memory, and stores various programs, including the operating system, and various data.

[0032] The input unit 55 includes a pointing device such as a mouse and a keyboard, and is used for various types of input.

[0033] The display unit 56 is, for example, a liquid crystal display and displays various information. The display unit 56 may also function as an input unit 55 by employing a touch panel system.

[0034] The communication interface 57 is an interface for communicating with other devices, and standards such as Ethernet®, FDDI, and Wi-Fi® are used.

[0035] When executing the above measurement program, the information processing device 50 uses the above hardware resources to implement various functions. The functional configuration implemented by the information processing device 50 will now be described.

[0036] Figure 4 is a block diagram showing an example of the functional configuration of the information processing device 50.

[0037] As shown in Figure 4, the information processing device 50 has a functional configuration consisting of a generation unit 501, a specification unit 502, a display unit 503, and a setting unit 504. Each functional configuration is realized by the CPU 51 reading and executing a measurement program stored in the ROM 52 or storage 54.

[0038] The generation unit 501 generates a spectrogram from the output of the A / D converter 40. In this embodiment, the generation unit 501 uses the horizontal axis to represent the position of each photodetector in the photodetector array 14, and the vertical axis to represent the center wavelength λ of the wavelength set by the tunable filter 13.n This generates a spectrogram representing the intensity of the measurement pulse. The spectrogram generated by the generation unit 501 is a spectrogram representing the strength of the photocurrent signal output by the A / D converter 40.

[0039] The identification unit 502 identifies the amplitude and phase of the measurement pulse based on the spectrogram generated by the generation unit 501. Specifically, the identification unit 502 uses a characteristic function obtained by performing a double inverse Fourier transform on the spectrogram and an ambiguity function of the impulse response of a previously acquired tunable filter to perform predetermined calculations on the spectrogram and inversely determine the amplitude and phase of the measurement pulse. A method for determining the amplitude and phase of the measurement pulse based on the spectrogram can be, for example, the method disclosed in Kazuro Kikuchi and Kenji Taira, "Theory of sonogram characterization of optical pulses", IEEE Journal of Quantum Electronics, Volume 37, Issue 4, April 2001.

[0040] The display unit 503 displays information about the measurement pulse whose amplitude and phase have been determined as a result of predetermined calculation processing performed by the identification unit 502. For example, the display unit 503 displays the amplitude, phase, and approximate waveform shape obtained from the amplitude and phase of the measurement pulse as information about the measurement pulse.

[0041] The setting unit 504 sets the wavelength selected by the tunable filter 13. When measuring the measurement pulse with the optical pulse measuring instrument 100, the photocurrent is measured while changing the set wavelength with the tunable filter 13 as described above. The setting unit 504 may change the set wavelength of the tunable filter 13, or a device other than the information processing device 50 may do so.

[0042] Next, the method for measuring the measurement pulse using the optical pulse measuring instrument according to this embodiment will be described.

[0043] Figures 5 to 9 illustrate the measurement method of the measurement pulse using the optical pulse measuring instrument according to this embodiment. Figures 5 to 9 show an example of a graph of the magnitude of the photocurrent detected by each photodetector in the photodetector array 14 when the wavelength set by the wavelength tunable filter 13 is sequentially changed from λ1 to λ5, along with the configuration of the optical pulse measuring instrument. In the graphs shown in Figures 5 to 9, the horizontal axis represents the position of each photodetector in the photodetector array 14 (unit: m), and the vertical axis represents the magnitude of the photocurrent detected by each photodetector (unit: A). The graphs shown in Figures 5 to 9 are examples where the frequency of the carrier wave is modulated within the measurement pulse.

[0044] In the examples shown in Figures 5 to 9, as the wavelength set in the tunable filter 13 is sequentially changed from λ1 to λ5, the peak position of the photocurrent magnitude changes sequentially. Furthermore, in the examples shown in Figures 5 to 9, as the wavelength set in the tunable filter 13 is sequentially changed from λ1 to λ5, the magnitude of the photocurrent peak also changes. In the examples shown in Figures 5 to 9, when the wavelength is λ3, the peak position of the photocurrent magnitude is in the center of the photodetector array 14, and the magnitude of the photocurrent peak is also the largest.

[0045] In this way, when the wavelength is set with the tunable filter 13, the peak position and magnitude of the photocurrent detected by the photodetector array 14 change according to the set wavelength. The information processing device 50 uses the measurement results of the magnitude of the photocurrent obtained in this way to generate a spectrogram in the generation unit 501, with the horizontal axis representing the position of each photodetector in the photodetector array 14 and the vertical axis representing the wavelength set in the tunable filter 13.

[0046] Figure 10 shows an example of a spectrogram generated by the generation unit 501, and an example of the shape of the measurement pulse obtained from the amplitude and phase of the measurement pulse identified by the identification unit 502. As shown in the upper part of Figure 10, the generation unit 501 generates a spectrogram from the measurement result of the magnitude of the photocurrent. The identification unit 502 can then identify the amplitude and phase of the measurement pulse and determine the shape of the carrier wave of the measurement pulse by performing calculation processing on the spectrogram generated by the generation unit 501.

