阅读说明：本技术 覆盖全部增益谱线的连续可调谐钛宝石激光器及其方法 (Continuously tunable titanium gem laser covering all gain spectral lines and method thereof ) 是由 卢华东 曹雪辰 苏静 彭堃墀 于 2020-04-24 设计创作，主要内容包括：本发明涉及一种覆盖全部增益谱线的连续可调谐钛宝石激光器及其方法,该连续可调谐钛宝石激光器包括泵浦源、望远镜系统、光学谐振腔、钛宝石晶体和双折射滤波片。由泵浦源出射的激光光束经望远镜系统聚焦后作用于光学谐振腔内的钛宝石晶体上,经钛宝石的受激辐射过程产生荧光,通过光学谐振腔的选模和放大过程产生激光,在光学谐振腔内震荡后经第二平面镜透射形成激光输出；同时,通过电机控制器驱动电机驱动旋转台调整双折射滤波片光轴在通光面投影与激光入射面的夹角,从起始角度18.4°扫描至36.2°,以获得覆盖全部增益谱线的输出激光。通过本发明,能够在不改变干涉级的情况下可实现均匀连续的700至1000nm波长调谐,同时不会影响激光器的运行稳定性。(The invention relates to a continuously tunable titanium sapphire laser covering all gain spectral lines and a method thereof. Laser beams emitted by the pumping source are focused by the telescope system and then act on the titanium sapphire crystal in the optical resonant cavity, fluorescence is generated through the stimulated radiation process of the titanium sapphire, laser is generated through the mode selection and amplification processes of the optical resonant cavity, and the laser is transmitted through the second plane mirror after being oscillated in the optical resonant cavity to form laser output; meanwhile, a motor controller drives a motor to drive a rotating table to adjust the included angle between the projection of the optical axis of the birefringent filter on the light-passing surface and the laser incidence surface, and the included angle is scanned from 18.4 degrees to 36.2 degrees from the initial angle so as to obtain output laser covering all gain spectral lines. By the invention, uniform and continuous 700-1000 nm wavelength tuning can be realized without changing the interference level, and the operation stability of the laser is not influenced.)

1. A continuously tunable titanium sapphire laser capable of covering all gain spectral lines is characterized by comprising a pumping source (1), a telescope system (2), an optical resonant cavity (3), a titanium sapphire crystal (4) and a birefringence filter (5); pumping light output by the pumping source (1) is emitted into a first plano-concave mirror (9) of the optical resonant cavity (3) through the telescope system (2); the optical resonant cavity (3) is a four-mirror 8-shaped annular resonant cavity structure and comprises a first plano-concave mirror (9), a second plano-concave mirror (10), a first plane mirror (11) and a second plane mirror (12), a birefringent filter (5) is arranged on a light path between the first plano-concave mirror (9) and the second plane mirror (12) at a Brinell angle, and a titanium sapphire crystal (4) is arranged on the light path between the first plano-concave mirror (9) and the second plano-concave mirror (10); the double refraction filter plate (5) is formed by bonding quartz crystals with the thicknesses of 0.5mm, 1.0mm, 2.5mm and 4.5mm with gasket optical cement, light passing surfaces of the crystals are parallel to each other, the directions of the optical axes are parallel to each other, and an included angle between the directions of the optical axes and the light passing surfaces is 29.4 degrees; the birefringence filter (5) is connected with a motor drive rotating platform (6), and the motor drive rotating platform (6) is controlled by a motor controller (7); an optical one-way device (13) is arranged on an output optical path of the second plane mirror (12).

2. A continuously tunable titanium sapphire laser covering the entire gain line according to claim 1, characterised in that the thickness of the spacer optical glue bonded between crystals in the birefringent filter (5) is set at 2 mm.

3. The continuously tunable Titania laser according to claim 1, wherein the output wavelength of the pump source (1) is 400-600nm, the polarization direction is horizontal polarization, and the pumping mode is end-pumped.

