CN114112319A - Laser instrument test system - Google Patents
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- CN114112319A CN114112319A CN202110637693.5A CN202110637693A CN114112319A CN 114112319 A CN114112319 A CN 114112319A CN 202110637693 A CN202110637693 A CN 202110637693A CN 114112319 A CN114112319 A CN 114112319A
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Abstract
The application provides a laser instrument test system for the high frequency capability test of the laser device that awaits measuring includes: the signal detection device comprises a first signal output end, a second signal output end and a signal receiving end, a test signal is transmitted to the laser device to be tested through the first signal output end and the second signal output end, and an optical signal generated by the laser device to be tested is received through the signal receiving end; the input end of the biaser is connected with the first signal output end, and the output end of the biaser is used for outputting a test signal loaded with a bias signal; a DC power supply for supplying power to the biaser; and the input end of the matching circuit is connected with the output end of the biaser and the second signal output end, and the output end of the matching circuit is used for connecting the laser device to be tested. The laser testing system provided by the application avoids the serious impedance adaptation between the laser device to be tested and the signal transmission line of the testing system, and is convenient for ensuring the accuracy of the high-frequency performance test of the laser device to be tested.
Description
Technical Field
The application relates to the technical field of optical communication, in particular to a laser testing system.
Background
The application markets of big data, block chains, cloud computing, internet of things, artificial intelligence and the like are rapidly developed, explosive growth is brought to data traffic, and the optical communication technology has gradually replaced traditional electrical signal communication in various industry fields due to the advantages of high unique speed, high bandwidth, low erection cost and the like. The semiconductor laser chip is a key device in modern optical fiber communication products, realizes the population inversion of non-equilibrium carriers between energy bands (conduction band and valence band) of semiconductor substances or between the energy bands of the semiconductor substances and energy levels of impurities (acceptor or donor) through a certain excitation mode, and generates stimulated emission when a large number of electrons in a population inversion state are compounded with holes, thereby generating laser.
In order to meet the continuously increasing bandwidth requirement, optoelectronic devices are continuously updated and iterated, and a high-speed dfb (distributed feedback laser) semiconductor laser chip belongs to an edge-emitting laser. However, when the laser chip is applied to an optical fiber communication product, the laser chip is generally required to be packaged into a laser device through a packaging structure, for example, the laser chip is attached to a ceramic substrate, and the laser chip is bonded to an RF circuit or the like of the substrate through a gold wire, so as to achieve interconnection between the laser chip and the ceramic substrate. Furthermore, the high-frequency response of the laser chip and the package structure jointly determines the high-frequency modulation performance of the laser device, so that the package structure is very important for the performance of high bandwidth and ultrahigh bandwidth, and becomes an important technical barrier influencing the performance of high-speed optical communication.
The laser device with excellent high-speed performance can obviously improve the key performance index and competitiveness of the product, however, any impedance mismatch or resonance effect can seriously deteriorate the performance of the whole product, so that the laser device cannot realize high-speed application, and therefore, the performance of the laser device in an optical communication product is ensured to be necessary. At present, in order to ensure the performance of a laser device in an optical communication product, a high-frequency performance test is usually used to select a laser device with a high-frequency performance meeting the requirement. Therefore, how to more accurately test the high-frequency performance of the laser device is a technical problem to be solved by those skilled in the art.
Disclosure of Invention
The embodiment of the application provides a laser device testing system which is convenient for accurately testing the high-frequency performance of a laser device.
The application provides a laser instrument test system for the high frequency capability test of the laser device that awaits measuring includes:
the signal detection device comprises a first signal output end, a second signal output end and a signal receiving end, a test signal is transmitted to the laser device to be tested through the first signal output end and the second signal output end, and an optical signal generated by the laser device to be tested is received through the signal receiving end;
the input end of the biaser is connected with the first signal output end, and the output end of the biaser is used for outputting a test signal loaded with a bias signal;
a DC power supply for supplying power to the biaser;
and the input end of the matching circuit is connected with the output end of the biaser and the second signal output end, and the output end of the matching circuit is used for connecting the laser device to be tested.
