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High-power GaAs-based semiconductor lasers are the most efficient source of energy for converting electrical into optical power. 940nm diode lasers are used directly or as pump sources for Yb:YAG solid-state lasers, and are widely used in laser cladding and other fields. Improving electro-optic conversion efficiency and reliable output power are urgent requirements for current research hotspots and industrial laser systems. In this paper, we use an asymmetric epitaxial structure of InGaAs/AlGaAs, which reduces the optical loss and resistance, and adopt better cavity surface technology to present 940nm 1-cm quasi-continuous micro-channel cooling (MCC) laser bars. The lasers are tested under a high duty cycle of 9.6% (600us,160Hz) at 25°C with output power of 660.05W, electro-optic conversion efficiency of 64.71% at 600A and slope efficiency of 1.16 W/A. The peak efficiency reaches 72.4%. The increased efficiency results from a lower threshold current and a lower series resistance. Furthermore, the output power of 1025W (1000A) has been confirmed at a duty cycle of 4% (400us,100Hz).

With the improvement of output power, efficiency and reliability, high power semiconductor lasers have been applied in more and more fields. In this paper, a conduction-cooled, high peak output power semiconductor laser array was studied and developed. The structure and operation parameters of G-Stack semiconductor laser array were designed and optimized using finite element method (FEM). A Quasi-continuous-wave (QCW) conduction-cooled G-Stack semiconductor laser array with a narrow spectrum width was fabricated successfully.

Laser cladding has become a useful tool in materials processing for improving the surface properties of the substrate materials, and has been widely used in industry in recent years. In this paper, we study the 3000W CW laser cladding system based on the high power diode lasers. The beam control method is proposed to reduce the collimated beam pointing errors caused during the packaging of the laser stack. At the input current of 84A, the output power and the optical coupling efficiency of this laser cladding system are 3738W and 93.7%, respectively, and at work face the beam spot size is 2.5mm*7.9mm with symmetry intensity distribution. The laser cladding system is also used in cladding the nickel powder onto the iron substrate and the nickel powder can be clothed onto steel plate uniformly.

A novel 980nm bottom-emitting VCSELs array with high power density and good beam property of Gaussian far-field distribution is reported. This array is composed of 5 symmetrically-arranged elements of 200μm,150μm and 100μm-diameter , with the center spacings of 300μm and 250μm respectively. The maximum power is 880mW at a current of 4A, corresponding to 1KW/cM 2 average optical power density. The differential resistance is 0.09Ω with a threshold of 0.56A. The novel array is compared with a 300μm-aperture-size single device and a 4 * 4 2-D array with 50μm element aperture size and 250μm centre spacing. The three devices have the same lasing area. The conclusion is that the novel array is better in the property of output power, threshold current, lasing spectra, far-field distribution etc.

Whispering-Gallery-Mode (WGM) photonic crystal microcavity is a kind of photonic crystal application and can potentially be used for miniaturized photonic devices, such as thresholdless lasers. In this paper we study the WGM of photonic crystal microcavities focusing on the so called H2 cavities which are formed by removing seven air holes. The WGM in these large-size cavities has some advantages compared with single defect WGM in the view of real device applications. We further add a central air hole in the cavity region to analyze the effect on WGM in the microcavity by finite difference time domain (FDTD) and plane wave expansion (PWE). It is found that the tolerance of WGM is large enough for the fabrication of electrical injection structure.