In this paper, we present a theoretical model to describe the passively-Q output characteristics of quasi-three level Ho3+-doped Fluorotellurite fiber lasers. According to the model, we have studied the factors impacting on the output characteristics of the laser through numerical simulation method. The calculating program of the theoretical model is written using the Matlab language. We obtain the passively-Q output laser with the pulse repetition rate of 13.1 kHz, pulse width of 28.63ns, peak power of 25W, and pulse energy of 0.34 μJ at the pump power of 0.1W. When the pump power increases, the pulse width of the laser decreases, the pulse repetition rate linearly increases, both the pulse energy and the peak power also increases. The pulse width of the laser linearly increases and the pulse energy increases when the length L does. When the output coupler transmission T increases, both the pulse width and the peak power of the laser decrease. The pulse energy of the laser firstly increases and then decreases when the output coupler transmission T does. We qualitatively analyze what causes the change laws of the outputlaser characteristics, such as the pulse width and the pulse energy.
High power AlGaInP laser diodes (LDs) and bars emitting at about 685 nm have been fabricated. The epitaxial structures, including the AlInP cladding layer, asymmetric waveguide and single compressive-strained quantum well, were designed to optimize the thermal performance. The transparent window structure formed by Zn diffusion was employed to increase the output power of AlGaInP LDs. A maximum power of 4.9 W was realized for the single emitter LDs without catastrophic optical damage. Using micro-channel heat sinks, an array stacked with six 1-cm bars showed an output power of more than 300 W with 40% conversion efficiency.
Highly uniform solid-phase Zn-diffusion technique was developed to fabricate transparent windows for 650 nm red laser diodes (LDs). The maximum output power was up to 120 mW, which is three times higher than that for LDs without window structure. The LDs showed excellent thermal characteristics and aging reliability with TO-can package. The characteristic temperature was estimated to be 85 K in the temperature range of 25~65 °C. The LDs showed stable operation of 10 mW at a high temperature of 75 °C. After aging test of 2000 h, the elevated operation current was less than 3%, compared to the initial value. The predicted life time was over 10000 h for 10 mW operation at 75 °C.
In this paper, we present a high power TM Polarized GaAsP laser diode of 808nm wavelength. For high power and narrow beam divergence, an asymmetry broad waveguide structure and a tensile strained GaAsP quantum well were used and the epilayers were grown by low-pressure metalorganic chemical vapor deposition. We have obtained an optical power of 20.86W at 20A without COMD and the vertical farfield of 27°. It is expected that Al-free GaAsP quantum well laser diodes will have good reliability
without any facet treatment.
With the support of state key project, Shandong Huaguang Optoelectronics Co. Ltd. realizes the mass production of low threshold current 650nm GaInP/AlGaInP semiconductor laser chips, rapidly. At present, six million 650nm LD chips can be produced per month. The lowest threshold current at 25°C is 7.4mA. The slope efficiency reaches 1.1mW/mA and the output power is 34mW at 40mA CW operation.