Simultaneous Measurements for Tunable Laser Source Linewidth with Homodyne Detection

The linewidth characteristics of a commercial tunable laser source (TLS) are measured experimentally employing self-homodyne detection method. Three linewidths are obtained at different operating wavelengths with two optical fiber delay lengths. It is found that a slightly higher values are obtained with a longer length of the delay fiber. The long of (50 km and 25 km) of single mode fiber SMF is enough to provide delay for the self-homodyne linewidth measurement