Demonstration of a GaAs-based 1550-nm continuous wave photomixer

摘要

An Er:GaAs-based 1550-nm CW photomixer is demonstrated. The related mechanism is extrinsic photoconductivity with optical absorption between the localized deep levels created by the Er and the extended states above the conduction band edge of GaAs. With the power boost made possible by a fiber-coupled erbium-doped-fiber amplifier, the Er:GaAs photomixers, operating at 1550 nm, radiate THz power levels easily measured by a Golay cell, and display a power spectrum having a -3 dB roll-off frequency of 307 GHz. This corresponds to a photocarrier lifetime of 520 fs, in good agreement with a previous measurement of the bandwidth of the same material in a photoconduc-tive switch.