A chip wavelength standard device and a method for manufacturing the same

Abstract

The application discloses a chipped wavelength standard device and a preparation method thereof, and belongs to the field of wavelength standards. The device comprises a frequency discrimination module, a pumping module, a locking module and a substrate. The frequency discrimination module comprises a MEMS atomic gas chamber, a micro-ring resonant cavity and a photodetector; the pumping module mainly comprises a laser and a control circuit thereof; the locking module comprises a phase-locked amplifier, a reference signal source and a PID circuit. The substrate comprises a copper or ceramic heat sink and a TEC temperature controller. The application combines the micro-ring resonant cavity and the MEMS atomic gas chamber, directly pumps the micro-ring resonant cavity integrated optical path by the laser, locks the laser wavelength on the micro-ring resonant cavity resonance peak based on the micro-cavity self-injection locking method, reduces the laser noise and realizes the laser linewidth compression. The micro-cavity evanescent field excites the atomic transition in the atomic gas chamber, and the frequency is discriminated by detecting the fluorescence. The laser frequency is locked by controlling the laser current and the micro-cavity temperature through the frequency discrimination signal, and the chip-level wavelength metrology and value traceability are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to a chip wavelength standard device and a preparation method thereof, and belongs to the field of wavelength standards. BACKGROUND

[0002] Frequency stabilized lasers are widely used in optical measurement, quantum optics, spectral detection, astronomy, optical communication and other fields. Wavelength standards provide value traceability and reference for frequency stabilized lasers, and guarantee the consistency and stability of optical measurement results. Traditional wavelength standard devices are pumped by super-stable lasers, and need to use PDH frequency stabilization and other methods for laser linewidth compression. The wavelength is traced by referring the laser to the atomic transition spectrum, to realize wavelength traceability. The system is complex, the device is bulky, and is easily affected by the environment, which is difficult to use in environments outside the laboratory. Moreover, the super-stable laser is high in cost, and cannot be widely constructed and applied.

[0003] The MEMS atomic cell and the laser chip can be used to realize on-chip laser frequency stabilization, but the wavelength standard device realized by this technical scheme has many problems. First, due to the substrate limitation, the cavity length of the MEMS atomic cell obtained based on the MEMS atomic cell process is generally difficult to exceed 2mm, which makes the optical path of the laser and the atom interaction shorter, and it is difficult to obtain a high signal-to-noise ratio frequency discrimination signal. Compared with the traditional wavelength standard, the long-term frequency stability has not reached the practical level. Secondly, the linewidth of the semiconductor laser chip is wide, and the noise is large. Compared with the super-stable laser source used in the traditional laboratory wavelength standard, the use of semiconductor lasers will result in poor short-term stability of the wavelength standard, and the measurement uncertainty is difficult to meet the needs. SUMMARY

[0004] The purpose of the present application is to provide a chip wavelength standard device and a preparation method thereof, which combines a micro-ring resonant cavity and a MEMS atomic cell. The laser directly pumps the micro-ring resonant cavity integrated optical path, locks the laser wavelength to the micro-ring resonant cavity resonance peak based on the micro-cavity self-injection locking method, reduces the laser noise to realize the linewidth compression of the laser. The atomic transition in the atomic cell is excited by the micro-cavity evanescent field, and the frequency is discriminated by detecting the fluorescence. Then the frequency discrimination signal is used to control the laser current and the micro-cavity temperature to realize the frequency locking of the laser, so as to provide a chip-level frequency stabilized laser for optical measurement, quantum optics and other applications, and realize chip-level wavelength measurement and value traceability.

[0005] The purpose of the present application is realized by the following technical scheme:

[0006] The chip wavelength standard device comprises a frequency discrimination module, a pumping module, a locking module and a substrate.

[0007] The micro-ring resonator chip comprises an Add-Drop type waveguide-micro-ring resonator coupling light path, a Y-type coupler, a mode spot converter and a micro-ring resonator heater.