4. Continuously tunable titanium sapphire laser covering the whole gain line according to claim 1, characterized by the fact that the optical isolator (13) is made up of magnetically and naturally optically active crystals with an applied magnetic field or is an extra-cavity reflector made up of a third flat mirror (8) placed vertically in the reverse optical path after the second flat mirror (12).

5. The continuously tunable titanium sapphire laser device as claimed in claim 1, wherein the concave surface of the first plano-concave mirror (9), the concave surface of the second plano-concave mirror (10), and the reflective surface of the first plano-mirror (11) are coated with high reflective film with wavelength band of 680-1030nm, and the reflective surface of the second plano-mirror (12) is coated with dielectric film with 5% transmittance for wavelength band of 680-1030 nm.

6. A method of line gain using a continuously tunable titanium-sapphire laser as claimed in any one of claims 1 to 5, by a continuously tunable titanium-sapphire laser covering the entire gain line, comprising:

laser beams emitted by the pumping source (1) are focused by the telescope system (2) and then act on the titanium gem crystal (4) in the optical resonant cavity (3) to generate fluorescence through the stimulated radiation process of the titanium gem, laser is generated through the processes of mode selection and amplification of the optical resonant cavity (3), a reverse light path passes through a light path formed by the first plano-concave mirror (9), the birefringent filter (5), the second plano-concave mirror (12), the first plano-concave mirror (11), the second plano-concave mirror (10), the titanium sapphire crystal (4) and the first plano-concave mirror (9), the introduction of the optical one-way device (13) is lost, and finally an oscillation light path formed by the second plano-concave mirror (10), the first plano-concave mirror (11), the second plano-concave mirror (12), the birefringent filter (5), the first plano-concave mirror (9), the titanium sapphire crystal (4) and the second plano-concave mirror (10) is transmitted through the second plano-concave mirror (12);

when laser oscillates in the optical resonant cavity (3), a motor is driven by a motor controller (7) to drive a rotating table (6), and the included angle between the projection of the optical axis of the birefringent filter (5) on a light passing surface and the laser entrance surface is adjusted to 18.4 degrees;

and a motor is driven by a motor controller (7) to drive a rotating table (6), and the included angle between the projection of the optical axis of the scanning birefringence filter (5) on the light transmission surface and the laser entrance surface is scanned from 18.4 degrees to 36.2 degrees from the initial angle so as to obtain output laser covering all gain spectral lines.

Technical Field

The invention relates to the technical field of lasers, in particular to a continuously tunable titanium sapphire laser covering all gain spectral lines and a method for covering all gain spectral lines.

Background

The titanium gem crystal has a wide fluorescence spectrum range (700 nm-1000 nm) and can cover absorption peaks of alkali metal atoms such as potassium, rubidium and cesium, so that the all-solid-state continuously tunable laser taking the titanium gem as the gain medium can be applied to research on quantum science aspects such as atom capture and cooling, spectral analysis, precision measurement and quantum calculation. In addition, the blue-violet light obtained by utilizing the frequency doubling technology can be applied to scientific researches in aspects of optical clocks, optical storage, medicine and the like; the output wavelength is expanded to 1550nm by using an optical parameter down-conversion technology, and the wavelength is just in a third low-loss transmission window of the single-mode optical fiber, so that the optical fiber can be applied to the research of quantum secret communication.

In order to make the output wavelength of the laser continuously tunable, it is necessary to insert a suitable tuning element within the cavity. The birefringent filter is often used as a coarse tuning element of a laser because of its advantages of small insertion loss, convenient tuning, etc. In 2010, the photoelectric research institute of Shanxi university utilized a birefringent filter with a thickness ratio of 1:2:4, and experimentally achieved a wide tuning of 100 nm by determining the intra-cavity loss and the optimal transmittance of the output mirror.

