Multi-active region laser diode with a narrow beam divergence angle

A novel large optical cavity laser diode, which consists of multi-active regions cascaded together through tunnel junctions, is proposed. After growing the epi-layers with LP-MOCVD system on GaAs substrate, the ridge waveguide laser structure is fabricated, and it shows a transverse divergence angle as low as 14.4°. This work was supported by special foundations for major state basic research project of China(G20000683-02)     

Design and experiment of a laser ionization source for ion mobility spectrometer

Ion mobility spectrometry (I MS) is based upon theseparation of gas phaseionsthroughsize-to-charge rath-er than mass-to-chargeratios[1].Morerecentlythe appli-cationsinindustry and environment have increased,notonly because of the si mplicity of theinstrum…     

Novel method to optimize the distributed pump powers in a kilowatt ytterbium-doped double-clad fiber laser

High-power ytterbium-doped fiber laser has attractedmuch attention recently in commercial and military ap-plications due to its high efficiency,compactness andhigh beam quality.In kilowatt power domain,the heatdissipation will play an i mportant role and …     

Thermal effects on structure and photoluminescence properties of diamond-like carbon films prepared by pulsed laser deposition

With their unique properties such as high hardness ,lowfriction,chemical inertness and optical transparency,Diamond-like carbon(DLC) fil ms are usedina wide ar-ea of industrial applications ,as a protective coating insuch areas as optical windows ,magneti…     

LD side-pumped intracavity frequency-doubled high Nd：YAG green laser based on acousto-optic Q-switch

A highly efficient and high power green laser generated by intracavity frequency doubling of a diode-sidepumped Q-switched Nd：YAG laser has been demonstrated. In the simple L-shaped cavity geometry,the maximum green output power of 28.5 W was obtained with a pulse width of 95 ns at a pulse repetition rate of 10 kHz by using a LBO crystal for frequency doubling,corresponding to a conversion efficiency of 11% from diode pump power to pulse green power. At a pulse repetition rate of 1 kHz,6.9 mJ of pulse energy,25 ns of pulse duration and 276 kW of peak power were obtained.     

High power collimated diode laser stack

Compared with other kinds of lasers ,high power di-odelaser has many advantages suchas highelectro-opti-cal efficiency,compact structure,longlifeti me andso on.As alaser source,diode laser is sufficient for many dif-ferent applications suchas pumping of s…     

Novel kind of lyot birefringent tunable filters

The Lyot filter is a monocolour birefringent filterwhichis invented by the French physicist Lyot for theresearches of astronomy,especiallyfor observingthe so-lar corona.Becausethe birefringent filter can be designedof the special optical characters such a…     

High stable power control of a laser diode

For a high precise sensing and measuring system,theerror of measurement resulting fromthe fluctuation ofthe light source must be considered[1-3].The main noisesources include fluctuation of current source,self-heat ,aging and theintrinsic noises of a lase…     

Experimental study of thermal lensing of Nd：YAG laser

Beamfocusing and higher-order wavefront distortiondue to heat dissipationinalaser gain mediumarei mpor-tant considerationsinthe design of solid-statelasers be-cause wavefront distortion can profoundly influence theperformance of a givenlaser design.Althou…     

Supercontinuum generation pumped by a regeneratively mode-locked fiber laser

Supercontinuum（SC） generation in a dispersion-shifted fiber（DSF） pumped by a 10 GHz regeneratively mode-locked fiber laser（RMLFL） is presented. Optimization of pump wavelength leads to a 20 dB bandwidth of 58.73 nm,which covers the whole C band and part of L band. Using an angle-tuning thin film filter, multi-wavelength and pico-second pulse trains of low chirp could be chosen from the SC spectrum. Amplified spontaneous emission（ASE） induced degeneration of the achieved pulse trains is observed and discussed.     

Novel simulation method for fiber Bragg grating under inhomogeneous strain fields

The spectra of fiber Bragg grating （FBG） in inhomogeneous strain fields are distorted due to its inhomogeneity of both the periods and the effective refractive index. The couple mode theory and the Runge-Kutta method can be employed for exact simulation of the spectrum of Bragg grating in such field, but the convergence speed is slow. On the other hand, although the transfer matrix method could be used with higher convergence speed, the precision is poor because of the neglect of the grads of strain change. By improving the FBG equivalent period, a novel simulation method based on a modified transfer matrix method is proposed, which has the advantage of quick-convergence as well as good accuracy.     

