Photonic local oscillators for millimeter- and submillimeter-wave receivers

In this paper a new scheme called "photonic LO", in which the LO signal can be generated with a photodetector by mixing two optical signals differing in the frequency by the required LO frequency is described The photonic LO can greatly simplify the LO system in a large radio interferometer system such as Atacama large millimeter-submillimeter array (ALMA). A comparison of receiver noise temperature of the superconductor-insulator-superconductor mixers(SIS) mixer pumped by a Gunn oscillator LO and a photonic LO is demonstrated. Photonic LO system used for spectroscopic observation is conducted using Nobeyama 45-m telescope is analysed.