CN-116722423-B - Miniature single-frequency Faraday laser with ultra-large tunable range and implementation method thereof

CN116722423BCN 116722423 BCN116722423 BCN 116722423BCN-116722423-B

Abstract

The invention discloses a miniature single-frequency Faraday laser with an oversized tunable range and an implementation method thereof, comprising a laser diode plated with an antireflection film, a collimation module, a miniature Faraday atomic filter, a reflecting cavity mirror with preset reflection ratio, a temperature control module and a temperature control module, wherein the laser diode is used as a seed source of the Faraday laser, the collimation module comprises a collimation lens and a corresponding fixed structure, the miniature Faraday atomic filter filters laser emitted by the laser diode, the laser finally output by the laser is determined by the transmission spectrum of the filter, the reflecting cavity mirror with preset reflection ratio reflects the filtered laser back into a resonant cavity to form oscillation, stable laser is generated, and the rest laser is transmitted out of the laser from the reflecting cavity mirror, and the temperature control module consists of a TEC semiconductor refrigerator and a temperature feedback control circuit and is used for adjusting the working temperature of the laser diode. The volume of the laser designed by the invention is far smaller than that of the main flow Faraday laser, the mechanical stability and the frequency stability of output laser are better, the portability is better, and the laser can play an important role in the fields of laser technology, optical communication, optical network, quantum communication and the like.

Inventors

CHEN JINGBIAO
DANG ANHONG
LIU ZIJIE
SHI TIANTIAN

Assignees

浙江法拉第激光科技有限公司
北京大学

Dates

Publication Date: 20260505
Application Date: 20230616

Claims (5)

1. A miniature single frequency faraday laser of ultra-large tunable range, the laser comprising: A laser diode coated with an antireflection film is used as a seed source of a Faraday laser; the collimation module comprises a collimation lens and a corresponding fixing structure and is used for collimating the laser diode; The micro Faraday atomic filter filters the laser emitted by the laser diode, and the laser finally output by the laser is determined by the transmission spectrum of the filter; a reflecting cavity mirror with preset reflection ratio, which reflects the filtered laser back into the resonant cavity to form oscillation, so as to generate stable laser, and the rest laser is transmitted out of the laser from the reflecting cavity mirror; The temperature control module consists of a TEC semiconductor refrigerator and a temperature feedback circuit and is used for adjusting the working temperature of the laser diode; The integrated mechanical structure of the laser comprises a base, four side plates and a cover plate, wherein the base, the four side plates and the cover plate are used for fixing elements in the laser, and all the elements are assembled into a whole; The micro faraday atomic filter comprises: an alkali metal atom gas cell filled with alkali metal atoms and a buffer gas for transmission spectrum broadening and shaping; The magnetic field generating device is an annular permanent magnet; the other temperature control module is used for monitoring and feedback controlling the temperature of the alkali metal atomic gas chamber; The polarization filtering module is composed of two polarization splitting elements with orthogonal polarization directions and is respectively positioned at two sides of the alkali metal atom air chamber to filter the laser with the polarization directions rotated under the action of a magnetic field; The transmission spectrum bandwidth is 14.64GHz, the cavity length of the Faraday laser is compressed to be 1 cm of the limit, and the free spectrum range of the laser is increased to 14.65 GHz while single-frequency output is realized.
2. The miniature single-frequency Faraday laser with an ultra-large tunable range according to claim 1, wherein piezoelectric ceramics are adhered to the back of the reflecting cavity mirror, and when the laser works, the cavity length of the laser is changed to realize the frequency adjustment of output laser.
3. The ultra-large tunable range miniature single frequency faraday laser of claim 1, wherein the reflective cavity mirror is mounted on a mirror mount, and the position of the mirror mount is changed to adjust the cavity length of the laser.
4. A method of single frequency output of a miniature single frequency faraday laser of ultra-large tunable range, the method being for a miniature single frequency faraday laser of ultra-large tunable range as claimed in any of claims 1-3, the method comprising: A laser diode with a temperature control module and a collimation module is assembled on a laser base, and the position of a lens in the collimation module is adjusted to minimize the divergence angle of laser emitted from the collimation module; The miniature Faraday atomic filter provided with the temperature control module and the magnetic field generating device is assembled on the laser base, the polarization directions of the two polaroids are set to be parallel, and the temperature control module is closed; The mirror base provided with the reflecting cavity mirror and the piezoelectric ceramic is assembled on the laser base, the pitching of the reflecting cavity mirror is changed by adjusting the pitching of the mirror base, so that a laser primary path reflected at the cavity mirror returns, the feedback of the resonant cavity is maximized, and the laser vibrates; rotating the polarizing plate at the position of the atomic filter, which is close to the reflecting cavity mirror, so that the polarizing direction of the polarizing plate is orthogonal to the polarizing direction of the other polarizing plate, and the laser cannot vibrate; Starting a temperature control module of the atomic filter, rotating the polarization direction of laser light near the atomic transition frequency by 90 degrees under the effect of Faraday rotation effect, so that the laser light near the atomic transition frequency is emitted from an orthogonal polaroid, the loss of a resonant cavity is reduced, the laser light restarts, and the frequency of the output laser light is near the atomic transition frequency; the thickness of the piezoelectric ceramic is changed by changing the voltage of the piezoelectric ceramic, so that the cavity length of the laser is changed, and the output frequency of the laser is changed.
5. The method for single frequency output of a miniature single frequency Faraday laser of ultra-large tunable range of claim 4, The tunable laser range is determined by the smaller of the free spectral range of the laser and the transmission spectral bandwidth of the atomic filter; when the working frequency exceeds the transmission spectrum bandwidth of the atomic filter, the loss in the laser cavity is excessive, the laser is closed, and the tunable range is the transmission spectrum bandwidth of the atomic filter; When the operating frequency exceeds one boundary of the free spectral range, the operating frequency jumps to another boundary of the free spectral range.

