Testing device for acousto-optic integrated chip

Abstract

According to the testing device of the acousto-optic integrated chip, the heat dissipation capability of the testing device is enhanced by adopting an advanced printed circuit board (PCB) manufacturing process, so that the temperature fluctuation in the chip testing process is reduced, a laser in the device serves as an input light source of the acousto-optic integrated chip in combination with a spatial optical coupling technology, and the assembling process before testing is remarkably reduced. The testing device provided by the invention can carry out rapid, accurate and lossless performance testing on the acousto-optic integrated chip, can be compatible with the testing requirement of a bare chip before packaging, is simple in structure and high in integration degree, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of acousto-optic chips, and relates to a chip testing device. BACKGROUND

[0002] An acousto-optic integrated chip is a kind of device in which acoustic waves and optical waves interact on a chip, and contains an acousto-optic modulator, an acousto-optic frequency shifter, an acousto-optic deflector, an acousto-optic filter and an acousto-optic Q switch, and can realize conversion and fine control of acoustic signals and optical signals. By combining the advantages of electromagnetic interference resistance, cross-medium transmission characteristics and large-capacity information transmission of acoustic waves and optical waves, the acousto-optic integrated chip has broad application prospects in the fields of laser radar, satellite communication and intelligent sensing.

[0003] The development of the acousto-optic integrated chip industry requires accurate, reliable and rapid testing of the performance of the chip. However, the current performance testing means mainly follows the testing method of traditional microelectronic technology, lacks targeted design for acousto-optic integrated chips, and has the following defects. Firstly, the heat dissipation capacity of the testing device is poor, and it is difficult to weaken or compensate for the temperature drift phenomenon existing in the acousto-optic integrated chip, so that the reliability of the test result is insufficient; secondly, most of them are only suitable for testing packaged chips, and lack non-destructive testing means for pre-packaging bare chips; and thirdly, the testing efficiency is low, and it is difficult to meet the batch production demand. SUMMARY

[0004] In view of the deficiencies of the prior art, the application provides a testing device for an acousto-optic integrated chip. By using an advanced printed circuit board (PCB) manufacturing process and combining spatial light coupling technology, rapid, non-destructive and accurate detection of the acousto-optic integrated chip is realized. The application has simple structure, high device integration and broad application prospects.

[0005] The application provides the following technical solutions:

[0006] A testing device for an acousto-optic integrated chip, comprising a to-be-tested chip, a printed circuit board, a laser, a radio frequency electric controller and a mounting base, wherein an interdigital transducer array is prepared on the upper surface of the to-be-tested chip, the interdigital transducer array is connected with the radio frequency electric controller, the to-be-tested chip, the laser and the radio frequency electric controller are surface-mounted on the upper surface of the printed circuit board, and the printed circuit board is mounted on the mounting base by fixing screws.

[0007] The to-be-tested chip is characterized in that the chip is a bare chip that has not been packaged and is directly fixed on the printed circuit board by surface mounting technology.

[0008] The laser is characterized in that the laser output is coupled into the waveguide of the to-be-tested chip through a spatial light coupler, the wavelength of the light is 0.5-2 microns, non-contact optical connection is realized, and physical damage to the chip is avoided.

[0009] The printed circuit board is characterized in that high-thermal-conductivity materials (such as gold) are embedded in specific parts (such as below the interdigital transducer array and the laser) of the printed circuit board. The heat generated by the chip during operation is quickly conducted away through the high thermal conductivity of the materials, which can effectively suppress the temperature drift effect of the integrated acousto-optic chip during the test process, and significantly improve the reliability of the test data.

[0010] Further, the high-thermal-conductivity materials embedded in the printed circuit board are copper, silver, gold, or diamond, and other materials with a thermal conductivity higher than 200 W / (m·K).

[0011] Further, the printed circuit board contains 2-10 layers of conductive metal, with a thickness of 1-12 mm.

[0012] Further, the printed circuit board is provided with a structure for directional reflection or elimination of acoustic wave reflection around the edge of the chip to be tested.

[0013] The radio frequency electric controller is characterized in that the substrate material is ceramic, the internal connection traces meet the 50-ohm impedance matching condition, and the transmission reflection between the load impedance and the source internal impedance is minimal, thereby realizing maximum power transmission.

[0014] The radio frequency electric controller is characterized in that it is equipped with a radio frequency phase shifter and a radio frequency amplifier, which can respectively realize phase control and power control of the radio frequency signal, meeting various testing needs.

