A wavelength positioning system for a faraday laser

Abstract

The application discloses a wavelength positioning system of a Faraday laser, and belongs to the technical field of optical measurement, which comprises a Faraday laser, laser output by the Faraday laser passes through a 1 / 2 optical fiber coupler, laser output from the 1 / 2 optical fiber coupler is input into a polarization maintaining fiber, the polarization maintaining fiber is coupled with a whispering gallery mode micro-ring core cavity, a laser output end of the polarization maintaining fiber is connected with a photoelectric detector, and an oscilloscope is connected to the photoelectric detector; the central wavelength of the Faraday laser is adjusted, and the wavelength of the Faraday laser is scanned in the process until a Lorentz transmission spectrum generated after laser is coupled with the micro-ring core cavity is obtained on the oscilloscope. The wavelength positioning system utilizes the whispering gallery mode micro-ring core cavity to replace a commercial wavelength meter, and realizes rapid wavelength positioning of the Faraday laser. Compared with a traditional commercial wavelength meter, the whispering gallery mode micro-ring core cavity has a lower manufacturing cost.

Description

Technical Field

[0001] This invention relates to the field of optical metrology, and more particularly to a wavelength positioning system for a Faraday laser. Background Technology

[0002] Frequency standards are essential for radio, microwave, and timing systems, and have wide applications in navigation, communication, remote sensing, and basic science. Optical frequencies are typically three orders of magnitude higher than microwave frequencies, thus offering better frequency stability. A good optical frequency standard requires an ultra-stable laser as the light source. The laser wavelength is locked onto the ultra-stable cavity using the PDH frequency-locking method to achieve good short-term frequency stability, and then locked onto an atomic transition line to obtain even better long-term stability.

[0003] Faraday lasers incorporate atomic filters, exhibiting frequency selectivity based on the polarization direction of the transmitted light, enabling them to output narrow-linewidth laser light corresponding to the transition frequencies of atomic spectral lines. They also possess excellent shock resistance and temperature fluctuation resistance.

[0004] However, Faraday lasers typically have multiple operating wavelengths, with each wavelength differing by more than 1 GHz. A wavelength meter is required to find the desired operating wavelength. Wavelength meters are usually expensive, bulky, and difficult to integrate with the optical path.

[0005] Therefore, a method is proposed to replace the wavelength meter with the frequency selectivity of the whispering-gallery mode optical microcavity, thus realizing a miniaturized and low-cost wavelength positioning system.

[0006] It should be noted that the above content falls within the inventor's technical knowledge and does not necessarily constitute prior art. Summary of the Invention

[0007] To address the aforementioned problems, the purpose of this invention is to provide a wavelength positioning system for Faraday lasers. This system utilizes a whispering-gallery mode optical microcavity to replace commercial wavelength meters, overcoming the bottlenecks of bulky and expensive wavelength meters. It improves the system's portability and ease of handling, reducing its cost. Furthermore, it enhances operational convenience, allowing users to quickly achieve wavelength positioning without complex setup and calibration processes. This wavelength positioning device will provide crucial technical support for the commercialization of Faraday lasers. Its portability, ease of handling, and low cost enable Faraday lasers to be more widely applied in various scenarios, such as portable medical devices and on-site testing instruments, demonstrating broad market prospects and application value.

[0008] To achieve the above objectives, this invention proposes a wavelength positioning method for a Faraday laser. The wavelength positioning system includes a Faraday laser, the laser output from the Faraday laser passes through a 1-to-2 fiber coupler, one of the output lasers from the 1-to-2 fiber coupler is sent to a tapered fiber, the tapered fiber is coupled to a whispering-gallery mode micro-ring cavity, the laser output end of the tapered fiber is connected to a photodetector, and an oscilloscope is connected to the photodetector.

[0009] By adjusting the center wavelength of the Faraday laser, the Lorentz-type transmission spectrum generated after the laser couples with the micro-ring cavity is obtained on an oscilloscope, thus completing the wavelength positioning of the Faraday laser.

[0010] Preferably, the whispering-gallery mode microring cavity is a SiO2 microring cavity.

[0011] Preferably, the SiO2 microring cavity parameters are as follows:

[0012] Diameter 45-55 micrometers, quality factor between 5×10 5 -10 6 The free spectral range is 1.33 THz.