According to the laser testing system, one path of testing signals of the signal detection device are transmitted to the biaser, the biasing signals are loaded through biasing conversion of the biaser and then transmitted to the matching circuit, the other path of testing signals of the signal detection device are directly transmitted to the matching circuit and then transmitted to the laser device to be tested through the matching circuit respectively, the laser device to be tested generates optical signals according to the received testing signals, the generated optical signals are transmitted to the signal detection device finally, and the signal detection device determines the high-frequency performance of the laser device to be tested according to the received optical signals. In the laser testing system provided by the application, the matching circuit is arranged to realize impedance matching between the packaging structure of the laser device to be tested and the signal transmission line of the testing system, so that the serious impedance matching between the laser device to be tested and the signal transmission line of the testing system is avoided, and the accuracy of the high-frequency performance test of the laser device to be tested is ensured.
Drawings
In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without any creative effort.
Fig. 1 is a schematic diagram of a connection relationship of an optical communication terminal;
fig. 2 is a schematic structural diagram of an optical network terminal;
fig. 3 is a schematic structural diagram of an optical module according to an embodiment of the present disclosure;
FIG. 4 is a schematic diagram of an exploded structure of an optical module according to an embodiment of the present application;
fig. 5 is a schematic diagram of an internal structure of an optical module according to an embodiment of the present disclosure;
fig. 6 is a schematic diagram of an tosa according to an embodiment of the present disclosure;
FIG. 7 is a schematic diagram illustrating a separated stem and cap structure of a light emitting module according to an embodiment of the present disclosure;
fig. 8 is a schematic structural diagram of a laser device according to an embodiment of the present disclosure;
fig. 9 is an equivalent structural diagram of a laser device according to an embodiment of the present application;
fig. 10 is a first usage state diagram of a laser testing system according to an embodiment of the present disclosure;
fig. 11 is a schematic structural diagram of a laser device and a matching circuit according to an embodiment of the present disclosure;
fig. 12 is a second usage state diagram of a laser testing system according to an embodiment of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
One of the core links of optical fiber communication is the interconversion of optical and electrical signals. The optical fiber communication uses optical signals carrying information to transmit in information transmission equipment such as optical fibers/optical waveguides, and the information transmission with low cost and low loss can be realized by using the passive transmission characteristic of light in the optical fibers/optical waveguides; meanwhile, the information processing device such as a computer uses an electric signal, and in order to establish information connection between the information transmission device such as an optical fiber or an optical waveguide and the information processing device such as a computer, it is necessary to perform interconversion between the electric signal and the optical signal.
The optical module realizes the function of interconversion of optical signals and electrical signals in the technical field of optical fiber communication, and the interconversion of the optical signals and the electrical signals is the core function of the optical module. The optical module is electrically connected with an external upper computer through a golden finger on an internal circuit board of the optical module, and the main electrical connection comprises power supply, I2C signals, data signals, grounding and the like; the electrical connection mode realized by the gold finger has become the mainstream connection mode of the optical module industry, and on the basis of the mainstream connection mode, the definition of the pin on the gold finger forms various industry protocols/specifications.
Fig. 1 is a schematic diagram of connection relationship of an optical communication terminal. As shown in fig. 1, the connection of the optical communication terminal mainly includes the interconnection among the optical network terminal 100, the optical module 200, the optical fiber 101 and the network cable 103;
one end of the optical fiber 101 is connected with a far-end server, one end of the network cable 103 is connected with local information processing equipment, and the connection between the local information processing equipment and the far-end server is completed by the connection between the optical fiber 101 and the network cable 103; and the connection between the optical fiber 101 and the network cable 103 is made by the optical network terminal 100 having the optical module 200.