At present, four commercial continuously tunable titanium gem lasers are available for scientific research, namely MBR series from the company of Coherent, Matisse 2 series from the company of Spectra-physics, SolsTis series from the company of M square in England, and TiS-SF series from the company of Tekhnoscan, Russia. In the tuning process of the above lasers, the cavity mirror of the resonant cavity needs to be adjusted or the operation mode of the laser needs to be changed, which undoubtedly increases the complexity and instability of the laser and can affect the output beam of the laser.

Disclosure of Invention

The aim is to widen the tuning range of the existing continuously tunable titanium sapphire laser, and to cover all gain spectral lines under the condition of only rotating the birefringent filter plate without changing any element and operation mode in the cavity.

The technical scheme adopted by the invention for solving the technical problems is as follows: constructing a continuously tunable titanium-sapphire laser covering the entire gain line, comprising:

the device comprises a pumping source, a telescope system, an optical resonant cavity, a titanium sapphire crystal and a birefringence filter; pumping light output by a pumping source is emitted into a first plano-concave mirror of the optical resonant cavity through a telescope system; the optical resonant cavity is a four-mirror 8-shaped annular resonant cavity structure and comprises a first plano-concave mirror, a second plano-concave mirror, a first plane mirror and a second plane mirror, a birefringent filter is arranged on a light path between the first plano-concave mirror and the second plane mirror at a Brinell angle, and a titanium sapphire crystal is arranged on the light path between the first plano-concave mirror and the second plano-concave mirror; the double refraction filter plate is formed by bonding quartz crystals with the thicknesses of 0.5mm, 1.0mm, 2.5mm and 4.5mm with gasket optical cement, light passing surfaces of the crystals are parallel to each other, the directions of the optical axes are parallel to each other, and an included angle between the direction of the optical axis and the light passing surfaces is 29.4 degrees; the birefringence filter is connected with a motor drive rotating platform, and the motor drive rotating platform is controlled by a motor controller; an optical one-way device is arranged on an output light path of the second plane mirror.

Wherein, the thickness of the gasket optical cement adhered between the crystals in the birefringent filter is set to be 2 mm.

Wherein, the output wavelength of the pumping source is 400-600nm, the polarization direction is horizontal polarization, and the pumping mode is end-face pumping.

The optical one-way device is an optical one-way device formed by a magneto-optical rotation crystal and a natural rotation crystal of an external magnetic field, or an extra-cavity reflecting device formed by a third flat mirror vertically arranged in a reverse light path behind the second flat mirror.

Wherein, the concave surface of the first plano-concave mirror, the concave surface of the second plano-concave mirror and the reflecting surface of the first plano-concave mirror are plated with high-reflection films with the wave band of 680 and 1030nm, and the reflecting surface of the second plano-concave mirror is plated with a dielectric film with 5% of transmissivity to the wave band of 680 and 1030 nm.

The technical scheme adopted by the invention for solving the technical problems is as follows: a method of constructing a continuously tunable titanium-sapphire laser covering all gain lines, comprising:

laser beams emitted by a pumping source are focused by a telescope system and then act on a titanium gem crystal in an optical resonant cavity, fluorescence is generated through the stimulated radiation process of the titanium gem, laser is generated through the mode selection and amplification process of the optical resonant cavity, a reverse light path passes through a light path formed by a first planoconvex lens, a birefringence filter, a second planoconvex lens, a first planoconvex lens, a second planoconvex lens, a titanium gem crystal and the first planoconvex lens, the introduction of an optical one-way device is lost, and finally an oscillation light path formed by the second planoconvex lens, the first planoconvex lens, the second planoconvex lens, the birefringence filter, the first planoconvex lens, the titanium gem crystal and the second planoconvex lens is transmitted through;

when the laser oscillates in the optical resonant cavity, the motor is driven by the motor controller to drive the rotating table, and the included angle between the projection of the optical axis of the birefringent filter on the light passing surface and the laser entrance surface is adjusted to 18.4 degrees;

and driving a motor to drive a rotating table by using a motor controller, and scanning an included angle between the projection of an optical axis of the scanning birefringence filter on a light-passing surface and a laser incidence surface from an initial angle of 18.4 degrees to 36.2 degrees to obtain output laser covering all gain spectral lines.

