Diode-pumped room-temperature continuous wave Tm3+ doped Lu2SiO5 laser

We report on room temperature laser actions of a novel thulium-doped crystal Tm center dot Lu2SiO5 (LSO) under diode pumping. An optical optical conversion efficiency of 12% and a slope efficiency of 21% were obtained with the maximum continuous wave (CW) output power of 0.67 W. The emission wavelengths of Tm LSO laser were centered at 2058.4 nm with bandwidth of similar to 13.6 nm.

Continuous-wave and passively mode-locked Yb : GYSO lasers pumped by diode lasers

We report both continuous-wave and passively mode-locked laser actions in a Yb3+-doped gadolinium yttrium oxyorthosilicate Yb:GdySiO(5) (Yb:GYSO) crystal. Continuous-wave (CW) laser operations were compared under different pump conditions with high-power diodes of different wavelengths and fiber cores. CW mode-locking was obtained with a semiconductor saturable absorber mirror.

Continuous-wave and Q-switched operation of a resonantly pumped Ho:YAlO3 laser

We demonstrated continuous-wave ( CW) and Q-switched operation of a room-temperature Ho: YAlO3 laser that is resonantly end-pumped by a diode-pumped Tm: YLF laser at 1.91 mu m. The CW Ho: YAlO3 laser generated 5.5 W of linearly polarized (E parallel to c) output at 2118 nm with beam quality factor of M-2 approximate to 1.1 for an incident pump power of 13.8 W, corresponding to optical-to-optical conversion efficiency of 40%. Up to 1-mJ energy per pulse at pulse repetition frequency (PRF) of 5 kHz, and the maximum average power of 5.3-W with FWHM pulse duration of 30.5 ns at 20 kHz were achieved in Q-switched mode. (C) 2008 Optical Society of America.

Diode-pumped continuous wave and Q-switched operation of a c-cut Tm,Ho:YAlO3 laser

We report on a diode-pumped, cryogenic and room temperature operation of a Tm,Ho:YAlO3 (c-cut) laser. In a temperature of 77 K, an optical-optical conversion efficiency of 27% and a slope efficiency of 29% were achieved with the maximum continuous-wave (CW) output power of 5.0 W at 2.13 mu m. Acousto-optic switched operation was performed at pulse repetition frequency (PRF) from 1 kHz to 10 kHz, the highest pulse energy of 3.3 mJ in a pulse duration of 40 ns was obtained. In room temperature (RT), the maximum CW power of Tm,Ho:YAlO3 laser was 160 mW with a slope efficiency of 11% corresponding to the absorbed pump power. (C) 2008 Optical Society of America.

High-average-power and high-conversion-efficiency continuous wave mode-locked Nd : YVO4 laser with a semiconductor absorber mirror

A high-power continuous wave (cw) mode-locked Nd:YVO4 solid-state laser was demonstrated by use of a semiconductor absorber mirror (SAM). The maximum average output power was 8.1 W and the optic-to-optic conversion efficiency was about 41 %. At the maximum incident pump power, the pulse width was about 8.6 ps and the repetition rate was 130 MHz. Experimental results indicated that this absorber was suitable for high power mode-locked solid-state lasers. (C) 2006 Elsevier Ltd. All rights reserved.

Room-temperature continuous-wave operation of InAs quantum-wire laser on InP(001) substrate

A self-assembled quantum-wire laser structure was grown by solid-source molecular beam epitaxy in an InAlGaAs-InAlAs matrix oil InP(001) substrate. Ridge-waveguide lasers were fabricated and demonstrated to operate at a heatsink temperature tip to 330 K in continuous-wave (CW) mode. The emission wavelength of the lasers with 5 mm-long cavity was 1.713 mu m at room temperature in CW mode. The temperature stability of the devices was analysed and the characteristic temperature was found to be 47 K in the mnge of 220-320 K.

High power continuous-wave operation of self-organized In(Ga)As/GaAs quantum dot lasers

Quantum dot (QD) lasers are expected to have superior properties over conventional quantum well lasers due to a delta-function like density of states resulting from three dimensional quantum confinements. QD lasers can only be realized till significant improvements in uniformity of QDs with free of defects and increasing QD density as well in recent years. In this paper, we first briefly give a review on the techniques for preparing QDs, and emphasis on strain induced self-organized quantum dot growth. Secondly, self-organized In(Ga)As/GaAs, InAlAs/GaAlAs and InAs/InAlAs Qds grown on both GaAs and InP substrates with different orientations by using MBE and the Stranski-Krastanow (SK) growth mode at our labs are presented. Under optimizing the growth conditions such as growth temperature, V/III ratio, the amount of InAs, InxGa1-xAs, InxAl1-xAs coverage, the composition x etc., controlling the thickness of the strained layers, for example, just slightly larger than the critical thickness and choosing the substrate orientation or patterned substrates as well, the sheet density of ODs can reach as high as 10(11) cm(-2), and the dot size distribution is controlled to be less than 10% (see Fig. 1). Those are very important to obtain the lower threshold current density (J(th)) of the QD Laser. How to improve the dot lateral ordering and the dot vertical alignment for realizing lasing from the ground states of the QDs and further reducing the Jth Of the QD lasers are also described in detail. Thirdly based on the optimization of the band engineering design for QD laser and the structure geometry and growth conditions of QDs, a 1W continuous-wave (cw) laser operation of a single composite sheet or vertically coupled In(Ga)As quantum dots in a GaAs matrix (see Fig. 2) and a larger than 10W semiconductor laser module consisted nineteen QD laser diodes are demonstrated. The lifetime of the QD laser with an emitting wavelength around 960nm and 0.613W cw operation at room temperature is over than 3000 hrs, at this point the output power was only reduced to 0.83db. This is the best result as we know at moment. Finally the future trends and perspectives of the QD laser are also discussed.

