Hackaday · Creativity & design

Benchtop Laser Enhanced to Megawatt Peak Power

A Q-switch was added to a benchtop laser to significantly increase its peak power, though total energy output decreased.

A Q-switch, an optical attenuator, limits stimulated emission in a laser cavity, allowing energy to build up. When the Q-switch is removed, the cavity releases this energy in a very short, powerful pulse. This process does not increase the total energy per shot but releases it much faster.

Using chromium-doped yttrium aluminum garnet crystals as Q-switches, performance was compared. Without a Q-switch, the laser produced a 150 µs pulse with 137 mJ energy and under 1 kW peak power. With a Q-switch, the pulse shortened to 14 ns, increasing peak power to 1.3 MW, but reducing total energy to 77 mJ.

Testing with an absorption meter showed that greater Q-switch absorption generally increased peak power, reaching 2.25 MW at 92% absorption.

The increased peak power did not enhance cutting ability on metal targets, as the short pulse primarily ablated the surface. However, the energy was sufficient to ionize air or shatter glass at the focal point.

This Q-switch upgrade follows a previous enhancement to the laser's gain medium.

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