Frequency stabilization of millimeter-wave subcarrier using laser heterodyne source and optical delay line

A frequency stabilization technique for laser heterodyne sources that is applicable to fiber-radio systems is experimentally demonstrated, It employs an optical delay line as a frequency reference instead of a millimeter-wave oscillator. A subcarrier signal with a 12.3-MHz deviation was generated in a 10-GHz band by using commercial-grade DFB-LDs.