[0013] Preferably, the diameter of the tapered optical fiber is 0.8-1.2 micrometers and the total length is 0.9-1.1 meters.

[0014] Preferably, the encapsulation method for the whispering-gallery mode microring cavity is as follows:

[0015] First, the micro-ring cavity is coupled to the tapered optical fiber. Then, the optical fiber and the micro-cavity are cured and encapsulated using UV-curing adhesive, and placed in a PDMS container.

[0016] Preferably, the microring cavity employs high-precision temperature control measures.

[0017] Preferably, the temperature control measures specifically include:

[0018] A thermoelectric cooler is connected to a TEC temperature control device, and a PID control circuit is used to finely adjust the temperature of the thermoelectric cooler to achieve a temperature stability of 0.0018°C / 24 hours. The encapsulated microring cavity is then placed on the thermoelectric cooler, achieving a wavelength stability of 1.9 × 10⁻⁶. -5 The resonant wavelength of the microring cavity is changed by altering its temperature over 24 hours, so that the resonant wavelength is within the expected operating wavelength of the Faraday laser.

[0019] The wavelength positioning system for a Faraday laser proposed in this invention can bring the following beneficial effects:

[0020] 1. The wavelength positioning system of this invention utilizes a whispering-gallery mode microring cavity instead of a commercial wavelength meter to achieve rapid wavelength positioning of Faraday lasers, representing a technological innovation. Compared to traditional commercial wavelength meters, the whispering-gallery mode microring cavity may have lower manufacturing costs, thereby helping to reduce the overall cost of the Faraday laser wavelength positioning system.

[0021] 2. The micro-ring cavity in the wavelength positioning system of this invention is extremely small, typically only tens of micrometers in diameter, making it highly suitable for integration into miniaturized optical systems. This enhances the portability and maneuverability of Faraday laser systems. These two advantages contribute to the further commercialization and productization of Faraday laser systems. Attached Figure Description

[0022] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0023] Figure 1 This is a schematic diagram illustrating the principle of Faraday laser wavelength positioning.

[0024] Figure 2 This is a schematic diagram of the microring cavity fabrication process.

[0025] Figure 3 This is a schematic diagram of a micro-ring core cavity coupled with a tapered optical fiber and placed in a PDMS container. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the measurement method involved in this invention clearer, the following description and explanation will be based on the method of this invention and in conjunction with specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0027] A wavelength positioning system for a Faraday laser, wherein the resonant cavity used in the system is a whispering-gallery mode microring core cavity, such as... Figure 1 As shown, the wavelength positioning system includes a Faraday laser. The laser output from the Faraday laser passes through a 1-to-2 fiber coupler. One of the output lasers from the 1-to-2 fiber coupler is sent to a tapered fiber. The tapered fiber interacts with the micro-ring cavity inside the PDMS container, coupling it with the whispering-gallery mode micro-ring cavity. The laser output end of the tapered fiber is connected to a photodetector, and an oscilloscope is connected to the photodetector.

[0028] Adjust the center wavelength of the Faraday laser and scan the wavelength of the Faraday laser in the process until the Lorentz-type transmission spectrum generated after the laser couples with the micro-ring cavity is obtained on the oscilloscope, thus completing the positioning of the Faraday laser wavelength.

[0029] The fabrication method of the microring cavity is as follows:

[0030] The pattern on the photomask is transferred onto the photoresist using photolithography, such as... Figure 2 As shown, the SiO2 film is wet-etched using HF buffer solution to transfer the photoresist pattern onto the SiO2 film. The Si is then etched using XeF2 gas to form a structure in which Si pillars support the SiO2 disk. The SiO2 disk is then reflowed using a CO2 laser to form a SiO2 microring cavity.

[0031] SiO2 microring cavity parameters: diameter 50 micrometers, quality factor between 5×10⁻⁶. 5 -10 6 The free spectral range is 1.33 THz.

[0032] The fabrication method of tapered optical fiber is as follows:

[0033] The middle part of a 125-micrometer diameter optical fiber is placed above a hydrogen flame, and both ends of the fiber are pulled by a stepper motor to make the fiber thinner in the middle and thicker at both ends, forming a tapered fiber. The thinnest part in the middle of the tapered fiber has a diameter of 1 micrometer, and the total length is 1 meter.