[0008] The frequency discrimination module surrounds the MEMS atomic cell, the micro-ring resonator chip is integrated on one inner wall of the MEMS atomic cell, and the photodetector chip is integrated on the other outer wall of the MEMS atomic cell; the pumping laser is frequency discriminated and wavelength-locked based on the two-photon transition principle; the pumping light is incident from the mode spot converter waveguide end face exposed by the micro-ring resonator chip on the side of the MEMS atomic cell, is injected into the Add-drop type micro-ring resonator through the on-chip waveguide Y-type coupler, excites the alkali metal atoms in the MEMS atomic cell through the evanescent field of the micro-ring resonator, realizes the two-photon transition, the integrated photodetector on the other side of the MEMS atomic cell detects the alkali metal atom fluorescence as the frequency discrimination signal, and the wavelength locking of the pumping laser is realized through the locking circuit chip; the MEMS atomic cell and the Add-drop type micro-ring resonator are combined together, the pumping laser resonates in the micro-ring resonator, the high on-chip light power density characteristics of the micro-ring resonator itself are utilized to enhance the interaction between the pumping light and the alkali metal atoms in the cell, the two-photon transition is more easily excited on the chip, the frequency discrimination characteristics of the laser are utilized by using the two-photon transition effect, the wavelength of the laser is locked to the two-photon transition spectrum line of the alkali metal atom energy level, and thus the chip wavelength standard is realized.

[0009] The micro-ring resonator chip is an Add-drop type micro-ring resonator integrated light path processed on an SOI substrate, an SiNOI substrate, an LNOI substrate or a glass substrate.

[0010] The chip wavelength standard device disclosed by the application, wherein a through hole is formed on a silicon substrate by using a deep silicon etching method in a MEMS atomic cell of a frequency discrimination module, a micro ring resonant cavity chip is bonded to the silicon substrate by using a bonding method, and a micro ring resonant cavity pattern part is aligned with the through hole; after filling with an alkali metal element, the other side of the through hole is closed by using a transparent substrate through the bonding method; and a photoelectric detector chip on the other side is fixed in an area aligned with the through hole by using a bonding method, a pre-preparation method or a gluing method. The edge of the micro ring resonant cavity chip contains a waveguide end surface of a mode spot converter for coupling of pump light. Pump light is incident from the side of the frequency discrimination module, passes through the waveguide end surface of the mode spot converter on the micro ring resonant cavity chip, enters an Add-Drop cavity after passing through a Y-shaped coupler, and interacts with atoms in the MEMS atomic cell through the evanescent field of the micro ring resonant cavity. The pump module and the frequency discrimination module are directly attached to a substrate, the frequency discrimination module is integrally temperature-controlled through the substrate, and the heater on the micro ring resonant cavity chip is adjusted through a circuit to adjust the resonant peak of the micro ring resonant cavity on the atomic transition line. The pump module and the frequency discrimination module are directly coupled without an isolator in between, and the wavelength of the pump laser is locked on the microcavity resonant peak by using the self-injection locking effect; the pump light is referenced to the atoms by aligning the microcavity resonant peak with the atomic transition spectrum line through thermal tuning, so that the wavelength standard is realized. The pump module contains an edge-emitting laser chip, and contains a current driver and a temperature controller circuit of the laser.

[0011] The application discloses a preparation method of a chip wavelength standard device.

[0012] Step one, prepare a double-side polished silicon substrate, realize a through hole on the silicon substrate by using a photoetching etching process, and define the position of a MEMS atomic cell.

[0013] Step two, prepare a single-side polished silicon substrate, grow a lower silicon oxide layer by using thermal oxidation, grow a silicon nitride core layer by using LPCVD, realize the patterning of the silicon nitride layer by using a photoetching etching process, complete the pattern layer of the micro ring resonant cavity chip, grow an upper silicon oxide layer by using PECVD, and perform high-temperature annealing. The position of the micro ring resonant cavity needs to be aligned with the position of the through hole on the silicon substrate in step one.

[0014] Step three, planarize the upper silicon oxide layer of the wafer in step two by using a CMP method, then remove the upper silicon oxide layer directly above the micro ring resonant cavity by using a photoetching etching process, and bond the wafer to one side of the silicon substrate in step one by using an anodic bonding process, so that the position of the micro ring resonant cavity is aligned with the position of the through hole.

[0015] Step four, prepare a double-sided polished transparent substrate, including but not limited to glass, quartz, lithium niobate, sapphire, etc., directly prepare a photodetector on the substrate, or use bonding, adhesive to fix the commercial photodetector chip. The photodetector position is aligned with the through-silicon via position on the silicon substrate in step one.

[0016] Step five, fill the wafer in step three with an alkali metal releasing agent.

[0017] Step six, use an anodic bonding process to bond the wafer in step four with the wafer in step five.

[0018] Step seven, after releasing the alkali metal atoms, the preparation of the frequency discriminator module is completed.

