Browse Prior Art Database

Power Stabilizer and Limiter in Scanlasers

IP.com Disclosure Number: IPCOM000090273D
Original Publication Date: 1969-Mar-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Chang, IC: AUTHOR [+3]

Abstract

The "Fast Digital Scanlaser" is described by Dakss and Powell in IEEE, Quantum Electronics, QE-4, August 1968. There are two basic practical difficulties for scanlasers especially for digital scanlasers using solid state active media. One is the unavoidable spiking oscillation associated with solid state lasers. The other is the intrinsic Q-switch operation in scanlasers. The spiking phenomenon causes the noisy laser output not suitable for constant output signal. The intrinsic Q-switching characteristics in digital scanlasers has undesirable effects. For example, the giant peak power of a Q-switch pulse damages the coating of LiNbO(3) slab used for switching. Also, it takes the relaxation time tau to restore the population inversion in the laser medium after each Q-switching pulse.

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Power Stabilizer and Limiter in Scanlasers

The "Fast Digital Scanlaser" is described by Dakss and Powell in IEEE, Quantum Electronics, QE-4, August 1968. There are two basic practical difficulties for scanlasers especially for digital scanlasers using solid state active media. One is the unavoidable spiking oscillation associated with solid state lasers. The other is the intrinsic Q-switch operation in scanlasers. The spiking phenomenon causes the noisy laser output not suitable for constant output signal. The intrinsic Q-switching characteristics in digital scanlasers has undesirable effects. For example, the giant peak power of a Q-switch pulse damages the coating of LiNbO(3) slab used for switching. Also, it takes the relaxation time tau to restore the population inversion in the laser medium after each Q-switching pulse. The long relaxation time in solid state lasers, for example, in Nd:YAG the time tau = 250 mu sec limits the switching speed of the Nd:YAG scanlaser to be less than 4kc. Furthermore, the Q-switching operation only provides pulse outputs for the scanlaser which might require constant output for its applications.

As shown in the drawing, this arrangement uses feedback loss control to stabilize and to limit the output of a solid state scanlaser in order to eliminate the spiking phenomenon and to prevent the laser from Q-switching operation. The arrangement consists of electro-optic loss modulator 10, Brewster angle plate 12 and a feedback loop containing photodetector 14, and amplifier 16 connected to electro-optic loss modulator 10. Plate 12 serves to polarize the laser light and couple the cross-polarized light into photodetector 14. The cross-polarized light can be due to either the natural birefringence of the laser rod or the induced phase retardation...