Description

Miniature single-frequency Faraday laser with ultra-large tunable range and implementation method thereof Technical Field The invention relates to the technical field of semiconductor lasers, in particular to a miniature single-frequency Faraday laser with an ultra-large tunable range and an implementation method thereof. Background Under the action of an external magnetic field, atomic transition spectral line splitting in an alkali metal atomic gas chamber is induced, so that the refractive indexes of left-handed circularly polarized light and right-handed circularly polarized light in incident laser are different after the incident laser passes through the atomic gas chamber. Therefore, after passing through the air chamber, the left circularly polarized light and the right circularly polarized light have a phase difference, and the polarization state of the outgoing laser light rotates, which is the faraday rotation effect. The Faraday anomalous dispersion atomic filter based on the effect has the advantages of narrow bandwidth, high transmissivity and insensitivity to the ambient temperature, and has been widely used for laser frequency selection since the proposal. The external cavity semiconductor laser using Faraday atomic filter as frequency selective device has excellent immunity to the working current and temperature variation of laser diode. For the Faraday laser which is operated normally, the working current and the working temperature of the laser diode are changed greatly, and as long as the working current is kept above the threshold value, the frequency of the output laser does not generate great jitter. The Faraday laser after debugging can still work near the target wavelength after long-time work. Therefore, the Faraday atomic filter is used as an external cavity frequency-selecting device, so that the problems of serious mode jump and remarkable temperature drift of the semiconductor laser diode can be solved, and the high-performance laser with stable output laser frequency, strong anti-interference capability and long-time stable operation can be realized. The method greatly improves the performance of the laser with low cost, develops a new way, and provides a unique solution for the current situation that the semiconductor laser diode with poor performance cannot be used for constructing the high-performance laser. When the Faraday laser made of the pure alkali metal atomic gas chamber works, single-frequency laser output cannot be ensured, and the transmission band width of the pure atomic filter is narrow, so that the Faraday laser made of the pure alkali metal atomic gas chamber has relatively weak anti-interference capability on working current and temperature change of a laser diode. Filling buffer gas into the alkali metal atomic gas chamber can effectively improve the problems, so that the Faraday laser can realize single-frequency output, and the transmission spectrum bandwidth of the atomic filter is widened, so that the anti-interference capability of the Faraday laser is enhanced. The cavity length of the currently mainstream Faraday laser filled with buffer gas is 60cm, on one hand, the corresponding free spectrum range is 250MHz, so that when the laser is swept by changing the cavity length by using piezoelectric ceramics, the sweep frequency range is small, the method cannot be applied to a series of scientific researches and engineering applications with strict requirements on the sweep frequency range, such as detection of the transmission spectrum of a filter, and on the other hand, the large-cavity-length laser also has the problems of large volume, relatively poor portability and mechanical stability, and the like. Disclosure of Invention The invention provides a miniature single-frequency Faraday laser with an ultra-large tunable range and an implementation method thereof, and provides a miniature Faraday atomic filter filled with high-pressure buffer gas, a laser diode with a collimation beam expansion and temperature control module and a reflection cavity mirror with piezoelectric ceramics for realizing the miniature Faraday laser, and a method for stably outputting single-frequency laser and performing large-range laser tuning by using the laser, which are described in detail below: a miniature single frequency faraday laser of ultra-large tuning range, the faraday laser comprising: The laser diode coated with the antireflection film is used as a seed source of the Faraday laser, the emergent wavelength range is large, and the divergence angle of emergent laser is large; The collimation module comprises a collimation lens and a corresponding fixing structure and is used for collimating the laser diode; The miniature Faraday atomic filter filters the laser emitted by the laser diode, and the output laser of the miniature Faraday laser is determined by the transmission spectrum of the miniature Faraday atomic filter; A reflecting cavity mirror with the reflecti