Abstract
Fabrication of capacitive-Al-mesh output coupler for the optically pumped FIR laser is studied. With use of metal mesh sheet for a deposition mask, aluminium is directly deposited on the substrate of which materials are either crystal quartz, silicon, or germanium.To construct well-defined capacitive mesh structures, thedeposition mask is designed so as to realize complete contact with the substrate. Output characteristics of the coupler are examined with an optically pumped 251 μm CH3OH laser as follows: (1) FIR output powers of 34 m Wat 163 μm, 18 m Wat 251 μm, and 8 m Wat 469 μm, are extracted from a 25W pump (2) the coupler is capable ofenhancing a particular oscillation line by adjusting mesh parameters; (3) oscillation modes in the cavity tuning curve are clear enough to assign their wavelengths easiliy.