An optical port of the optical module 200 is externally accessed to the optical fiber 101, and establishes bidirectional optical signal connection with the optical fiber 101; an electrical port of the optical module 200 is externally connected to the optical network terminal 100, and establishes bidirectional electrical signal connection with the optical network terminal 100; the optical module realizes the interconversion of optical signals and electric signals, thereby realizing the establishment of information connection between the optical fiber and the optical network terminal; specifically, the optical signal from the optical fiber is converted into an electrical signal by the optical module and then input to the optical network terminal 100, and the electrical signal from the optical network terminal 100 is converted into an optical signal by the optical module and input to the optical fiber.
The optical network terminal is provided with an optical module interface 102, which is used for accessing an optical module 200 and establishing bidirectional electric signal connection with the optical module 200; the optical network terminal is provided with a network cable interface 104, which is used for accessing the network cable 103 and establishing bidirectional electric signal connection with the network cable 103; the optical module 200 is connected to the network cable 103 through the optical network terminal 100, specifically, the optical network terminal transmits a signal from the optical module to the network cable and transmits the signal from the network cable to the optical module, and the optical network terminal serves as an upper computer of the optical module to monitor the operation of the optical module.
At this point, a bidirectional signal transmission channel is established between the remote server and the local information processing device through the optical fiber, the optical module, the optical network terminal and the network cable.
Common information processing apparatuses include routers, switches, electronic computers, and the like; the optical network terminal is an upper computer of the optical module, provides data signals for the optical module, and receives the data signals from the optical module, and the common upper computer of the optical module also comprises an optical line terminal and the like.
Fig. 2 is a schematic diagram of an optical network terminal structure. As shown in fig. 2, the optical network terminal 100 has a circuit board 105, and a cage 106 is disposed on a surface of the circuit board 105; an electric connector is arranged in the cage 106 and used for connecting an electric port of an optical module such as a golden finger; the cage 106 is provided with a heat sink 107, and the heat sink 107 has a projection such as a fin that increases a heat radiation area.
The optical module 200 is inserted into the optical network terminal, specifically: the electrical port of the optical module is inserted into an electrical connector inside the cage 106, and the optical port of the optical module is connected to the optical fiber 101.
The cage 106 is positioned on the circuit board, and the electrical connector on the circuit board is wrapped in the cage, so that the electrical connector is arranged in the cage; the optical module is inserted into the cage, held by the cage, and the heat generated by the optical module is conducted to the cage 106 and then diffused by the heat sink 107 on the cage.
The fifth generation mobile communication technology (5G) currently meets the current growing demand for high-speed wireless transmission. The frequency spectrum adopted by the 5G communication is much higher than that adopted by the 4G communication, which brings a greatly improved communication rate for the 5G communication, but the transmission attenuation of the signal is relatively obviously increased.
The new service characteristics and higher index requirements of 5G provide new challenges for the bearer network architecture and each layer of technical solutions, wherein the optical module serving as a basic constituent unit of the physical layer of the 5G network also faces technical innovation and upgrade, which is mainly reflected in that the optical module applied to 5G transmission needs to have two basic technical characteristics of high-speed transmission and low return loss. In order to meet the requirement of an optical module in a 5G communication network, an embodiment of the present application provides an optical module.
Fig. 3 is a schematic diagram of an optical module according to an embodiment of the present disclosure, and fig. 4 is an exploded schematic diagram of an optical module according to an embodiment of the present disclosure. As shown in fig. 3 and 4, an optical module 200 provided in the embodiment of the present application includes an upper housing 201, a lower housing 202, a circuit board 203, a circular-square tube 300, a light emitting module 400, and a light receiving module 500.
The upper shell 201 is covered on the lower shell 202 to form a wrapping cavity with two openings; the outer contour of the wrapping cavity is generally a square body, and specifically, the lower shell comprises a main plate and two side plates which are positioned at two sides of the main plate and are perpendicular to the main plate; the upper shell comprises a cover plate, and the cover plate covers two side plates of the upper shell to form a wrapping cavity; the upper shell can also comprise two side walls which are positioned at two sides of the cover plate and are perpendicular to the cover plate, and the two side walls are combined with the two side plates to realize that the upper shell covers the lower shell.
