ALMA Memo # 396 : A Photonic MM - Wave Reference and Local Oscillator Source

We report further progress on the development of a photonic mm-wave waveguide source suitable for application as a phase reference and as a local oscillator. The mmwave power was generated in a W-band waveguide mount by the beating of two 1.55 μm laser beams in a modified commercial photodiode. Maximum optical to mmwave power conversion efficiency of 1.8% was measured at 75 GHz, where an input power of +10 dBm yielded a non-saturated output power of –7.5 dBm. Measured output powers fell approximately as frequency above 100 GHz, decreasing from about –10 dBm at 100 GHz to –40 dBm at 625 GHz. We remark that the mount is non-optimised for frequencies above 110 GHz, and so these measurements represent a lower limit on the available power.