Single-frequency microchip Nd lasers.

Optically pumped, single-frequency, Nd-doped, solid-state lasers have been constructed using flat–flat cavities, which were diced from large dielectrically coated wafers of various crystals. For example, a Nd:YAG laser with a cavity length of 730 μm has operated at room temperature in a single longitudinal mode from a threshold of less than 1 mW to greater than 40 times the threshold. The slope efficiency was greater than 30%. Heterodyne measurements showed an instrument-limited linewidth of 5 kHz. The microchip lasers demonstrate ways to reduce greatly the cost and complexity of fabricating small lasers and electro-optic devices.