Compared with the prior art, the invention has the advantages that:

1) the continuous tunable titanium gem laser capable of covering all gain spectral lines has a simple structure; through the birefringent filter, the wavelength tuning of 700-1000 nm can be realized uniformly and continuously under the condition of not changing the interference level;

2) the method for continuously tuning the titanium sapphire laser capable of covering all gain spectral lines realizes continuous tuning of wavelength on the basis of only controlling the motor controller, and the operation stability of the laser cannot be influenced in the process.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

fig. 1 is a schematic structural diagram of a continuously tunable titanium sapphire laser covering all gain lines according to the present invention.

Fig. 2 is a schematic structural diagram of a birefringent filter of a continuously tunable titanium sapphire laser covering all gain spectral lines according to the present invention.

Fig. 3 is a schematic diagram showing the tuning experimental results of a continuously tunable titanium sapphire laser covering all gain lines according to the present invention.

Detailed Description

For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

Referring to fig. 1, the present invention provides a continuously tunable titanium sapphire laser covering the entire gain line, comprising:

the device comprises a pumping source 1, a telescope system 2, an optical resonant cavity 3, a titanium sapphire crystal 4 and a birefringence filter 5; pumping light output by the pumping source 1 is incident into a first plano-concave mirror 9 of the optical resonant cavity 3 through the telescope system 2; the optical resonant cavity 3 is a four-mirror 8-shaped annular resonant cavity structure and comprises a first plano-concave mirror 9, a second plano-concave mirror 10, a first plane mirror 11 and a second plane mirror 12, a birefringent filter 5 is arranged on a light path between the first plano-concave mirror 9 and the second plane mirror 12 at a Brinell angle, and a titanium sapphire crystal 4 is arranged on the light path between the first plano-concave mirror 9 and the second plano-concave mirror 10; the birefringent filter 5 is formed by bonding quartz crystals with the thicknesses of 0.5mm, 1.0mm, 2.5mm and 4.5mm with gasket optical cement, light passing surfaces of the crystals are parallel to each other, the directions of the optical axes are parallel to each other, and an included angle between the direction of the optical axis and the light passing surfaces is 29.4 degrees; the birefringent filter 5 is connected with a motor driving rotating platform 6, and the motor driving rotating platform 6 is controlled by a motor controller 7; an optical one-way device 13 is arranged on the output light path of the second plane mirror 12.

In the four-mirror 8-shaped annular resonant cavity structure, four mirrors are arranged in an upper row and a lower row, a first plano-concave mirror 9 and a second plano-concave mirror 10 are arranged in the upper row, a first plano-concave mirror 11 and a second plano-concave mirror 12 are arranged in the lower row, and concave surfaces of the first plano-concave mirror 9 and the second plano-concave mirror 10 are opposite; the four mirrors are arranged at angles which not only ensure that the resonant cavity is in closed resonance, but also compensate well for astigmatism introduced by the titanium sapphire crystal 4 due to the Brinell angle placement.

Wherein, the thickness of the gasket optical cement adhered between the crystals in the birefringent filter 5 is set to be 2 mm.

Wherein, the output wavelength of the pump source 1 is 400-600nm, the polarization direction is horizontal polarization, and the pumping mode is end-face pumping.

The optical isolator 13 is an optical isolator composed of a magneto-optical crystal and a natural optical crystal of an external magnetic field, or an extra-cavity reflecting device composed of a third flat mirror 8 vertically arranged in a reverse optical path behind the second flat mirror 12.