The two openings may be two ends (204, 205) in the same direction, or two openings in different directions; one opening is an electric port 204, and a gold finger of the circuit board extends out of the electric port 204 and is inserted into an upper computer such as an optical network terminal; the other opening is an optical port 205 for external optical fiber access; the photoelectric devices such as the circuit board 203, the round and square tube 300, the light emitting module 400 and the light receiving module 500 are positioned in the packaging cavity formed by the upper and lower shells.
The assembly mode of combining the upper shell 201 and the lower shell 202 is adopted, so that the round square tube body 300, the light emitting assembly 400, the light receiving assembly 500 and other devices can be conveniently installed in the shells, and the upper shell 201 and the lower shell 202 form an outermost packaging protection shell of the optical module; the upper shell 201 and the lower shell 202 are generally made of metal materials, which is beneficial to realizing electromagnetic shielding and heat dissipation; generally, the housing of the optical module is not made into an integrated component, so that when devices such as a circuit board and the like are assembled, the positioning component, the heat dissipation component and the electromagnetic shielding component cannot be installed, and the production automation is not facilitated.
Typically, the optical module 200 further includes an unlocking component located on an outer wall of the package cavity/lower housing 202 for implementing a fixed connection between the optical module and the upper computer or releasing the fixed connection between the optical module and the upper computer.
The unlocking component is provided with a clamping component matched with the upper computer cage; the end of the unlocking component can be pulled to enable the unlocking component to move relatively on the surface of the outer wall; the optical module is inserted into a cage of the upper computer, and the optical module is fixed in the cage of the upper computer by a clamping component of the unlocking component; by pulling the unlocking component, the clamping component of the unlocking component moves along with the unlocking component, so that the connection relation between the clamping component and the upper computer is changed, the clamping relation between the optical module and the upper computer is released, and the optical module can be drawn out from the cage of the upper computer.
The circuit board 203 is provided with circuit traces, electronic components (such as capacitors, resistors, triodes, and MOS transistors), and chips (such as an MCU, a clock data recovery CDR, a power management chip, and a data processing chip DSP).
The circuit board 203 connects the electrical appliances in the optical module together according to the circuit design through circuit wiring to realize the electrical functions of power supply, electrical signal transmission, grounding and the like.
The circuit board 203 is generally a rigid circuit board, which can also realize a bearing effect due to its relatively hard material, for example, the rigid circuit board can stably bear a chip; when the optical transceiver is positioned on the circuit board, the rigid circuit board can also provide stable bearing; the hard circuit board can also be inserted into an electric connector in the upper computer cage, and specifically, a metal pin/golden finger is formed on the surface of the tail end of one side of the hard circuit board and is used for being connected with the electric connector; these are not easily implemented with flexible circuit boards.
A flexible circuit board is also used in a part of the optical module to supplement a rigid circuit board; the flexible circuit board is generally used in combination with a rigid circuit board, for example, the rigid circuit board may be connected to the optical transceiver device through the flexible circuit board.
The light emitting assembly and the light receiving assembly may be collectively referred to as an optical subassembly. As shown in fig. 4, in the optical module provided in this embodiment, the light emitting module 400 and the light receiving module 500 are both disposed on the circular-square tube 300, the light emitting module 400 is used for generating and outputting signal light, and the light receiving module 500 is used for receiving signal light from outside the optical module. The round and square tube 300 is provided with an optical fiber adapter for connecting an optical module with an external optical fiber, and the round and square tube 300 is usually provided with a lens assembly for changing the propagation direction of the signal light output from the optical transmission assembly 400 or the signal light input from the external optical fiber. The light emitting module 400 and the light receiving module 500 are physically separated from the circuit board 203, and therefore, it is difficult to directly connect the light emitting module 400 and the light receiving module 500 to the circuit board 203, so that the light emitting module 400 and the light receiving module 500 are electrically connected through flexible circuit boards, respectively, in the embodiment of the present application. However, in the embodiment of the present application, the assembling structure of the light emitting module 400 and the light receiving module 500 is not limited to the structure shown in fig. 3 and fig. 4, and other assembling and combining structures may also be used, for example, the light emitting module 400 and the light receiving module 500 are disposed on different tubes, and this embodiment is only exemplified by the structure shown in fig. 3 and fig. 4.
