We investigate the different characteristics of the intensity noise of a laser-diode-pumped single-frequency ring Nd:YVO (4) laser and a Nd:YVO (4)-KTP green laser. By use of an optoelectronic feedback circuit connected directly to the pump current of the laser diode, the low-frequency intensity noise of the intracavity frequency doubler was suppressed to some extent.

We demonstrate operation of a GaAs-based self-aligned stripe (SAS) distributed feedback (DFB) laser. In this structure, a first order GaInP/GaAs index-coupled DFB grating is built within the p-doped AlGaAs layer between the active region and the n-doped GaInP opto-electronic confinement layer of a SAS laser structure. In this process no Al-containing layers are exposed to atmosphere prior to overgrowth. The use of AlGaAs cladding affords the luxury of full flexibility in upper cladding design, which proved necessary due to limitations imposed by the grating infill and overgrowth with the GaInP current block layer. Resultant devices exhibit single-mode lasing with high side-mode-suppression of >40 dB over the temperature range 20 °C-70 °C. The experimentally determined optical profile and grating confinement correlate well with those simulated using Fimmwave.

Second harmonic generation from 858nm to 429nm has been investigated at room temperature by using Potassium Niobate (KNbO3) crystal. The optimum parameters for nonlinear conversion in our designing singly resonant, external ring cavity pumped by the Ti: Sapphire laser are established. In addition, we investigate the conversion efficiency over a range of operating conditions. When the cavity is scanned, 1 70 mW (235mW corrected for losses of the output mirrors) of blue light at 429nm is produced with 600mW of pump power near 858 nm whereas 137 mW is generated with 565 mW of pump when the cavity is locked.

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