Significant improvement in frequency doubling efficiency of a cw output of a GaAlAs laser diode is described. Up to 0.72 mW of 421 nm power was generated by illuminating a KNbO3 crystal with a 270 mW diffraction-limited beam generated by an externally injection-locked laser diode array, operating in a single-mode and single-far-field lobe.
The interaction of high-intensity laser beams with metals has been analyzed on the basis of detailed quantitative measurements of the energy balance. The interaction of normal (not Q-switched) pulses with energies ranging from 1 to 30 J from a Nd-doped glass laser with metals having a variety of thermal and optical properties was studied. The time-dependent radiation reflectance of the metals, measured during the laser pulse, is found to account for most of the incident power in the initial stages of the interaction. As time progresses, much of the incident power is absorbed. It was found that the greatest part of the absorbed radiation energy is used to remove material in the liquid and vapor phases. Due to a large heat of vaporization for most metals, the amount of energy required to remove a given mass is strongly dependent on the relative amounts removed in the liquid and vapor phases. To determine this ratio, the total mass of material and the mass of molten material were measured.
Single narrow far-field lobe emission is observed in an injection-locked high-power broad stripe laser. Lobe widths below 1.3 times the diffraction limit for the 160-μm-wide stripe were observed for power levels up to 1.0 W. Decrease in the power contained within the narrow lobe for high laser bias currents is observed and is attributed to self-focusing effects in the active region. Small-signal external power gain of 21 dB was measured.
The crossed Porro prism configuration improves the stability of the alignment of the laser resonator; however, the resultant phase shift alters the characteristics of the electrooptical Q-switch. An analysis of the operational characteristics, such as variable outcoupling, extinction ratio, and prelasing boundaries, is presented along with experimental data. An electrooptically Q-switched Nd:YAG laser with a crossed Porro prism resonator, which successfully withstands severe physical environments, has been developed and demonstrated.
The 842-nm diffraction-limited emission from an injection-locked laser diode array was frequency doubled using a monolithic spherical-mirror KNbO3 crystal cavity. Maximum unidirectional external 421 nm power of 24 mW was generated with 167 mW of pump power. Maximum total internal second-harmonic power and conversion efficiency of 64 mW and 45% were obtained. Effects of heating in the crystal are described.
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