Fig. 5 is an internal structural schematic diagram of an optical module according to an embodiment of the present application. As shown in fig. 5, the optical module 200 provided in the embodiment of the present application includes a circular-square tube 300, a light emitting module 400, and a light receiving module 500. The light emitting assembly 400 is arranged on the round and square tube 300 and is coaxial with the optical fiber adapter of the round and square tube 300, and the light receiving assembly 500 is arranged on the side of the round and square tube 300 and is not coaxial with the optical fiber adapter; however, in the embodiment of the present application, the light receiving assembly 500 may be coaxial with the fiber optic adapter, and the light emitting assembly 400 may be non-coaxial with the fiber optic adapter. The light emitting module 400 and the light receiving module 500 are arranged in the round square tube 300, so that the control of the signal light transmission light path is convenient to realize, the compact design of the interior of the optical module is convenient to realize, and the occupied space of the signal light transmission light path is reduced. In addition, with the development of the wavelength division multiplexing technology, in some optical modules, more than one light emitting module 400 and light receiving module 500 are disposed on the circular square tube 300.
In some embodiments of the present application, a transflective lens is further disposed in the circular-square tube 300, and the transflective lens changes a propagation direction of the signal light to be received by the light receiving module 500 or changes a propagation direction of the signal light generated by the light emitting module 400, so as to facilitate the light receiving module 500 to receive the signal light or output the signal light generated by the light emitting module 400.
Fig. 6 is a structural diagram of an external shape of a light emitting module according to an embodiment of the present disclosure. As shown in fig. 6, the light emitting module 400 provided in this embodiment includes a tube socket 410, a tube cap 420, and other devices disposed in the tube cap 420 and the tube socket 410, wherein the tube cap 420 is covered at one end of the tube socket 410, the tube socket 410 includes a plurality of pins, and the pins are used for electrically connecting the flexible circuit board to other electrical devices in the light emitting module 400, and further electrically connecting the light emitting module 400 to the circuit board 203.
Fig. 7 is a schematic structural view illustrating a tube socket and a tube cap of a light emitting module according to an embodiment of the present disclosure. As shown in fig. 7, the light emitting module 400 includes a laser device 600 therein, and the laser device 600 generates signal light and the generated signal light passes through the cap 420.
Fig. 8 is a schematic structural diagram of a laser device according to an embodiment of the present application. As shown in fig. 8, the laser device 600 includes a laser chip 610 and a ceramic substrate 620, wherein a circuit is laid on the upper surface of the ceramic substrate 620, and the laser chip 610 is connected to the corresponding circuit on the ceramic substrate 620 by wire bonding. Laser chip 610 may be a DFB semiconductor laser chip; the ceramic substrate 620 and the bonding wire between the laser chip 610 and the ceramic substrate 620 are package structures, so that the DFB semiconductor laser chip and the ceramic substrate 620 are packaged to form a DFB laser device. In the embodiment of the present application, the structure of the laser device 600 is not limited to the structure shown in fig. 8, and may be a laser device having another structure.
Fig. 9 is an equivalent structural diagram of a laser device according to an embodiment of the present application. As shown in fig. 9, the package structure is important for high bandwidth and ultra-high bandwidth performance, and has become an important technical barrier affecting high-speed optical communication performance. Any impedance mismatch or resonance effects can severely degrade the performance of the overall product, resulting in a device that cannot be used at high speeds. According TO different module applications and product designs, DFB laser chips may adopt different package structures TO realize high-speed transmission, and the high-speed package forms commonly used in the optical communication industry include coaxial TO, Box package, ceramic package, and the like. In order to verify whether the performance of the package design is good, the package structure with the laser chip needs to be subjected to high-frequency test inspection.
