New Method for Homodyne Laser Linewidth Measurements with a Short Delay Fiber

摘要

A new versatile method for homodyne laser line width measurements is presented. The acousto-optic modulator used in the standard self-heterodyne technique is replaced by electronic upconversion. This results in reduced optical loss and a simpler setup. The dependence of the detected homodyne signal on the mean phase difference between the mixed beams was averaged out with a phase modulator on the delay fiber. A delay fiber shorter than the coherence length of the laser can then be used.