| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical heterodyne detecting system which generates heterodyne signals of a high S/N ratio. SOLUTION: This optical heterodyne detecting system has attenuators (224; 324 and 424) each with an input for receiving an input signal (202; 302; 402) and an output for outputting an attenuated input signal, optical couplers (210; 310 and 410) each with a first input optically connected to the attenuator for receiving the attenuated input signal, a second input for receiving a local oscillator signal (206; 306; 406), and outputs for outputting coupled light signals including the input signal and the local oscillator signal, and photodetectors (212; 312 and 412), each with an input for receiving the coupled light signal from the optical coupler and an output for outputting an electrical signal describing the coupled light signal. |