Therefore, before the laser device 600 is assembled to the light emitting module 400 for use, a high-frequency performance test of the laser device 600 is usually performed, and in order to perform the high-frequency performance test of the laser device 600, the embodiment of the present application further provides a laser testing system. The laser testing system provided by the embodiment of the application is used for testing the high-frequency performance of a laser device to be tested (hereinafter, directly referred to as a laser device 600). The high-frequency test items are mainly a bandwidth test (small signal) and an eye pattern test (large signal); the small signal test is to add DC bias current and continuous sine wave modulation signal to the semiconductor laser to test the frequency response characteristic of the laser, and belongs to frequency domain test.
Fig. 10 is a first usage state diagram of a laser test system according to an embodiment of the present application, and fig. 10 shows a basic structure of the laser test system. As shown in fig. 10, a laser test system 700 provided by the embodiment of the present application includes a signal detection device 710, a bias 720, a dc power supply 730, and a matching circuit 740. The signal detection device 710 includes a first signal output terminal, a second signal output terminal, and a signal receiving terminal; the signal detection device 710 is connected with the input end of the biaser 720 through a first signal output end, and the output end of the biaser 720 is connected with the matching circuit 740; the signal detection device 710 is connected to the matching circuit 740 through a second signal output terminal; the output end of the matching circuit 740 is correspondingly connected with the laser device 600; the direct current power supply 730 is connected with the biaser 720 and is used for supplying power to the biaser 720; the signal receiving terminal is connected to the laser device 600 through an optical fiber, and the signal light generated by the laser device 600 is transmitted to the signal receiving terminal through the optical fiber. In the embodiment of the present application, the signal detection device 710, in combination with the biaser 720, implements input of a dc signal and an ac signal to the anode of the laser device 600 and input of an ac signal to the cathode of the laser device 600 to implement input of a differential test signal to the laser device 600 when performing a high-frequency performance test of the laser device 600, and further in some embodiments, the biaser 720 includes a first output terminal and a second output terminal, where the first output terminal is used for transmitting a positive signal and the second output terminal is used for transmitting a negative signal.
In the embodiment of the present application, the signal detection device 710 is used for outputting a test signal to the laser device 600 through a first signal output terminal and a second signal output terminal; the test signal output by the signal detection device 710 through the first signal output end is loaded with a bias signal through the biaser 720, transmitted to the matching circuit 740, and transmitted to the laser device 600 through the matching circuit 740; the signal detection device 710 directly transmits the test signal output by the second signal output end to the matching circuit 740, and transmits the test signal to the laser device 600 through the matching circuit 740; the laser device 600 generates signal light; the signal receiving end of the signal detection device 710 receives the signal light through an optical fiber.
Taking the laser device 600 as a DFB laser device as an example, the internal resistance of the DFB laser chip is usually below 12 ohms, so to meet the transmission performance of high frequency signals, the DFB laser chip is generally designed as a single-ended 25 ohm (differential 50 ohm) package structure for the application of the DFB laser chip in the industry, and the single-ended 25 ohm (differential 50 ohm) package structure is designed at the output end of the laser driving chip, the positive electrode signal and the negative electrode signal of the laser are emitted from the output end of the laser driving chip as differential signals and enter the laser chip through the whole high-speed package structure, and the laser chip emits laser with a modulation signal, that is, the laser chip generates signal light.
The existing high-frequency test system is generally an industry standard using single-ended 50-ohm impedance, and includes that an instrument sends a single-ended 50-ohm high-frequency signal, a coaxial line of a transmission medium uses 50 ohms, a probe for test is also 50 ohms, and the like. Further, the testing of the DFB laser chip which is liable to cause low resistance is not matched with the whole high frequency testing standard, the 25 ohm package structure and the 50 ohm testing environment of the DFB laser chip cause larger electromagnetic wave reflection and high frequency loss, and the performance loss increases with the increase of the testing frequency.
Therefore, in the laser testing system provided by the present application, the matching circuit 740 is disposed between the signal detection device 710, the biaser 720 and the laser device 600, and the matching circuit 740 is configured to match impedances between the package structure of the laser device 600 and the signal transmission networks between the signal detection device 710 and the biaser 720, so as to avoid inaccurate high-frequency performance testing caused by severe impedance adaptation between the package structure of the laser device 600 and the signal transmission networks between the signal detection device 710 and the biaser 720, thereby facilitating to ensure accuracy of the high-frequency performance testing of the laser device to be tested. In some embodiments of the present application, the matching circuit 740 includes a resistor, or a resistor and a capacitor.
