CN1300927A

CN1300927A - Optical fibre coil type laser refrigerator

Info

Publication number: CN1300927A
Application number: CN 99126983
Authority: CN
Inventors: 秦伟平
Original assignee: Changchun Institute of Optics Fine Mechanics and Physics of CAS
Current assignee: Changchun Institute of Optics Fine Mechanics and Physics of CAS
Priority date: 1999-12-23
Filing date: 1999-12-23
Publication date: 2001-06-27
Anticipated expiration: 2019-12-23
Also published as: CN1105894C

Abstract

An optical fibre oil type laser refrigerating unit based on the inverse Stokes fluorescent refrigerating principle is composed of cold core, optical fibre wound on cold core, pump laser, laser transverse mode perturbator, beam incidence lens set, beam exit lens set and reflector. Said optical fibre has inner core made of fluorescent refrigerating material and jacket allowing the inverse Stokes fluorescence to pass through it and having partial trap to pump laser. Its advantages are high regrigerating effect and short light path.

Description

Optical fibre coil type laser refrigerator

The invention belongs to the laser cooling technical field, is a kind of fluorescence refrigerator that adopts method that optical fiber twines cold core to carry out laser cooling.

Anti-stokes fluorescent cooling (Anti-Stokes Fluorescent Cooling) is also referred to as laser cooling (Laser Cooling).Since nineteen ninety-five, this technology has obtained development at full speed.At present, people utilize the method for laser cooling to obtain the temperature also lower than domestic refrigerator refrigerating chamber.Because this technology has full photosensitiveness, refrigerator based on it has advantages such as volume is little, in light weight, electromagnetic-radiation-free, friction, noiseless, therefore also just had very tempting application prospect and met the specific (special) requirements in fields such as military affairs, space, integrated optics, microelectronics, medical science, and paid attention to by the foreign study person.As a basic fundamental, the breakthrough of laser cooling technology will inevitably cause many temperature being had the high-tech practicability of specific (special) requirements, promotes those fields and advances.

The shape of laser cooling medium has fundamental influence to refrigerating efficiency, because pump beam all has certain geometry when introducing, how to bring into play the maximum utility of pump beam, is a key of refrigerator design.The breadboard technical staff of U.S. Los Alamos has just obtained lower cryogenic temperature after adopting sample fiber.In addition, the shape of refrigerant all plays a part crucial to the absorption of pump light and the ejaculation of anti-Stokes fluorescence.Principle is exactly to make the light path of advancing of pump beam long as much as possible, and the light path of advancing of anti-Stokes fluorescence is short as much as possible.When we used laser pump (ing), the directionality of pump light and collimation were that we carry out refrigerator when design utilizable two big advantages.When carrying out the design of refrigeration device, good directionality and collimation help the realization that pump light office falls into (trapping).Therefore, also just can obtain the another one inference, refrigerant is the smaller the better to the pumping scattering of light.Anti-Stokes fluorescence is fully to the same sex, does not possess special directionality, and such feature also will give sufficient consideration when carrying out the design of fluorescence refrigerator.Therefore, these characteristics of synthetic pumping laser and anti-Stokes fluorescence, we can obtain such conclusion: elongated shape of medium helps the fluorescence refrigeration most.After laser was imported from an end, pump light can be along the bigger light path of axially advancing of refrigerant, and small distance just penetrates outside the medium and the fluorescence that sends can be advanced very.

The purpose of this invention is to provide a kind of pump beam optical length of advancing, the short optical fibre coil type laser refrigerator of the capable light path of anti-Stokes fluorescence.

Optical fiber is typical slender type optical element, and it has the constraint effect to the propagation of light.The optical cable that uses in optical-fibre communications at present can be with the hundreds of rice of lightray propagation.Such optical path length is far longer than 25 meters contemplated light path of Los Alamos researchers.

The present invention makes the rare earth ion of fluorescence refrigerating material absorb laser, and launches anti-Stokes fluorescence with the fluorescence refrigerating material in the laser pump (ing) optical fiber.Owing to launch anti-Stokes fluorescence, the molecule in the fiber optic materials (ion) releases energy with the form of light, reduces energy state, and then temperature descends.

Accompanying drawing is the coil form refrigeration device principle structure based on optical fiber, and it is made up of cold core, optics such as optical fiber, pump laser, light beam incident set of lenses, light beam exit lens group, speculum on the cold core.Employed optical fiber should have optical fiber inner core and surrounding layer structure.Fiber cores adopts the fluorescence refrigerating material; Surrounding layer allows anti-Stokes fluorescence to see through and pumping laser is had office to fall into effect.Cold core does not absorb for anti-Stokes fluorescence, has good thermal conductivity simultaneously.

The present invention is described in further detail below in conjunction with drawings and Examples.