[0019] Step eight, prepare the substrate, pump module, and locking module, mount the TEC, thermistor and its control circuit on the substrate, mount the pump module and frequency discriminator module on the substrate, and the pump module needs to be aligned with the side waveguide end face of the frequency discriminator module. Stack the locking module above the pump module, and connect the pump module current source modulation interface with the corresponding interface of the locking module. The locking module and the frequency discriminator module are connected by wire bonding, thus forming a wavelength standard chip and completing the preparation of the chipized wavelength standard.

[0020] Advantages:

[0021] 1. The chipized wavelength standard device and its preparation method disclosed by the application use an edge-emitting laser chip to directly pump a microcavity chip, based on the method of microcavity self-injection locking, lock the laser wavelength to the micro-ring resonant cavity resonance peak, reduce the laser noise to narrow the laser line width, solve the problem of wide semiconductor laser chip line width and large noise, and improve the wavelength stability of the pump light source.

[0022] 2. The chipized wavelength standard device and its preparation method disclosed by the application combine the micro-ring resonant cavity chip with the MEMS atomic cell through micro-nano processing method, realize the integration of the frequency discriminator module, and improve the problem of low integration and large volume of the traditional wavelength standard optical path physical system.

[0023] 3, The application discloses a chipped wavelength standard device and a preparation method thereof. A micro-ring resonant cavity in an add-drop configuration is injected through an on-chip waveguide Y-coupler. The evanescent field of the micro-ring resonant cavity excites alkali metal atoms in a MEMS atomic cell, and two-photon transition is realized. An integrated photodetector on the other side of the MEMS atomic cell detects the alkali metal atom fluorescence as a frequency discrimination signal. The wavelength locking of a pump laser is realized through a locking circuit chip. The resonant light prolongs the optical path of the pump laser and the alkali metal atom interaction, and solves the problem that the laser and atom interaction time is limited under the micron / sub-micron size of the MEMS atomic cell. The two-photon transition effect is enhanced by using the high on-chip light power of the micro-ring resonant cavity, the signal-to-noise ratio of the frequency discrimination signal is significantly improved, and the frequency stability of the final output wavelength is improved. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 (a) is a top view of a chipped wavelength standard device system, and (b) is a stacked cross-sectional view of each module.

[0025] Figure 2 It is a schematic diagram for coupling the pump module and the frequency discrimination module.

[0026] Figure 3 It is a top view of a MEMS atomic cell.

[0027] 1- frequency discrimination module, 2- pump module, 3- locking module, 4- substrate, 5- output collimated light path.

[0028] 1.1- micro-ring resonant cavity chip, 1.2- MEMS atomic cell, 1.3- photodetector chip.

[0029] 1.1.1- micro-ring resonant cavity, 1.1.2- Y-coupler, 1.1.3- mode spot converter waveguide end face.

[0030] 1.2.1- through silicon via, 1.2.2- silicon substrate. DETAILED DESCRIPTION

[0031] In order to better illustrate the purpose and advantages of the application, the content of the application is further described below in combination with the drawings and examples.

[0032] Example 1:

[0033] As Figure 1 (a), Figure 1 (b), Figure 2As shown, this embodiment discloses a chip-based wavelength standard device, comprising a frequency discrimination module 1, a pump module 2, a locking module 3, and a substrate 4, as well as a necessary output collimating optical path 5; wherein the frequency discrimination module 1 includes a micro-ring resonator chip 1.1, a MEMS atomic gas cell 1.2, and a photodetector 1.3. The pump module 2 mainly includes a laser and its control circuit, and the locking module 3 includes an MCU controller, a lock-in amplifier, a reference signal source, and a PID circuit; the substrate 4 includes a copper or ceramic heat sink and a TEC temperature controller; the frequency discrimination module 1 is used to extract the error signal of the pump laser wavelength drift, realize the correction of the pump laser wavelength drift, and thus lock the laser wavelength to the atomic energy level transition. The MEMS atomic gas cell 1.2 is as follows. Figure 3 As shown.

[0034] The microring resonator chip 1.1 uses a silicon substrate, a microring resonator 1.1.1 composed of silicon oxide upper and lower cladding layers and a silicon nitride core layer, an Add-Drop type waveguide-microring resonator coupling optical path, a Y-type coupler 1.1.2, a mode spot converter waveguide end face 1.1.3, and an aluminum electrode forming a microring resonator heater.

