A kind of body Bragg grating mode-locked laser
Technical field
The present invention relates to a kind of laser, especially a kind of body Bragg grating mode-locked laser.
Background technology
The Raman spectrum detection technique is to use laser to obtain the spectral information of material molecule aspect, by the composition of database comparative analysis test substance and the technology of concentration, has powerful ability at harmless Physical Property Analysis and discriminating.Raman spectrum detects the fields such as food security, drug inspection, drugs detecting, judicial expertise, gemstone testing and environment measuring that have been widely used in.Along with the development of practical application request, the Portable Raman optical spectrum detection technique is more and more paid attention to for people in recent years.Portable Raman spectrum detection technique be exactly with Raman technology from laboratory applications push to hand, the technology of portable application.It need not sample preparation, need not isolated area to be checked and clean room, and the material evaluation is carried out at the scene of wanting of what is the need in office that can be easy and convenient in real time.Yet owing to lack compact conformation, mechanically stable is good, and the light source of the laser of high spectral luminance laser as Raman detector can be provided, and makes that the development of Portable Raman optical spectrum detection technique is hindered.
The ordinary semiconductor laser is owing to exist a large amount of zlasing modes in Fabry-Perot (F-P) laser resonator, and breadth of spectrum line surpasses several nanometers, and this will reduce the resolution that Raman spectrum detects greatly; Though and general single-mode laser breadth of spectrum line is less than 1 nanometer, its power output is lower than 200 milliwatts, and the laser of this power is not enough to excite enough strong raman spectral signal usually, is not suitable as the LASER Light Source of portable Raman detector.
Summary of the invention
The present invention seeks to: a kind of not only narrow bandwidth is provided, high power, compact conformation and good mechanical stability, and can improve the body Bragg grating mode-locked laser of spectral luminance.
Technical scheme of the present invention is: a kind of body Bragg grating mode-locked laser comprises
The semiconductor laser is as the light source that produces the broad band laser bundle;
It is characterized in that, also comprise an external resonant cavity, described external resonant cavity comprises the one Bragg grating, this body Bragg grating be coupled described semiconductor laser outgoing laser beam and control the laser beam breadth of spectrum line and dispersion angle and laser beam transverse mode longitudinal mode chosen and control, described body Bragg grating is fixed on the substrate of described semiconductor laser.
Preferably, described external resonant cavity also is provided with collimation lens, and described collimating lens is between described semiconductor laser and described body Bragg grating.
Preferably, described body Bragg grating is a kind of transmission-type body Bragg grating or a kind of reflective body Bragg grating.
Preferably, described body Bragg grating is to sell off the body Bragg grating that glass is made by photo-thermal, sell off the structure that the certain refractive index cycle of formation changes in the glass at this photo-thermal, the body Bragg grating that adopts this photo-thermal to sell off glass can reach and surpass 95% transmission or the diffraction efficiency of reflective-mode, the outgoing laser beam bandwidth can reach 0.1 nanometer even littler, be used for realizing the output of laser of narrowband bundle, the wavelength of laser beam is determined by cycle of grating and the grating inclination angle with respect to incident light.
Advantage of the present invention is:
1. the body Bragg grating directly is fixed on the substrate of described semiconductor laser, can makes described external resonant cavity as much as possible little like this, make whole compact conformation, and improve mechanical stability of the present invention.
. body Bragg grating mode-locked laser of the present invention can be used as for output narrow bandwidth, high-power LASER Light Source.
. this body Bragg grating is conducive to reduce the angle of divergence of laser beam, thereby improves the spatial brightness of laser beam.
Description of drawings
Below in conjunction with drawings and Examples the present invention is further described:
Fig. 1 is the structural representation of transmission-type body Bragg grating mode-locked laser of the present invention;
Fig. 2 is the structural representation of the reflective body Bragg grating of the present invention mode-locked laser;
Wherein: 1 semiconductor laser, 2 external resonant cavities, 2-1 collimating lens, 2-2 transmission-type body Bragg grating, the reflective body Bragg grating of 2-3,2-4 speculum.
Embodiment
Embodiment 1: with reference to shown in Figure 1, a kind of transmission-type body Bragg grating mode-locked laser, comprise a broadband semiconductor laser 1 as LASER Light Source, its outgoing laser beam process is by collimating lens 2-1, the external resonant cavity 2 that transmission-type body Bragg grating 2-2 and speculum 2-4 constitute obtains the stable outgoing laser beam of narrow bandwidth.
This transmission-type body Bragg grating 2-2 can carry out spectrum narrowing and angle Selection to incident laser, selected certain narrow linewidth pattern will be gone out from elementary beam in deflection, and diffraction will not take place in the laser beam of other all patterns, directly pass grating, the laser beam of diffraction does not take place as the main output of external resonant cavity.Collimating lens 2-1 provides the noise spectra of semiconductor lasers coupling that 1 output laser is dispersed naturally and the angular selectivity of transmission-type body Bragg grating 2-2.The transmission-type body Bragg grating 2-2 that adopts among this embodiment has for necessary wavelength and surpasses 95% transmission mode diffraction efficiency, its diffraction direction as shown in Figure 1, speculum 2-4 is with diffraction light reflected back transmission-type body Bragg grating 2-2, and returned in the gain media of semiconductor laser 1 resonant cavity by further diffraction, excited amplification again.Determined by the bandwidth of the breadth of spectrum line of the laser of twice diffraction by transmission-type body Bragg grating 2-2, and its wavelength is by cycle and the inclination angle decision of grating.By the locked mode effect of transmission-type body Bragg grating 2-2, finally can obtain breadth of spectrum line less than the outgoing laser beam of 0.1 nanometer like this.
Embodiment 2, with reference to shown in Figure 2, a kind of reflective body Bragg grating mode-locked laser, comprise a broadband semiconductor laser 1 as excitation source, its outgoing laser beam process is by collimating lens 2-1, the external resonant cavity 2 that reflective body Bragg grating 2-3 constitutes obtains the stable shoot laser of narrow bandwidth.
Reflective body Bragg grating 2-3 can be with the laser reflection feedback of a certain pattern, and along the opposite light path return laser light source of former incident beam, and the laser of other all patterns will be through grating.The reflective body Bragg grating 2-3 that adopts has for necessary wavelength and surpasses 95% reflective-mode diffraction efficiency, and its reflection direction as shown in Figure 2.Collimating lens 2-1 eliminates the high-order scattering light of lasing light emitter outgoing orthogonal direction.The angular selectivity of this reflective body Bragg grating 2-3 is matched with the transverse mode of collimating lens 2-1, and by the feasible light beam return laser light gain media that reflects feedback of suitable adjustment, final this laser beam obtains breadth of spectrum line less than the shoot laser of 0.1 nanometer thus as the main output of external resonant cavity 2.
Adopt transmission-type or reflective body Bragg grating to have following some advantage as the laser of external resonant cavity 2.Because the body Bragg grating is non-dispersivity, incoming laser beam can incide on the body Bragg grating with very little size collimation, still keeps higher diffraction efficiency of grating simultaneously.Therefore the length of the external resonant cavity of laser can shorten greatly, increases the stability of laser, and the laser overall volume is dwindled, and is applicable to portable instrument.The body Bragg grating also helps the angle of divergence that reduces laser beam, thereby improves the spatial brightness of laser beam.
The above only is the embodiment of invention.Protection scope of the present invention is not limited thereto, and anyly is familiar with those skilled in the art in the technical scope that the present invention discloses, and the variation that can expect easily or replacement all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection range that claim was defined.