Preliminary experiment for optical heterodyne communication with a single-mode optical fiber by using frequency-stabilized He-Ne lasers

Frequency fluctuation in a single-mode optical fiber is briefly discussed, and a preliminary experiment for optical heterodyne communication in a single-mode fiber is carried out with the aid of frequency-stabilized He-Ne lasers operating at a wavelength of 0.633 µm. As a result, we have obtained clear demodulated signals, having sinusoidal, triangular, and rectangular waveforms, through an optical fiber 100 m in length.