Study On Laser-Diode End-and-Side Composit-Pumped Solid-State-Lasers Technology

A new pumping method, the laser-diode end-and-side composite-pumping technique, is first put forward in laser-diode-pumped solid-state lasers (DPL).The flat-topped beam, coupled by nineteen fibers in circle and then shaped by lens, is used as the end-pumping light to control the space distribution of the oscillation light for improving the beam quality and compressing the pulse width. The three liner LDs side-pumped symmetry is used as the side-pumping light to raise the pumping power. The output beam with big power, good beam quality, narrow pulse width, high peak power and being controllable is acquired.The end-and-side composite-pumping structure is given. The model of the pumping intensity is founded. Performance of the gain distribution inside the Nd:YAG crystal and the thermal lens effect is also analyzed. Two aspects, the controlling function of the space distribution of the end-and-side composite-pumping light on the oscillation light and the acoustics-optical Q-switched feature of the end-and-side composite-pumped DPL are studied in experiments, theory and numerical calculation.Four main conclusions below have been received.1 In a laser-diode end-and-side composite-pumped DPL, the proportion of the end-pumping power in the total pumping, which is defined as the occupancy of the end-pumping power, is an important factor to influence the gain distribution. With the total pumping power and the pumping structure fixed, we can control the gain space distribution by changing the occupancy of the end-pumping power. But both the single end-pumping and the single side-pumping have not this character.2 The thermal effect in the end-and-side composite-pumping can be approximated by an equivalent lens.By raising the occupancy of the end-pumping power, we can decrease the influence of the thermal lens effect on the radius of the oscillation beam and thermal induced losses.3 Using the end-pumping light in a composite-pumped DPL raises the competition ability of the zero level mode remarkably, improves the output beam quality greatly. With the total pumping-power and the pumping structure fixed, the larger the end-pumping power, the stronger the competition ability of the zero level mode, and the better the output beam quality. So we can improve beam quality and control the oscillation light by changing the proportion of the end-pumping power.4 The pulse width in a composite-pumped DPL is obviously narrower than that in a single side-pumped DPL, and the peak power is remarkably higher. With the total pumping-power and the pumping structure fixed, the larger the occupancy of the end-pumping power, the higher the pulse peak power, and the narrower the pulse width.