[0047] Figure 11 shows an example of determining the amplitude and phase of a measurement pulse from a spectrogram. Figure 11 shows an example where the chirp coefficient C of the measurement pulse is C=0. Figure 11(a) is the spectrogram generated by the generation unit 501, Figure 11(b) is the amplitude of the measurement pulse determined from the spectrogram by the identification unit 502, and Figure 11(c) is the phase of the measurement pulse determined from the spectrogram by the identification unit 502. Figures 11(b) and (c) show the identification results by the identification unit 502 and the actual amplitude and phase of the measurement pulse.

[0048] As shown in Figure 11(b), the amplitude determination by the identification unit 502 shows that the actual amplitude of the measurement pulse and the amplitude determined by the identification unit 502 match with extremely high accuracy. Furthermore, as shown in Figure 11(c), the phase determination by the identification unit 502 shows that the actual phase of the measurement pulse and the phase determined by the identification unit 502 match with extremely high accuracy within the range where the amplitude can be determined.

[0049] Figure 12 shows an example of determining the amplitude and phase of a measurement pulse from a spectrogram. Figure 12 shows that the chirp coefficient C of the measurement pulse is C = 4 × 10⁻⁶ 23 This is an example of the case where Figure 12(a) is the spectrogram generated by the generation unit 501, Figure 12(b) is the amplitude of the measurement pulse determined from the spectrogram by the identification unit 502, and Figure 12(c) is the phase of the measurement pulse determined from the spectrogram by the identification unit 502. Figures 12(b) and (c) show the identification results by the identification unit 502 and the actual amplitude and phase of the measurement pulse.

[0050] As shown in Figure 12(b), the results of amplitude determination by the identification unit 502 show that the actual amplitude of the measurement pulse and the amplitude determined by the identification unit 502 match with extremely high accuracy. Furthermore, as shown in Figure 12(c), the results of phase determination by the identification unit 502 show that the actual phase of the measurement pulse and the phase determined by the identification unit 502 match with extremely high accuracy within the range in which the amplitude can be determined.

[0051] Next, the operation of the information processing device 50 will be explained.

[0052] Figure 13 is a flowchart showing the flow of measurement pulse measurement processing by the information processing device 50. The CPU 51 reads the measurement program from the ROM 52 or storage 54, loads it into the RAM 53, and executes it, thereby performing the measurement pulse measurement processing.

[0053] First, in step S101, the CPU 51 sets the wavelength to be selected by the tunable filter 13.

[0054] Once the wavelength to be selected by the tunable filter 13 is set, the CPU 51 then acquires the intensity of the photocurrent detected by the photodetector array 14 in step S102.

[0055] After acquiring the intensity of the photocurrent detected by the photodetector array 14, the CPU 51 then determines in step S103 whether there are still wavelengths remaining that need to be set in the measurement processing of the measurement pulse. If the determination in step S103 indicates that there are still wavelengths remaining that need to be set, the CPU 51 returns to step S101 and sets the wavelength selected by the tunable filter 13 again. On the other hand, if the determination in step S103 indicates that there are no wavelengths remaining that need to be set, the CPU 51 then generates a spectrogram in step S104 using the data of the photocurrent intensity detected by the photodetector array 14.

[0056] After generating a spectrogram using the photocurrent intensity data, the CPU 51 then, in step S105, identifies the amplitude and phase of the measurement pulse from the generated spectrogram.

[0057] After identifying the amplitude and phase of the measurement pulse from the spectrogram, the CPU 51 then displays information about the measurement pulse in step S106. For example, the CPU 51 displays the amplitude, phase, and approximate shape of the waveform obtained from the amplitude and phase of the measurement pulse as information about the measurement pulse.

[0058] There is a growing demand for measuring high-speed optical pulses with pulse widths of 100 ps or less, especially 10 ps or less. Measuring the amplitude shape (envelope) and phase of high-speed, short-period optical pulse signals allows for understanding the carrier wave shape, thereby revealing the detailed temporal characteristics of the optical pulse signal. However, when using an oscilloscope for observation, even observing the envelope becomes difficult when the optical pulse signal is short-period. Therefore, specialized equipment is used for observing the waveforms of high-speed optical pulse signals.

[0059] Conventionally, methods for observing the waveform of optical pulse signals include frequency-resolved optical gating (FROG) and SPIDER (Spectral Phase Interferometry for Direct Electric-field Reconstruction). However, the measurement equipment using these methods is large, cumbersome, and mechanically fragile. Furthermore, while precise alignment is required during measurement, the equipment suffers from low sensitivity.