[0015] Preferably, the radio frequency electric controller outputs a radio frequency electric signal with a frequency of 100 MHz-10 GHz and a power of 0.1-30 dBm.

[0016] Preferably, the radio frequency electric controller outputs an electric signal with a frequency range of 0.1-40 GHz.

[0017] Preferably, the radio frequency electric controller contains a phase shifter that is digitally controlled and can apply a phase shift value ranging from 1 to 359° to the electric signal of multiple channels.

[0018] The interdigital transducer array is characterized in that it adopts a detachable electrical connection mode (such as wire bonding) with the radio frequency electric controller. During testing, the chip to be tested can be quickly switched by changing the cut-off wire.

[0019] Compared with the prior art, the advantages of the present application include:

[0020] 1. The device has a certain passive heat dissipation capacity, which can efficiently dissipate the heat generated by the integrated acousto-optic chip during operation, thereby effectively reducing the temperature fluctuation of the chip during the test process and ensuring the test reliability.

[0021] 2. The use of the device for testing will not cause damage to the chip, and the chip can still be used after disassembly

[0022] 3. The replacement step of the to-be-tested chip is simple, and the lead can be replaced by cutting, thereby greatly improving the test efficiency to meet the industrialization batch detection demand;

[0023] 4. The bare chip before packaging can be tested, compared with the chip after packaging, the test for the bare chip before packaging can find the quality problems existing therein earlier, which is beneficial to reduce economic loss.

[0024] The application is especially suitable for research and development verification and mass production quality inspection of acousto-optic integrated chips such as acousto-optic modulators and acousto-optic deflectors, and has high integration, low cost and industrial application value. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a structural schematic diagram of the test device of the acousto-optic integrated chip of the application.

[0026] Figure 2 is a use instruction diagram of the test device of the acousto-optic integrated chip of the application.

[0027] Figure 1 Reference signs:

[0028] 1, to-be-tested chip: the to-be-tested object of the test device proposed in the application, 101, interdigital transducer array: realizing conversion of electrical signal and acoustic signal, located above the to-be-tested chip, connected with an external radio frequency driving circuit;

[0029] 2, printed circuit board: used for bearing the acousto-optic to-be-tested chip and the laser, 201, metal embedded in the circuit board: by embedding high thermal conductivity material in the specific part of the circuit board, the passive heat dissipation capacity of the test device is enhanced;

[0030] 3, laser: providing optical signal input for the acousto-optic to-be-tested chip, and feeding the output light into the to-be-tested chip through an optical coupler;

[0031] 4, radio frequency electric controller: providing specific radio frequency signal for the interdigital transducer according to the test requirement, 401, radio frequency phase shifter: numerically controlling the phase shift of the input radio frequency signal according to the test requirement, 402, radio frequency amplifier: amplifying the radio frequency signal after phase shift to drive the interdigital transducer;

[0032] 5, mounting base.

[0033] Figure 2 Reference signs:

[0034] I, direct current signal generator: providing required direct current input for the laser, radio frequency amplifier and the like in the device;

[0035] Ⅱ, external laser: if the laser in the device cannot provide the required optical signal, an external laser can be used as the optical input of the test device;

[0036] Ⅲ, RF signal generator: provides RF signal input for the acousto-optic chip test device;

[0037] Ⅳ, acousto-optic chip test device: the acousto-optic chip test device described in the present application;

[0038] Ⅴ, thermal imager: monitor the temperature change of the acousto-optic chip;

[0039] Ⅵ, spectrometer: directly measure the output optical signal of the chip under test;

[0040] Ⅶ, fiber amplifier: amplify the output optical signal of the chip under test for fine measurement and analysis;

[0041] Ⅷ, photodetector: convert the output optical signal into an electrical signal;

[0042] Ⅸ, vector network analyzer: used to measure link loss and other indicators; DETAILED DESCRIPTION

[0043] The technical solutions in the embodiments of the present application will be described in detail below with reference to the drawings in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0044] Case 1

[0045] Please refer to Figure 1 If the device proposed in the present application is used to test the acousto-optic deflector chip. The acousto-optic deflector chip refers to a device that controls the deflection direction of the light beam through acoustic signals. The working process of the test device is as follows:

[0046] The laser emitted by the laser (3) is coupled into the acousto-optic chip (1) under test after passing through the optical coupler.