[0034] The packaging method for the whispering-gallery mode microring cavity is as follows:

[0035] First, the micro-ring core cavity is coupled with the tapered optical fiber. The optical fiber and the micro-cavity are then cured and encapsulated using UV-curing adhesive and placed in a PDMS container with a volume of 1cm × 0.5cm × 0.5cm.

[0036] Specifically: such as Figure 3 As shown, the thinnest part of the tapered fiber (1 micrometer in diameter) is coupled to a whispering-gallery mode microring cavity, and the bottom of the microring cavity is adhered to the bottom of a PDMS (polydimethylsiloxane) groove. Two small holes are made on both sides of the PDMS groove to allow the fiber to pass through. Finally, the top of the PDMS groove is sealed with a PDMS thin plate, forming a structure as shown. Figure 2 The structure shown illustrates that the PDMS container serves to protect the microring cavity from contamination.

[0037] The micro-ring cavity employs high-precision temperature control measures, as detailed below:

[0038] A thermoelectric cooling chip is connected to a TEC temperature control device (thermoelectric cooling temperature controller). A PID control circuit (an electronic circuit that adjusts system errors based on a combination of proportional (P), integral (I), and derivative (D) control methods to achieve precise automatic control) is used to finely regulate the temperature of the thermoelectric cooling chip. This ensures that the resonant wavelength of the micro-ring cavity matches the operating wavelength of the Faraday laser, achieving a temperature stability of 0.002°C / 24 hours. Placing the encapsulated micro-ring cavity on the thermoelectric cooling chip further enhances its wavelength stability to 1.9 × 10⁻⁶. -5 The resonant wavelength of the microring cavity is guaranteed to remain within a wide range by changing the temperature of the microring cavity over 24 hours.

[0039] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A wavelength positioning system for a Faraday laser, the wavelength positioning system comprising a Faraday laser, characterized in that, The laser output from the Faraday laser passes through a 1-to-2 fiber coupler. One of the output lasers from the 1-to-2 fiber coupler is sent to a tapered fiber. The tapered fiber is coupled to the whispering-gallery mode micro-ring cavity. The laser output end of the tapered fiber is connected to a photodetector, and an oscilloscope is connected to the photodetector. By adjusting the center wavelength of the Faraday laser, the Lorentz-type transmission spectrum generated after the laser couples with the micro-ring cavity is obtained on an oscilloscope, thus completing the wavelength positioning of the Faraday laser.

2. The wavelength positioning system for a Faraday laser according to claim 1, characterized in that, The whispering-gallery mode microring cavity is a SiO2 microring cavity.

3. The wavelength positioning system for a Faraday laser according to claim 2, characterized in that, The SiO2 microring core cavity parameters are as follows: Diameter 45-55 micrometers, quality factor between 5×10⁵-10⁶, free spectral range 1.33 THz.

4. The wavelength positioning system for a Faraday laser according to claim 3, characterized in that, The tapered optical fiber has a diameter of 0.8-1.2 micrometers and a total length of 0.9-1.1 meters.

5. The wavelength positioning system for a Faraday laser according to claim 4, characterized in that, The encapsulation method for the whispering-gallery mode microring cavity is as follows: First, the micro-ring cavity is coupled to the tapered optical fiber. Then, the optical fiber and the micro-cavity are cured and encapsulated using UV-curing adhesive, and placed in a PDMS container.

6. The wavelength positioning system for a Faraday laser according to claim 5, characterized in that, The micro-ring cavity employs high-precision temperature control measures.

7. The wavelength positioning system for a Faraday laser according to claim 6, characterized in that, The temperature control measures are specifically as follows: A thermoelectric cooler is connected to a TEC temperature control device, and a PID control circuit is used to finely adjust the temperature of the thermoelectric cooler, achieving a temperature stability of 0.0018°C / 24 hours. A packaged micro-ring cavity is placed on the thermoelectric cooler, achieving a wavelength stability of 1.9 × 10⁻⁵ nm / 24 hours. The resonant wavelength is changed by altering the temperature of the micro-ring cavity. This ensures that its resonant wavelength is within the expected operating wavelength of the Faraday laser.

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