Ultra-compact diode-pumped single-frequency Ti:sapphire laser

In this Letter, we report on the development of an ultra-compact single-frequency Ti:sapphire laser under direct diode pumping. Single-longitudinal-mode operation is realized from a miniature plane-parallel resonator using a volume Bragg grating as an output coupler. InGaN laser diodes operating at around 470 nm and 490 nm with a combined power of 6.7 W are used as an optical pump. A maximum output power of 700 mW is generated during single-frequency operation at 813.4 nm. A laser linewidth of 2.4 MHz is measured during free-running operation, which is reduced to about 180 kHz when the laser is locked to an external reference cavity.