[0035] Frequency discrimination module 1 is surrounded and filled with 87 A MEMS atomic cell 1.2 containing Rb atoms has a microring resonator chip 1.1 integrated on one inner wall and a 420nm photomultiplier tube integrated on the other outer wall as a photodetector chip 1.3. Frequency discrimination and wavelength locking of the pump laser are performed based on the two-photon transition principle. A 778nm wavelength side-emitting laser pump light is incident from the inverted conical mode converter waveguide end face 1.1.3 exposed on the side of the microring resonator chip 1.1 on the MEMS atomic cell 1.2, and injected into the add-drop configuration microring resonator 1.1.1 through an on-chip waveguide Y-coupler 1.1.2. The evanescent field of the microring resonator excites the contents of the MEMS atomic cell 1.2. 87 Rb atoms enable two-photon transitions; a photodetector on the other side of the MEMS atomic gas chamber 1.2 and a chip detector 1.3 are used for detection. 87 Rb atomic fluorescence serves as the frequency discrimination signal, and the wavelength of the pump laser is locked through the locking module 3. By combining the MEMS atomic gas cell 1.2 with the add-drop configuration micro-ring resonator 1.1.1, the pump laser resonates within the micro-ring resonator 1.1.1. Utilizing the high on-chip optical power density of the micro-ring resonator 1.1.1 itself, the interaction between the pump light and the alkali metal atoms in the gas cell is enhanced, making it easier to excite two-photon transitions on-chip. By utilizing the frequency discrimination characteristics of the laser through the two-photon transition effect, the laser wavelength is locked to the two-photon transition spectrum of the alkali metal atomic energy level, thereby realizing chip-based wavelength standardization.

[0036] Micro-ring resonator chip 1.1, using 500 μm thick silicon substrate, silicon oxide under cladding 6 μm, silicon oxide on cladding 4 μm, and silicon nitride core layer 300 nm, to achieve Add-drop type micro-ring resonator integrated optical path.

[0037] Chip wavelength standard device, in the MEMS atomic cell 1.2 of the frequency discrimination module 1, using deep silicon etching method to form a silicon through hole 1.2.1 on a 500 μm thick silicon substrate 1.2.2, using anodic bonding method to bond the micro-ring resonator chip 1.1 with the silicon substrate 1.2.2, and the micro-ring resonator 1.1.1 pattern part is aligned with the silicon through hole 1.2.1; fill 87 After Rb, using a double-throw glass substrate, the other side of the silicon through hole 1.2.1 is closed by bonding method; the other side uses a 420 nm photomultiplier tube chip as a photodetector 1.3 chip, which is fixed on the glass and silicon through hole 1.2.1 aligned area by bonding method. The edge of the micro-ring resonator chip 1.1 contains the waveguide end face 1.1.3 of the mode spot converter for coupling of pump light. Pump light is incident from the side of the frequency discrimination module 1, passes through the waveguide end face 1.1.3 of the mode spot converter on the micro-ring resonator chip 1.1, and enters the Add-Drop cavity after passing through the Y-type coupler 1.1.2. The evanescent field of the micro-ring resonator 1.1.1 interacts with the atoms in the MEMS atomic cell 1.2. The pump module 2 and the frequency discrimination module 1 are directly attached to the substrate 4, and the frequency discrimination module 1 is controlled by the substrate 4 as a whole, and the heater on the micro-ring resonator chip 1.1 is adjusted by the circuit to adjust the peak of the micro-ring resonator on the atomic transition line, about 778.1 nm. The pump module 2 and the frequency discrimination module 1 are directly coupled without isolator in between, and the self-injection locking effect is used to lock the pump laser wavelength on the microcavity resonance peak; after thermal tuning, the microcavity resonance peak is aligned with the atomic transition spectrum, which can reference the pump light to the atom, thereby realizing the wavelength standard. The pump module 2 contains a pump laser chip which is an edge-emitting laser chip, and contains a current driver and temperature controller circuit of the laser.

[0038] The preparation method of the chip wavelength standard device disclosed in the embodiment is as follows:

[0039] Step one, prepare a double-side polished silicon substrate 1.2.2 with a thickness of 500 μm, use photolithography etching process to realize silicon through hole 1.2.1 on silicon substrate 1.2.2, and define the position of MEMS atomic cell 1.2.