Fig. 11 is a schematic structural diagram of a laser device and a matching circuit according to an embodiment of the present disclosure. As shown in fig. 11, the matching circuit 740 includes a first matching sub-circuit 741 and a second matching sub-circuit 742. The input end of the first matching subcircuit 741 is connected with the biaser 720, and the output end of the first matching subcircuit 741 is connected with the anode of the laser device 600; the input terminal of the second matching sub-circuit 742 is connected to the biaser 720, and the output terminal of the second matching sub-circuit 742 is connected to the negative terminal of the laser device 600. As such, the first matching sub-circuit 741 is used for impedance matching between the anode of the laser device 600 and the high-frequency signal transmission line, and the second matching sub-circuit 742 is used for impedance matching between the cathode of the laser device 600 and the high-frequency signal transmission line. The first and second matching sub-circuits 741 and 742 may include resistors, or a combination of resistors and capacitors.
In some embodiments of the present application, the first matching subcircuit 741 includes a first resistor 7411, one end of the first resistor 7411 is connected to the anode of the laser device 600, and the other end of the first resistor 7411 is connected to the output end of the bias device 720, that is, the first resistor 7411 is connected in series between the anode of the laser device 600 and the output end of the bias device 720, so as to implement impedance matching between the anode of the laser device 600 and the high-frequency signal transmission line through the first resistor 7411. Further, the first resistor 7411 is close to the anode of the laser device 600. Optionally, the first resistor 7411 is a chip resistor or a thin film resistor. The resistance of the first resistor 7411 can be selected according to the requirement, and is not particularly limited.
Taking the example that the input terminal of the laser driver chip is designed as a single terminal of 25 ohms, and the single terminal of the high-frequency test system uses 50 ohms impedance, in the embodiment of the present application, the resistance value of the first resistor 7411 is 25 ohms. Impedance matching between the positive electrode package structure of the laser device 600 and the high-frequency signal transmission line is performed through the first resistor 7411, and then the direct current signal and the high-frequency alternating current signal are transmitted to the first resistor 7411 through the high-frequency signal transmission line, and are transmitted to the positive electrode of the laser chip through the positive electrode package structure of the laser device 600 after passing through the first resistor 7411.
In some embodiments of the present application, the second matching sub-circuit 742 includes a second resistor 7421, one end of the second resistor 7421 is connected between the cathode of the laser device 600 and the second signal output terminal of the signal detection device 710, and the other end of the second resistor 7421 is grounded, that is, the second resistor 7421 is connected in parallel between the cathode of the laser device 600 and the second signal output terminal of the signal detection device 710, so as to implement impedance matching between the cathode of the laser device 600 and the high-frequency signal transmission line through the second resistor 7421. Further, the second resistor 7421 is close to the negative electrode of the laser device 600. Optionally, the second resistor 7421 is a chip resistor or a thin film resistor. The resistance of the second resistor 7421 can be selected according to the requirement, and is not particularly limited.
Taking the example that the output end of the laser driving chip is designed to be single-ended 25 ohms, and the single end of the high-frequency testing system uses 50 ohms impedance, in the embodiment of the present application, the resistance value of the second resistor 7421 is 50 ohms. Impedance matching between the cathode packaging structure of the laser device 600 and the high-frequency signal transmission line is performed through the second resistor 7421, so that the high-frequency alternating current signal is transmitted through the high-frequency signal transmission line, one part of the high-frequency alternating current signal is transmitted to a reflux ground through the second resistor 7421, and the other part of the high-frequency alternating current signal is transmitted to the cathode of the laser chip through the cathode packaging structure of the laser device 600.