Fig. 1 is a schematic diagram of the present invention, and Fig. 2 is by being used the optical fiber schematic diagram.Among the figure, the 1-pump laser; Select diode laser or ti sapphire laser in the present embodiment for use, the wavelength that is sent is: 1015 nanometers; The 2-wavelength is the pumping laser bundle of 1015 nanometers; 3-laser transverse mode disarrangement device its role is to the transverse mode upset with the pumping laser of incident, to increase the absorption of refrigeration optical fiber to laser; The collimation converging optical lens group of 4-incident pumping laser; 5,6,7-laser cooling optical fiber, specifically describe as Fig. 2; The 8-cold core, its feature is: not absorptive pumping laser and laser cooling optical fiber institute emitted fluorescence, simultaneously, it also possesses good heat-conducting.Select the material of sodium chloride crystal in the present embodiment for use as cold core.Being shaped as of cold core is cylindrical, is processed with the helical flute that the external diameter with laser cooling optical fiber 5,6,7 is complementary on its surface, and purpose is to increase refrigeration optical fiber and contacts with the surface of cold core, improves the heat transmission between them; 9-is from the pumping laser of refrigeration optical fiber 7 outgoing; The optical lens group that 10-assembles shoot laser 9; Shoot laser reflected back refrigeration optical fiber 7 after the speculum of 11-high reflectance, its effect are to gather; The 12-fiber cores, the material that present embodiment adopts is ZBLANP:Yb ³⁺Glass; The 13-optical fiber jacket adopts fluorescence is not absorbed the material that simultaneously pumping laser is had high reflectance.

The concrete work of present embodiment is as follows: the 1015 nanometer pumping lasers 2 that sent by laser instrument 1 at first pass through transverse mode disarrangement device 3, make pumping laser have chaotic transverse mode.4 pairs of such laser beams of optical lens group focus on and make in the light beam incident system cold light fibre 5.The Yb of refrigeration fiber cores 12 ³⁺Ion absorbs the laser of 1015 nano wave lengths and launches anti-Stokes fluorescence, thereby the temperature of optical fiber 5,6,7 and cold core 8 is reduced.Cold core 8 is that abutment surface contacts transmission with heat between the optical fiber 5,6,7.Do not have absorbed pumping laser to penetrate from optical fiber 7 after converged on the speculum 11 by optical lens group 10,10 gatherings enter optical fiber 7 to emitted laser through optical lens group once more.So the purpose of design is to improve the utilization rate of pumping laser, increases the absorption of optical fiber to pumping laser.Because Yb in the optical fiber ³⁺Ion institute emitted fluorescence does not have directionality, and the overwhelming majority can be passed fibre cladding 13 and be penetrated.Thereby, realized the purpose that optical fibre coil type laser freezes.

Cold core 8 of the present invention is cylindrical, and there is the helical flute that is complementary with refrigeration optical fiber 5 external diameters on the surface, and refrigeration optical fiber 6 is wrapped in the groove on the cold core 8.Refrigeration optical fiber 5,6,7 is made of optical fiber jacket 13 clad optical fiber cores 12 fiber cores 12 and optical fiber jacket 13.Fiber cores 12 is a kind of refrigerating materials, and optical fiber jacket 13 is that fluorescence is not absorbed the material that simultaneously pumping laser 2 is had high reflectance.

The present invention adopts the structure of coil form, and refrigerant is an elongated shape, can realize the optical length of advancing that pumping laser is long, helps the absorption of refrigerant to pumping laser, and refrigeration is remarkable.Make that simultaneously anti-Stokes fluorescence is easy to penetrate, the light path of advancing is short.

Claims

1, a kind of optical fibre coil type laser refrigerator, include pump laser (1), refrigeration optical fiber, cold core (8) etc., it is characterized in that the pumping laser (2) that pump laser (1) sends, through transverse mode disarrangement device (3), focused on by optical lens group (4), enter in the refrigeration optical fiber (5), pumping laser (2) from the outgoing of refrigeration optical fiber (7), converged on the speculum (11) by optical lens group (10), after speculum (11) reflection, focus on through optical lens group (10) again and return in the refrigeration optical fiber (7); Described cold core (9) is columniform, and refrigeration optical fiber (6) is on cold core (8), and cold core (8) is possessed good thermally conductive materials and is made by not absorptive pumping laser and anti-Stokes fluorescence; Refrigeration optical fiber 5,6,7 has fiber cores (12) and optical fiber jacket (13) two parts, and fiber cores (12) is the fluorescence refrigerating material, and optical fiber jacket (13) is that fluorescence is not absorbed and pumping laser is had highly reflective material.

2, the helical flute that optical fibre coil type laser refrigerator according to claim 1, the surface that it is characterized in that cold core (8) have the external diameter with refrigeration optical fiber (6) to be complementary, refrigeration optical fiber (6) is in the groove on cold core (8) surface.

3, optical fibre coil type laser refrigerator according to claim 2, the material that it is characterized in that cold core (8) is a monocrystal.

4, optical fibre coil type laser refrigerator according to claim 3, the monocrystal that it is characterized in that cold core (8) is a sodium chloride crystal.

5, optical fibre coil type laser refrigerator according to claim 1 is characterized in that the used material of fiber cores (12) is ZBLANP:Yb ³⁺Glass.