[0047] The RF signal is input to the RF electric controller (4), which is processed by the RF phase shifter (401) and the RF amplifier (402), and then loaded onto the interdigital transducer array (101). Through the inverse piezoelectric effect, the interdigital transducer array (101) generates acoustic surface waves that spread on the surface of the acousto-optic chip (1). The acoustic surface waves generate an equivalent acousto-optic grating on the surface layer of the chip, causing the incident light to be deflected. The deflection angle is related to the frequency of the RF signal.

[0048] Please refer to Figure 2The application provides a sound-light deflection chip test scheme, which uses a spectrometer, a direct current signal generator and the like instruments and meters. Indexes including but not limited to deflection efficiency, resolution, response time, extinction ratio, modulation bandwidth, thermal stability and the like can be detected. The specific operation method is as follows:

[0049] The sound-light integrated chip test device (IV) provided by the application is used, the chip to be tested is mounted on a printed circuit board in a surface mounting manner, the test device is connected to a direct current signal generator (I), power supply for a laser and a radio frequency electric controller in the device is provided, and the laser is driven to output laser. The laser is input into the sound-light deflection chip to be tested through a spatial light coupler. Coupling with the sound wave excited by the interdigital transducer array occurs, thereby diffraction occurs, and the outgoing light is emitted at a certain angle. The outgoing light is captured by a spectrometer (VI).

[0050] By measuring the intensity of the outgoing light and comparing with the intensity of the incident light, the deflection efficiency of the sound-light deflection device can be calculated.

[0051] The resolution of the sound-light deflection device can be calculated by driving the frequency ladder to change and recording the angle interval of the adjacent light spots when the light spots are just separated by the spectrometer.

[0052] The response time of the sound-light deflection device can be calculated by detecting the time when the light beam is stabilized to the new position after the radio frequency signal changes.

[0053] The extinction ratio of the sound-light deflection device can be calculated by detecting the light intensity when the sound-light deflection device works at the frequency and the light intensity when the same position has no radio frequency signal input.

[0054] The modulation bandwidth of the sound-light deflection device can be calculated by scanning the radio frequency signal frequency and simultaneously monitoring the lowest frequency and the highest frequency at which the diffraction efficiency is greater than 50%.

[0055] The temperature change of the sound-light deflection chip to be tested in the test process can be monitored by a thermal imager (V), the light spot position drift on the spectrometer can be detected by detecting the continuous incidence of the high-power laser, and the thermal stability of the sound-light integrated chip can be obtained.

[0056] Case two

[0057] Please refer to Figure 1 If the device provided by the application is used to test a sound-light modulation chip. The sound-light modulation chip modulates the light signal intensity through a sound signal, and the working process of the test device is as follows:

[0058] The laser emitted by the laser is coupled into the sound-light chip to be tested after passing through the optical coupler.

[0059] The radio frequency signal is input into a radio frequency electric controller, and after being processed by a radio frequency phase shifter and a radio frequency amplifier, is loaded onto the interdigital transducer array, and through the action of the inverse piezoelectric effect, the interdigital transducer array generates a surface acoustic wave that spreads on the surface of the acousto-optic chip. The surface acoustic wave generates an equivalent acousto-optic grating on the surface layer of the chip, so that the intensity of the incident light changes. The change in the light intensity is related to the power of the radio frequency signal.

[0060] Referring back to Figure 2 The present application provides an acousto-optic modulation chip test scheme, using a spectrometer, a vector network analyzer and other instruments. It can detect indicators including but not limited to diffraction efficiency, extinction ratio, rise / fall time, modulation bandwidth, modulation depth, insertion loss, modulation half-wave voltage, etc. The specific operation method is as follows:

[0061] The acousto-optic integrated chip test device (IV) provided by the present application is used. The chip to be tested is mounted on a printed circuit board by surface mounting. The test device is connected to a direct current signal generator (I) to provide power for the laser and the radio frequency electric controller in the device, and to drive the laser to output laser. The laser is input into the acousto-optic modulation chip to be tested through a spatial light coupler. The acoustic wave excited by the interdigital transducer array is coupled, and diffraction occurs, so that light with a certain intensity is emitted. After the emitted light is amplified by a fiber amplifier (VII), it is introduced into a photodetector (VIII), and the optical signal is converted into an electrical signal, which is input into a vector network analyzer (IX) and compared with the signal input by the radio frequency electric controller (III).

