Topical Papers on Microchip Lasers and Applications. Generation of Narrow-Band Millimeter-Wave Radiation by Means of a Two-mode Microchip Laser.

The generation of narrow-band millimeter-wave radiation has been achieved by photomixing two longitudinal modes in a two-mode microchip laser. The two modes were frequency-converted to their second harmonics using an external cavity, then focused onto the photoconductive gap of an LTG-GaAs photomixer . A millimeter wave was generated from the photoconductive antenna and examined using a spectrum analyzer with a millimeter-wave mixer. The linewidth observed for the millimeter wave was 430 Hz at 101 GHz, which is only 1/230 the width of the individual laser modes. This narrow linewidth of the millimeter wave can be attributed to the cancellation of most of the frequency fluctuations embedded in the two modes due to their sharing the same volume in the same cavity.