Pulse Stretching In A Q-switched Ruby Laser System With Optic-electronic Feedback Circuit

Laser is increasingly being applied in many fields now, such as ruby laser, alexandrite laser, diode laser and Nd:YAG laser. Along with the development of the laser technology and the broaden of the apply fields, the technology of laser pulse stretching is also developing. The term pulse stretcher in this study is ideally suited for nanosecond-long laser pulses and is different from the time-bandwidth product type of pulse stretcher that is routinely used in ultrafast (femtosecond) laser systems. Several concepts of pulse stretching with electro-optical devices have been reported. However, there are few pulse-stretching systems designed to reduce the high peak powers of nanosecond-long laser pulses from QS lasers. Many of these techniques rely on complicated and often expensive electro-optic modulators to control the intracavity pulse buildup in the laser. This paper is study on the pulse-stretching on the Q-switched ruby laser with a new optic-electron feedback circuit.This paper emphasises on the works as follows:1. It calculates the two-level energy system laser rate equation, combining the feedback circuit. We could, from these, get the conditions on the laser pulse stretching.2. The laser cavity is designed with double KD*P crystals. Theπ/2 phase-difference voltage that the single crystal generates is above 2500v, so we can not get the photoelectricity negative feedback circuit. In comparation with the above case, the double-crystal circuit connected in series generates theπ/2 phase-difference voltage which is about 1kv, meanwhile, the feedback voltage falls down largely.3. It simulates the variation of the inverted population in the laser cavity, with the detect laser rod emitting the radiofluorescence. In order to output laser when the inverted population in the cavity accumulates at the most. In this case, we could get much steady laser output.4. We designed a new style photoelectricity negative feedback circuit. It transfers the recuperative optical signal to voltage signal, to obtain a real-time control on the photoelectric crystal voltage. Further more, it controls the relation between the dissipation and the increment in the laser cavity. Only through this way, we can gain the stretched Q-switched laser pulse.Ascribe to the experience, finally, we obtain a 200ns-pulse width Q-switched laser pulse.