[0062] By measuring the optical power of the target diffraction order and the optical power after blocking other light paths, the diffraction efficiency of the acousto-optic modulation device can be calculated.

[0063] By detecting the light intensity at the resonant frequency and the background light intensity at the same position after the radio frequency drive is turned off, the extinction ratio of the acousto-optic modulation device can be calculated.

[0064] The acousto-optic modulation device is driven by a square wave radio frequency signal, and the transient response waveform of the diffraction light intensity is captured, and the edge time is directly read, so that the rise / fall time can be calculated.

[0065] The input light intensity is fixed, and the radio frequency signal is swept, so that the modulation bandwidth of the acousto-optic modulation device can be calculated.

[0066] The sinusoidal radio frequency signal is input, and the AC component and DC component of the diffraction light intensity are detected, so that the modulation depth of the acousto-optic modulation device can be calculated.

[0067] By comparing the reference optical power with the transmission optical power after the radio frequency signal input is turned off, the insertion loss of the acousto-optic modulation device can be calculated.

[0068] The input DC signal drives the acousto-optic modulation device, the DC signal is adjusted, the corresponding light intensity is detected, and the difference between the DC voltages corresponding to the adjacent maximum and minimum values is the half-wave voltage.

Claims

1. A testing device integrating an acousto-optic chip, characterized in that, The device includes a chip under test (1), a printed circuit board (2), a laser (3), an RF controller (4), and a mounting base (5). The chip under test has an interdigital transducer (IDT) array (101) that can generate acoustic waves. The printed circuit board is used for chip mounting and DC signal input. The laser is mounted on the printed circuit board to provide optical input to the chip under test. The RF controller is used to provide the RF signal required for the interdigital transducer to operate. The mounting base provides physical support for the components mentioned above.

2. The testing device for the integrated acousto-optic chip according to claim 1, characterized in that, The printed circuit board is surface-mounted with a chip under test (DUT), a laser, and a spatial optical coupler. The laser is driven by DC power and the emitted laser light is input to the DUT via spatial optical coupling. The printed circuit board is manufactured using an embedded metal process, with 2 to 10 conductive layers and a thickness of 1 to 12 mm. It contains highly thermally conductive material to efficiently dissipate the heat generated by the DUT during operation. The printed circuit board has a structure for directional reflection or elimination of sound wave reflection around the edge of the DUT.

3. The testing device for the integrated acousto-optic chip according to claim 1, characterized in that, The radio frequency controller is electrically connected to each IDT via gold wires or gold strips, applying electrical signals of specific frequency, phase, and amplitude to the IDT. The radio frequency controller includes a phase shifter to change the phase of the electrical signal; it also includes a power amplification unit to amplify the power of the output electrical signal. The electrical controller is equipped with an RF connector, which can be connected to an external RF source meter.

4. The testing device for the integrated acousto-optic chip according to claim 2, characterized in that, The area containing high thermal conductivity material embedded inside the printed circuit board is located directly below the chip under test (IDT) (i.e., along the chip normal, towards the mounting base). The upper surface of this area is in close contact with the lower surface of the chip under test to improve the efficiency of heat dissipation.

5. The testing device for the integrated acousto-optic chip according to claim 2, characterized in that, The high thermal conductivity material embedded inside the printed circuit board is specifically copper, silver, gold, diamond, or other materials with a thermal conductivity higher than 200 W / (m·K).

6. The testing apparatus for the integrated acousto-optic chip according to claim 3, characterized in that, The radio frequency electrical signal output by the radio frequency controller has a frequency of 100MHz to 10GHz and a power of 0.1 to 30dBm.

7. The testing apparatus for the integrated acousto-optic chip according to claim 3, characterized in that, The radio frequency controller includes a digitally controlled phase shifter that can apply a phase shift value ranging from 1 to 359° to multiple channels of electrical signals.

8. The testing apparatus for integrated acousto-optic chips according to claim 3, characterized in that, The substrate material of the radio frequency controller is ceramic, and the circuit topology is set according to a 50Ω impedance matching.

9. The testing apparatus for an integrated acousto-optic chip according to claim 2, characterized in that, The printed circuit board is equipped with a spatial optical coupler, which can couple the light output from the laser into the waveguide of the chip under test, with a light wavelength of 0.5 to 2 μm.

10. The testing apparatus for the integrated acousto-optic chip according to claim 1, characterized in that, The chip under test is an unpackaged bare chip.

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