[0040] Step two, prepare a single-side polished silicon substrate with a thickness of 500 μm, a lower cladding layer of thermal oxidation silicon with a thickness of 6 μm, a core layer of silicon nitride with a thickness of 300 nm, and a patterned silicon nitride layer by a lithography and etching process to form a micro-ring resonator chip 1.1.1. Grow an upper cladding layer of thermal oxidation silicon with a thickness of 4 μm by PECVD and perform high-temperature annealing at 1100°C. The position coordinates of the micro-ring resonator 1.1.1 need to be consistent with the position coordinates of the silicon via 1.2.1 in step (1).

[0041] Step three, planarize the upper cladding layer of thermal oxidation silicon of the wafer in step two by a CMP method, then remove the upper cladding layer of thermal oxidation silicon directly above the micro-ring resonator 1.1.1 by a lithography and etching process to expose the core layer of silicon nitride. Bond the wafer to one side of the silicon substrate 1.2.2 in step one by an anodic bonding process, and the position of the micro-ring resonator 1.1.1 is aligned with the position of the silicon via 1.2.1.

[0042] Step four, prepare a double-side polished glass substrate, and fix a commercial photomultiplier tube with a wavelength of 420 nm as a photodetector 1.3 chip by an anodic bonding method. The position of the photodetector is aligned with the position of the silicon via 1.2.1 in step one.

[0043] Step five, fill the wafer in step three with an alkali metal releasing agent.

[0044] Step six, bond the wafer in step four to the wafer in step five by an anodic bonding process.

[0045] Step seven, release 87 After the Rb atom is released, the preparation of the frequency discriminator module 1 is completed.

[0046] Step eight, prepare a substrate 4, a pump module 2, and a locking module 3, mount a TEC, a thermistor, and their control circuit on the substrate, mount the pump module 2 and the frequency discriminator module 1 on the substrate, and the pump module 2 needs to be aligned with the side waveguide end face of the frequency discriminator module 1. Stack the locking module 3 above the pump module 2, and connect the current source modulation interface of the pump module 2 to the corresponding interface of the locking module 3. Connect the locking module 3 to the frequency discriminator module 1 by wire bonding. Thus, a wavelength standard chip is formed, and the preparation of the chip-based wavelength standard is completed.

[0047] The above detailed description further describes the purpose, technical solutions, and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and does not limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A chip-scale wavelength standard device, characterized by, The chip wavelength standard device comprises a frequency discrimination module, a pumping module, a locking module and a base; wherein the frequency discrimination module comprises a MEMS atomic cell, a micro-ring resonant cavity and a photodetector; the pumping module mainly comprises a laser and a control circuit thereof; the locking module comprises an MCU controller, a phase-locked amplifier, a reference signal source and a PID circuit; and the base comprises a copper or ceramic heat sink and a TEC temperature controller; the frequency discrimination module is used for extracting an error signal of wavelength drift of the pumping laser, correcting the wavelength drift of the pumping laser, and thus locking the wavelength of the laser to an atomic energy level transition; The micro-ring resonant cavity chip comprises an Add-Drop type waveguide-micro-ring resonant cavity coupling optical path, a Y-type coupler, a mode spot converter and a micro-ring resonant cavity heater. The frequency discrimination module surrounds the MEMS atomic cell, the micro-ring resonant cavity chip is integrated on an inner wall of one side of the MEMS atomic cell, and a photodetector chip is integrated on an outer wall of the other side of the MEMS atomic cell; the pumping laser is frequency discriminated and wavelength-locked based on a two-photon transition principle; the pumping light is incident from a mode spot converter waveguide end face exposed by the micro-ring resonant cavity chip on the side of the MEMS atomic cell, is injected into the Add-Drop type micro-ring resonant cavity through the on-chip waveguide Y-type coupler, excites alkali metal atoms in the MEMS atomic cell through the evanescent field of the micro-ring resonant cavity, and realizes two-photon transition; the integrated photodetector on the other side of the MEMS atomic cell detects alkali metal atom fluorescence as a frequency discrimination signal, and wavelength locking of the pumping laser is realized through a locking circuit chip; the MEMS atomic cell and the Add-Drop type micro-ring resonant cavity are combined together, the pumping laser resonates in the micro-ring resonant cavity, the high on-chip optical power density characteristic of the micro-ring resonant cavity is utilized to enhance the interaction between the pumping light and the alkali metal atoms in the cell, the two-photon transition is more easily excited on the chip, the frequency discrimination characteristic of the laser is utilized through the two-photon transition effect, the wavelength of the laser is locked to the two-photon transition spectral line of the alkali metal atomic energy level, and thus the chip wavelength standard is realized.