Wherein, the concave surface of the first plano-concave mirror 9, the concave surface of the second plano-concave mirror 10, and the reflective surface of the first plano-mirror 11 are coated with a high reflective film with a wavelength band of 680 and 1030nm, and the reflective surface of the second plano-mirror 12 is coated with a dielectric film with 5% transmittance to the wavelength band of 680 and 1030 nm.

The output light beam of the pumping source 1 enters the optical resonant cavity 3 through the coupling of the telescope system 2, acts on the titanium sapphire crystal 4, and in order to obtain high pumping efficiency, 532nm laser with the polarization mode of horizontal polarization is selected, the laser passes through the stimulated radiation of the titanium sapphire crystal 4 and the mode selection and amplification process of the optical resonant cavity 3, and the laser of the light path formed by the first concave mirror 9, the birefringent filter 5, the second concave mirror 12, the first plane mirror 11, the second concave mirror 10, the titanium sapphire crystal 4 and the first concave mirror 9 in the reverse light path is reinjected by the third plane mirror 8, and finally stable output laser is obtained.

The birefringent filter 5 shown in fig. 2 is formed by four quartz crystals and crescent-shaped gasket optical cement, the optical axes and the light transmission surfaces of the four crystals are 29.4 degrees, the thicknesses of the quartz crystals are 0.5mm, 1.0mm, 2.5mm and 4.5mm respectively, the light transmission surfaces of the crystals are parallel to each other, the optical axes of the four crystals are parallel to each other, and the included angle between the optical axis direction and the light transmission surfaces is 29.4 degrees.

The invention provides a method for covering all gain spectral lines by a continuously tunable titanium sapphire laser, which comprises the following steps:

laser beams emitted by a pumping source 1 are focused by a telescope system 2 and then act on a titanium sapphire crystal 4 in an optical resonant cavity 3, fluorescence is generated through the stimulated radiation process of the titanium sapphire, laser is generated through the mode selection and amplification process of the optical resonant cavity 3, a reverse light path passes through a light path formed by a first planoconvex mirror 9, a birefringent filter 5, a second planoconvex mirror 12, a first planoconvex mirror 11, a second planoconvex mirror 10, the titanium sapphire crystal 4 and the first planoconvex mirror 9, an optical one-way device 13 is lost, and finally an oscillation light path formed by the second planoconvex mirror 10, the first planoconvex mirror 11, the second planoconvex mirror 12, the birefringent filter 5, the first planoconvex mirror 9, the titanium sapphire crystal 4 and the second planoconvex mirror 10 is transmitted through the second planoco;

when the laser oscillates in the optical resonant cavity 3, the motor is driven by the motor controller 7 to drive the rotating table 6, and the included angle between the projection of the optical axis of the birefringent filter 5 on the light passing surface and the laser surface is adjusted to 18.4 degrees;

and a motor is driven by a motor controller 7 to drive a rotating platform 6, and the included angle between the projection of the optical axis of the scanning birefringence filter 5 on the light transmission surface and the laser incidence surface is scanned from 18.4 degrees to 36.2 degrees from the initial angle so as to obtain output laser covering all gain spectral lines.

The birefringent filter 5 is placed between the second plane mirror 12 and the first planoconvex mirror 9 of the optical resonator 3 at a Brinell angle, and the included angle between the projection of the optical axis of the birefringent filter 5 on the light-passing surface and the laser surface is adjusted to 18.4 degrees. And a motor controller 7 is used for driving a motor to drive a rotating table 6, and the included angle between the projection of the optical axis of the scanning birefringence filter 5 on the light-passing surface and the laser entrance surface is scanned from 18.4 degrees to 36.2 degrees of the initial angle to finally obtain the output laser continuously tuned from 700nm to 1000 nm. As shown in fig. 3, the output wavelength is in the range of 705nm to 935nm, the pump power is 12W higher than 1.5W, and the beam has better optical characteristics.

While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.