CN-115566520-B - Self-mode-selection self-injection feedback single-frequency laser

CN115566520BCN 115566520 BCN115566520 BCN 115566520BCN-115566520-B

Abstract

The invention discloses a self-mode-selection self-injection feedback single-frequency laser which comprises a pumping source, a coupling system, an input coupling mirror, a laser crystal, an output coupling mirror, a total reflection cavity mirror group, a reflection type temperature body holographic Bragg grating and a semiconductor refrigerating device. The composite cavity oscillator is formed by the inner cavity ring oscillator and the outer cavity reflection type temperature body holographic Bragg grating, the reflection type temperature body holographic Bragg grating performs mode self-selection on incident laser with constant resonance diffraction efficiency, and then the incident laser is injected into the ring oscillator with constant laser intensity, so that stable unidirectional operation of the composite cavity ring oscillator is realized, and the problem of structural instability of the composite cavity laser is solved. Greatly prolongs the service life of the oscillation photons in the cavity, and ensures that the output laser has the characteristics of high efficiency, low noise and narrow linewidth.

Inventors

GUO YONGRUI
ZHANG NANA
TAN MINGSEN
MA YONG
PAN WU

Assignees

重庆邮电大学

Dates

Publication Date: 20260512
Application Date: 20221027

Claims (9)

1. A self-mode-selectable self-injection feedback single frequency laser, comprising: The device comprises a pumping source (1), a coupling system (2), an input coupling mirror (3), a laser crystal (7), an output coupling mirror (4), a total reflection cavity mirror group, a reflection type temperature body holographic Bragg grating (8) and a semiconductor refrigerating device (9); the reflection type temperature volume holographic Bragg grating (8) is arranged behind the output coupling mirror (4) and is positioned at the same horizontal plane with the output coupling mirror (4); the total reflection cavity lens group, the input coupling lens (3), the output coupling lens (4) and the laser crystal (7) form a closed ring oscillator together; The ring oscillator and the reflection type temperature volume holographic Bragg grating (8) form a compound cavity ring oscillator together; The laser emitted by the pumping source (1) is injected into the inner cavity of the ring oscillator through the coupling system (2), and the laser in the horizontal output direction of the ring oscillator is injected into the inner cavity of the ring oscillator in a reflection mode through the reflection type temperature volume holographic Bragg grating (8) after mode selection is carried out by constant resonance diffraction efficiency; The temperature of the reflection type temperature volume holographic Bragg grating (8) is regulated and controlled by a semiconductor refrigeration device (9); effective gain bandwidth spectral bandwidth of compound cavity ring oscillator The selection range of (2) is 6GHz less than or equal to ≤ , wherein, Gain bandwidth for the laser crystal; spectral bandwidth of the reflection type temperature volume holographic Bragg grating (8) The selection range of (2) is 6GHz less than or equal to ≤ Effective narrowing of the emission spectrum width of a laser Wherein The total intracavity loss for the compound cavity ring oscillator.
2. The self-mode-selected self-injection feedback single frequency laser of claim 1, wherein the composite cavity length of the composite cavity ring oscillator Double the inner cavity length of the ring oscillator And twice the external cavity length of the reflection type temperature volume holographic Bragg grating (8) And (3) summing.
3. The self-mode-selection self-injection feedback single-frequency laser according to claim 1, wherein the amplification factor of the coupling system (2) depends on the laser beam waist radius at the laser crystal (7), and the ratio of the laser beam waist radius at the pump source (1) to the laser beam waist radius at the laser crystal (7) is 1.2.
4. The self-mode-selection self-injection feedback single-frequency laser according to claim 1, wherein the angle between the reflection type temperature volume holographic Bragg grating (8) and the incident laser depends on the laser intensity required by unidirectional stable operation of the laser, and the diffraction efficiency of the reflection type temperature volume holographic Bragg grating (8) on the vertically incident laser is 95%.
5. The self-mode-selection self-injection feedback single-frequency laser device according to claim 1, wherein the reflection type temperature volume holographic Bragg grating (8) is made of silicate glass crystals, the front end face of the reflection type temperature volume holographic Bragg grating (8) is plated with an oscillation laser high-transmittance film, and the rear end face of the reflection type temperature volume holographic Bragg grating is plated with an oscillation laser high-reflectance film.
6. A self-mode-selected self-injection feedback single frequency laser as claimed in claim 1, wherein the laser crystal (7) is any one of visible light, near infrared, mid-infrared laser crystal.
7. The self-mode selected self-injection fed back single frequency laser of claim 1, wherein said total reflection cavity mirror assembly comprises at least one plano-concave lens.
8. A self-mode-selected self-injection feedback single frequency laser as claimed in claim 1, wherein the temperature control accuracy of the semiconductor refrigeration device (9) is 0.005 ℃.
9. The self-mode-selected self-injection feedback single frequency laser of claim 1, wherein the tuning frequency of the laser is , wherein, Is the laser resonance wavelength at the normal temperature of 25 ℃, Is the coefficient of thermal expansion of the grating, Is the thermo-optic coefficient of the grating, Is the absolute value of the difference between the actual temperature of the grating and 25 ℃ at normal temperature.