2. The chip-scale wavelength standard device of claim 1, wherein, The micro-ring resonant cavity chip is an Add-Drop type micro-ring resonant cavity integrated optical path processed on an SOI substrate, a SiNOI substrate, an LNOI substrate or a glass substrate.

3. The chip wavelength standard device of claim 1, wherein the frequency discrimination module is characterized in that, in the MEMS atomic cell, a through silicon via is formed on a silicon substrate by deep silicon etching, a micro-ring resonant cavity chip is bonded to the silicon substrate by bonding, and a pattern part of the micro-ring resonant cavity is aligned with the through silicon via; after filling with an alkali metal element, the other side of the through silicon via is closed by bonding with a transparent substrate; and a photodetector chip on the other side is fixed in an area aligned with the through silicon via by bonding, a pre-preparation method or an adhesive method.

4. The chip-scale wavelength standard device of claim 1, wherein, The edge of the micro-ring resonant cavity chip comprises a waveguide end face of a mode spot converter, which is used for coupling of the pumping light.

5. The chip-scale wavelength standard device of claim 1, wherein, The pumping light is incident from the side of the frequency discrimination module, enters the Add-Drop cavity through the waveguide end face of the mode spot converter on the micro-ring resonant cavity chip, and interacts with the atoms in the MEMS atomic cell through the evanescent field of the micro-ring resonant cavity after passing through the Y-type coupler.

6. The chip-scale wavelength standard device of claim 1, wherein, The pump module and the frequency discrimination module are directly attached to the substrate, the frequency discrimination module is integrally temperature-controlled by the substrate, and the heater on the micro-ring resonant cavity chip is adjusted by the circuit to adjust the resonant peak of the micro-ring resonant cavity on the atomic transition line.

7. The chip-scale wavelength standard device of claim 1, wherein, The pump module and the frequency discrimination module are directly coupled without an isolator in between, the wavelength of the pump laser is locked on the micro-cavity resonant peak by using the self-injection locking effect, the pump light is referenced to the atom by aligning the micro-cavity resonant peak with the atomic transition spectrum line through thermal tuning, so as to realize the wavelength standard.

8. The chip-scale wavelength standard device of claim 1, wherein, The pump module comprises a pump laser chip which is an edge-emitting laser chip, and a current driver and a temperature controller circuit of the laser.

9. A method for manufacturing a chip-scale wavelength standard device, for manufacturing a chip-scale wavelength standard device according to any one of claims 1 to 8, characterized in that, The method comprises the following steps: Step one, prepare a double-side polished silicon substrate, use a photolithography etching process to realize a through hole on the silicon substrate to define the position of the MEMS atomic chamber; Step two, prepare a single-side polished silicon substrate, use thermal oxidation to grow a silicon oxide lower cladding layer, use LPCVD to grow a silicon nitride core layer, realize the patterning of the silicon nitride layer by a photolithography etching process, complete the pattern layer of the micro-ring resonant cavity chip, use PECVD to grow a silicon oxide upper cladding layer and perform high-temperature annealing, and the position of the micro-ring resonant cavity needs to be aligned with the position of the through hole on the silicon substrate in step one; Step three, use the CMP method to planarize the silicon oxide upper cladding layer of the wafer in step two, then use a photolithography etching process to remove the silicon oxide upper cladding layer directly above the micro-ring resonant cavity, and use an anodic bonding process to bond the wafer with one side of the silicon substrate in step one, so that the position of the micro-ring resonant cavity is aligned with the position of the silicon through hole; Step four, prepare a double-side polished transparent substrate, directly prepare a photodetector on the substrate, or fix a photodetector chip by using bonding or gluing, and the position of the photodetector is aligned with the position of the silicon through hole on the silicon substrate in step one; Step five, fill the wafer in step three with an alkali metal releasing agent; Step six, use an anodic bonding process to bond the wafer in step four with the wafer in step five; Step seven, after releasing the alkali metal atoms, the preparation of the frequency discrimination module is completed; Step eight, prepare a substrate, a pump module and a locking module, attach a TEC, a thermistor and a control circuit thereon, attach the pump module and the frequency discrimination module on the substrate, the pump module needs to be aligned with the side waveguide end face of the frequency discrimination module, stack the locking module above the pump module, connect the current source modulation interface of the pump module with the corresponding interface of the locking module, and connect the locking module with the frequency discrimination module by wire bonding, so as to form a wavelength standard chip and complete the preparation of the chip-based wavelength standard.

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