[0060] In contrast, the optical pulse measuring instrument 100 according to this embodiment differs from conventional optical pulse signal measuring devices in that the photodetector array 14 is integrated into the chip 10, making it compact and lightweight, and enabling optical pulse measurement regardless of the measurement location. Furthermore, because the photodetector array 14 is integrated into the chip 10, the optical pulse measuring instrument 100 according to this embodiment is solid-state, mechanically robust, and does not require optical alignment. Moreover, because the measurement pulse is concentrated in a minute area, the optical pulse measuring instrument 100 according to this embodiment enables highly sensitive measurement. In addition, because the optical pulse measuring instrument 100 according to this embodiment does not require delayed scanning, the measurement time of the measurement pulse can be shortened compared to measurement methods that require delayed scanning.

[0061] In addition, the measurement processing of the measurement pulse, which is executed by the CPU after reading the software (program) in each of the above embodiments, may be executed by various processors other than the CPU. Examples of such processors include PLDs (Programmable Logic Devices) such as FPGAs (Field-Programmable Gate Arrays) whose circuit configuration can be changed after manufacturing, and dedicated electrical circuits that are processors with circuit configurations specifically designed to execute specific processing, such as ASICs (Application Specific Integrated Circuits). Furthermore, the measurement processing of the measurement pulse may be executed by one of these various processors, or by a combination of two or more processors of the same or different types (for example, multiple FPGAs, and a combination of a CPU and an FPGA). More specifically, the hardware structure of these various processors is an electrical circuit that combines circuit elements such as semiconductor elements.

[0062] Furthermore, while the above embodiments describe a configuration in which the program for measuring the measurement pulse is pre-stored (installed) in ROM or storage, the invention is not limited to this. The program may be provided in a form recorded on a non-transitory recording medium such as a CD-ROM (Compact Disk Read Only Memory), DVD-ROM (Digital Versatile Disk Read Only Memory), or USB (Universal Serial Bus) memory. Alternatively, the program may be provided in a form that can be downloaded from an external device via a network. [Explanation of symbols]

[0063] 1. Fiber optic cable 10 chips 11. Turnout 12 Optical waveguide 13. Tunable filter 14 Photodetector Array 20 Amplification section 30 Multiplexer 40 A / D converters 50 Information Processing Devices 100 Light pulse measuring instruments

Claims

1. A tunable wavelength filter that can continuously change the transmission wavelength band of the first light to be measured, which is branched from the light to be measured, A photodetector comprises a photodetector that receives the first light to be measured, which has passed through the tunable filter, from one end, and a second light to be measured, which is branched from the light to be measured, does not pass through the tunable filter, and is not delayed from the first light to be measured, from the other end, and performs optical correlation by superimposing the first light to be measured and the second light to be measured, which have been received from both ends, in the opposite direction of light propagation, and outputs a photocurrent obtained based on the power-law intensity of light at multiple positions in the region in which the first light to be measured and the second light to be measured optically overlap, and multiple photodetectors arranged in an array along the region, A generation unit that generates a spectrogram based on the photocurrent corresponding to the transmission wavelength band set by the tunable filter and the position of the region, A specification unit that identifies the amplitude and phase of the light to be measured based on the spectrogram generated by the generation unit, A light pulse measuring instrument equipped with the following features.

2. The optical pulse measuring instrument according to claim 1, wherein the wavelength-tunable filter can continuously change the transmission wavelength band according to the temperature.

3. The optical pulse measuring instrument according to claim 1 or claim 2, further comprising a splitter for splitting the light to be measured into the first light to be measured and the second light to be measured.

4. The processor, The transmission wavelength band of a tunable filter that can continuously change the transmission wavelength band of the first light to be measured, which is branched from the light to be measured, is set. The first light to be measured, having passed through the tunable filter, is incident from one end, and the second light to be measured, branched from the light to be measured, not passing through the tunable filter, and not delayed from the first light to be measured, is incident from the other end. Optical correlation is performed by superimposing the first and second light to be measured incident from both ends in opposite directions of light propagation, and a spectrogram is generated based on the photocurrent obtained based on the power-law intensity of light at multiple positions in the region where the first and second light to be measured optically overlap. The amplitude and phase of the light being measured are determined based on the generated spectrogram. A method for measuring optical pulses to perform processing.

5. On the computer, The transmission wavelength band of a tunable filter that can continuously change the transmission wavelength band of the first light to be measured, which is branched from the light to be measured, is set. The first light to be measured, having passed through the tunable filter, is incident from one end, and the second light to be measured, branched from the light to be measured, not passing through the tunable filter, and not delayed from the first light to be measured, is incident from the other end. Optical correlation is performed by superimposing the first and second light to be measured incident from both ends in opposite directions of light propagation, and a spectrogram is generated based on the photocurrent obtained based on the power-law intensity of light at multiple positions in the region where the first and second light to be measured optically overlap. The amplitude and phase of the light being measured are determined based on the generated spectrogram. A program that performs light pulse measurement and executes processing.

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