Continuous-wave operation of GaN based multi-quantum-well laser diode at room temperature

Room-temperature operation of cw GaN based multi-quantum-well laser diodes (LDs) is demonstrated. The LD structure is grown on a sapphire (0001) substrate by metalorganic chemical vapour deposition. A 2.5 mu m x 800 mu m ridge waveguide structure is fabricated. The electrical and optical characteristics of the laser diode under direct current injection at room temperature are investigated. The threshold current and voltage of the LD under cw operation are 110mA and 10.5V, respectively. Thermal induced series resistance decrease and emission wavelength red-shift are observed as the injection current is increased. The full width at half maximum for the parallel and perpendicular far field pattern (FFP) are 12 degrees and 32 degrees, respectively.

532 nm continuous wave mode-locked Nd:GdVO4 laser with SESAM

We obtained continuous wave mode-locked Nd-GdVO4-KTP laser with a SESAM. This is the first report of CW mode-locked Nd GdVO4-KTP laser with a SESAM to our knowledge. 396mw CW mode-locked pulse is achieved at the incident power of 7.653 W, with the repetition about 95 MHz. The pulse duration is assumed to be 5.5 ps, this is the shortest green pulse of 532 nm with SESAM. (c) 2009 by Astro Ltd. Published exclusively by WLLEY-VCH Verlag GmbH & Co. KGaA

End-pumped continuous-wave passively modelocked Nd : YVO4 laser with low pump power

A simple cw mode-locked solid-state laser, which is end-pumped by a low-power laser diode, was demonstrated by optimizing the laser-mode size inside the gain medium. The optimum ratio between mode and pump spot sizes inside the laser crystal was estimated for a cw mode-locked laser, taking into account the input pump power. Calculation and experiment have shown that the optimum ratio was about 3 when the pump power is 2 W, which is different from the value regularly used in passively mode-locked solid-state lasers. This conclusion is also helpful in increasing the efficiency of high-power ultrashort lasers. (C) 2006 Society of Photo-Optical Instrumentation Engineers.

Room-Temperature Continuous-Wave Operation of InGaN-Based Blue-Violet Laser Diodes with a Lifetime of 15.6 Hours

We report our recent progress of investigations on InGaN-based blue-violet laser diodes (LDs). The room-temperature (RT) cw operation lifetime of LDs has extended to longer than 15.6 h. The LD structure was grown on a c-plane free-standing (FS) GaN substrate by metal organic chemical vapor deposition (MOCVD). The typical threshold current and voltage of LD under RT cw operation are 78 mA and 6.8 V, respectively. The experimental analysis of degradation of LD performances suggests that after aging treatment, the increase of series resistance and threshold current can be mainly attributed to the deterioration of p-type ohmic contact and the decrease of internal quantum efficiency of multiple quantum well (MQW), respectively.

Kinetic model of continuous-wave flow chemical lasers

In this paper an analysis of the kinetic theory of the continuous-wave flow chemical lasers(CWFCL) is presented with emphasis being laid on the effects of inhomogeneous broadeningon CWFCL's performance. The results obtained are applicable to the case where laser fre-quency is either coincident or incoincident with that of the eenter of the line shape. This rela-tion has been,compared with that of the rate model in common use. These two models are almostidentical as the broadening parameter η is larger than 1. The smaller the value of η, thegreater the difference between the results of these two models will be. For fixed η, the dif-ferences between fhe results of the two models increase with the increase of the frequencyshift parameter ξ. When η is about less than 0.2. the kinetic model can predict exactly the in-homogeneous broadening effects,while the rate model cannot.

Compact continuous-wave blue lasers by direct frequency doubling of laser diodes with periodically poled lithium niobate waveguide crystals

A compact continuous-wave blue laser has been demonstrated by direct frequency doubling of a laser diode with a periodically poled lithium niobate (PPLN) waveguide crystal. The optimum PPLN temperature is near 28 degreesC, and the dependence of waveguide crystals on crystal temperature is less sensitive than that of bulk crystals. A total of 14.8 mW of 488-nm laser power has been achieved. (C) 2005 Optical Society of America.