Description

Self-mode-selection self-injection feedback single-frequency laser Technical Field The invention relates to the technical field of lasers and lasers, in particular to a self-mode-selection self-injection feedback single-frequency laser. Background The single-frequency laser with high power, tunable, low noise and narrow linewidth has important and wide application in the basic scientific research fields of quantum information, cold atom physics, precise spectrum, precise measurement and the like, the deep space detection fields of space laser communication, satellite navigation and the like, and the national defense safety fields of space laser radar, laser remote sensing and the like. At present, one main preparation mode of the high-power single-frequency laser is to adopt a ring laser resonant cavity, adopt the ring resonant cavity to eliminate the space hole burning effect of laser, insert a Faraday optical isolator in the ring laser resonant cavity to force the laser to operate unidirectionally, combine with mode selection elements such as etalons or nonlinear elements to realize single-frequency operation of the laser, and finally realize stable unidirectional and single-frequency operation of the ring laser resonant cavity. The mode selection element such as an etalon or a nonlinear element introduced into the cavity of the single-frequency laser can introduce loss to influence the output power of the laser, and the damage threshold of the etalon of the mode selection element is a factor for limiting the output power of the laser and is also one of unstable factors for the laser. At higher power in the cavity of the laser, the thermal lens effect of the magneto-optical rotation medium composing the laser isolator is not negligible, which affects the stable operation characteristics of the laser, and the isolator device is one of the factors causing the complicated structure and unstable system of the laser. In addition, the mode of realizing the high-power single-frequency laser is that the laser propagating in the forward direction or the reverse direction is reflected and injected into the annular laser resonant cavity again by using a high-reflection lens outside the annular laser resonant cavity, the laser is forced to run unidirectionally by forming laser intensity difference by two laser beams propagating in the reverse direction, meanwhile, the single-frequency operation of the laser is realized by combining an intra-cavity mode selection element (such as an etalon), the unidirectional operation of the laser is finally realized, the unidirectional operation of the laser is controlled by the laser intensity injected by the feedback of an outer cavity, the single longitudinal mode operation of the laser is mainly controlled by the mode selection effect of the mode selection element of the inner cavity, and intense mode competition always exists between the oscillation mode of the outer cavity and the oscillation laser of the inner cavity, which is a main factor for causing the mode instability of the composite cavity laser. Also, the introduction of mode select elements in the ring resonator increases the device instability of the laser. In order to form stable laser intensity difference between two counter-propagating lasers, a half-wave plate, a prism and a quarter-wave plate combination are required to be introduced on a reflection injection laser light path, the quarter-wave plate and the prism combination are used for adjusting the reflection laser to reach constant intensity, the half-wave plate is used for calibrating the polarization direction of the counter-injection laser, however, the introduction of the quarter-wave plate, the prism and the half-wave plate increases the complexity and the instability of the laser, which is a main factor causing the structural instability of the compound cavity laser. Disclosure of Invention The invention aims to provide a self-mode-selection self-injection feedback single-frequency laser, which forms a composite cavity oscillator together by an inner cavity ring oscillator and an outer cavity reflection type temperature body holographic Bragg grating, and the reflection type temperature body holographic Bragg grating performs mode self-selection on incident laser with constant resonance diffraction efficiency and then injects the laser into the ring oscillator with constant laser intensity, so that stable unidirectional operation of the composite cavity ring oscillator is realized, and the problem of structural instability of the composite cavity laser is solved. The invention is realized by the following technical scheme: a self-mode-selecting self-injection feedback single-frequency laser comprises The device comprises a pumping source, a coupling system, an input coupling mirror, a laser crystal, an output coupling mirror, a total reflection cavity mirror group, a reflection type temperature body holographic Bragg grating and a semiconductor refri