In the embodiment of the present application, the biaser 720 is connected to the matching circuit 740 through a transmission line, and the test signal applied with the bias signal is transmitted to the matching circuit 740 through the transmission line. Optionally, one end of the transmission line is connected to the biaser 720, and the other end of the transmission line is connected to the matching circuit 740 through a probe.
In the embodiment of the application, the signal detection device comprises a vector network analyzer and an optical wave network analyzer, or the signal detection device comprises a waveform generator and an oscilloscope.
Fig. 12 is a second usage state diagram of a laser testing system according to an embodiment of the present application. As shown in fig. 12, the signal detection apparatus 710 includes a waveform generator 711 and an oscilloscope 712; the first signal output end of the waveform generator 711 is connected to the input end of the biaser 720, the first signal output end of the waveform generator 711 is connected to the matching circuit 740, and the signal receiving end of the oscilloscope 712 is connected to the laser device 600 through an optical fiber. The waveform generator 711 outputs a test signal through the first signal output terminal and the second signal output terminal, and the signal receiving terminal of the oscilloscope 712 receives signal light generated by the laser device 600 according to the test signal through an optical fiber, so as to test the high-frequency performance of the laser device 600.
Finally, it should be noted that: the embodiment is described in a progressive manner, and different parts can be mutually referred; in addition, the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.
Claims (10)
1. A laser testing system is characterized in that the system is used for testing the high-frequency performance of a laser device to be tested and comprises:
the signal detection device comprises a first signal output end, a second signal output end and a signal receiving end, a test signal is transmitted to the laser device to be tested through the first signal output end and the second signal output end, and an optical signal generated by the laser device to be tested is received through the signal receiving end;
the input end of the biaser is connected with the first signal output end, and the output end of the biaser is used for outputting a test signal loaded with a bias signal;
a DC power supply for supplying power to the biaser;
and the input end of the matching circuit is connected with the output end of the biaser and the second signal output end, and the output end of the matching circuit is used for connecting the laser device to be tested.
2. The laser test system of claim 1, wherein the matching circuit comprises:
the input end of the first matching sub-circuit is connected with the biaser, the output end of the first matching sub-circuit is connected with the anode of the laser device to be tested, and the first matching sub-circuit is used for transmitting a positive signal loaded with a bias signal to the laser device to be tested;
and the input end of the second matching sub-circuit is connected with the second signal output end, and the output end of the second matching sub-circuit is connected with the cathode of the laser device to be tested and is used for transmitting a negative signal to the laser device to be tested.
3. The laser test system of claim 2, wherein the first matching sub-circuit comprises a first resistor, one end of the first resistor is connected to the anode of the laser device to be tested, and the other end of the first resistor is connected to the bias device.
4. The laser test system of claim 2, wherein the second matching sub-circuit comprises a second resistor, one end of the second resistor is connected between the negative electrode of the laser device to be tested and the second signal output terminal, and the other end of the second resistor is grounded.
5. The laser test system according to claim 3, wherein when the resistance of the laser device to be tested is 25 ohms and the impedance of the transmission structure between the bias device and the laser device to be tested is 50 ohms, the resistance of the first resistor is 25 ohms, and the first resistor is close to the anode of the laser device to be tested.
6. The laser test system according to claim 4, wherein when the resistance of the laser device to be tested is 25 ohms and the impedance of the transmission structure between the bias device and the laser device to be tested is 50 ohms, the resistance of the second resistor is 50 ohms, and the second resistor is close to the negative electrode of the laser device to be tested.
7. The laser test system according to claim 1, wherein the signal detection device comprises a waveform generator and an oscilloscope, the waveform generator comprises a first signal output end and a second signal output end, and a signal receiving end of the oscilloscope receives the optical signal generated by the laser device to be tested through an optical fiber.
8. The laser test system of claim 3, wherein the first resistor is a chip resistor or a thin film resistor.
9. The laser test system of claim 4, wherein the second resistor is a chip resistor or a thin film resistor.
10. The laser test system of claim 1, further comprising a transmission line, one end of the transmission line being connected to the biaser, the other end of the transmission line being connected to the matching circuit via a probe.
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Application publication date: 20220301 |