Experimental study of thermal lensing of Nd：YAG laser

Beamfocusing and higher-order wavefront distortiondue to heat dissipationinalaser gain mediumarei mpor-tant considerationsinthe design of solid-statelasers be-cause wavefront distortion can profoundly influence theperformance of a givenlaser design.Althou…     

Theoretical analysis of radiation-balanced double clad fiber laser

Recently,double clad fiber lasers with an output ofkilo-watt power have been reported[1].Thermal prob-lems such as thermal stressinducedfracture,decreasingof quantumefficiency andthermal lens effect are seriousinthis kind of high powerfiberlaser[2].In1995 ,fluores-cence cooling in Yb doped ZBLANP(ZrF4-BaF2-LaF3-AlF3-NaF-PbF2) glass was realizedfor thefirst ti me[3].Consequently,a section of Yb doped ZBLANP glass fi-ber laser was cooled from298 Kto 282 Kin the vacu-um[4].According t…     

Free electron laser based on the Smith-Purcell radiation

The electromagnetic radiation is sti mulated when anelectron beampasses a metallic periodic structure like adiffraction grating at a fixed distance close to the sur-face.This phenomenon is known as the Smith-Purcelleffect .The radiation mechanism was pred…     

Mechanism of the genetic mutagenesis effects of far infrared ray laser

We have analyzed the order-disordering variance due to resonance effect and the nonlinear behavior of far infrared ray laser （FIRL）-biological system interaction. The analytic results show that the interaction between the living biological system and FIRL can produce resonance excitation effect, and so the original high ordered state of the system can be destroyed and thus the conformation variation in the system can be produced under further action of the laser. In addition, we have analyzed the nonlinear properties of the FIRL bio-molecule interaction and explained the mutagenesis effects of FIRL. The theoretic analysis is consistent with the results of FIRL mutagenesis breeding test.     

Preparation of Nd-doped gadolinium-gallium garnet laser ceramic powder by sol-gel method

Gadoliniumgalliumgarnet(GGG)existsinthe cubicformand has a garnet structure.Its excellent propertiesmakeit theideal substrates for YIGand YIG-like mag-neto-optical epitaxial fil ms,which are widely usedinthefields of optical isolators,optical waveguide an…     

Novel algorithm of finding good candidate pre-configuration cycles in survivable WDM mesh network

Pre-configuration Cycle (p-cycle) is a promising ap-proach for protecting working capacities in WDMnet-works because of its ability to achieve ring-like recoveryspeed while maintaining the capacity efficiency of amesh-restorable network[1].The first and t…     

Numerical analysis of thermal distortion of the mirror in space-to-ground laser communication links

Thereis cold-heat exchange under the large tempera-ture gradient in the space environment ,andin space-to-ground laser communication links the optical reflectorson a satellite in orbit someti mes need to be placed out-side the capsule.Therefore,tremendous thermal distor-tions will occur onthe optical mirror surface,which maybring shift andspreading ofits reflectedfocus andthere-by influences the performance of space-to-ground lasercommunicationlinks . Although there are many reports on thermal…     

L-band tunable erbium doped fiber ring laser using fiber loop mirror filters

We present a novel and efficient L-band wavelength-tunable Er^3＋ doped fiber laser of ring structure. In the cavity two segments of Er^3＋ doped fiber and a fiber Bragg grating are used to improve pump efficiency. Tunable filters based on fiber loop mirrors are also applied inside the cavity to act as both a wavelength selector and a line-width compressor. Using these techniques, a tunable laser with tuning range up to 42 nm, output power larger than 1 mW, power uniformity controlled within 1.75 dB and side mode suppression ratio about 40 dB is achieved.     

Thermal analysis of laser diode module by an equivalent electrical network method

Heat generation and dissipationin LDpackages with-out TEC have been investigated both analytically andexperi mentally[1-4].However,the thermal analysis ofLDMincorporated with a TEC has not yet been suffi-cientlyinvestigated.Afinite element methodtoanalyse…