Laser linewidth measurements using self-homodyne detection with short delay

Optical Spectral Structure and Frequency Coherence

“…The disappearance of the -peak can be regarded as the criterion of coherence elimination and the lineshape broadening at the moment can be used as the optical linewidth. Up to date, lots of methods for analyzing lineshape and linewidth have been established in the past two decades (Chan, 2007;Dawson et al, 1992;Ludvigsen et al, 1998;Richter et al, 1986;Signoret et al, 2001;Signoret et al, 2004;Zhu et al, 2010). The method widely used for analyzing lineshape is delayed self-heterodyne technique.…”

Construction and Characterization of External Cavity Diode Lasers for Atomic Physics

“…If a laser is available with a known linewidth significantly smaller than that expected from the ECDL and it is within the tuning range of the ECDL, then that could be used instead. Another method commonly used for measuring linewidth is the delayed self homodyne technique 19,20 where part of the beam is sent along an optical delay line such as a fiber and then mixed on a beam splitter with the laser. This technique relies on the delay being longer than the coherence length of the laser under measurement.…”

Analysis of Self-Homodyne and Delayed Self-Heterodyne Detections for Tunable Laser Source Linewidth Measurements

“…The linewidth of a laser diode is typically in the megahertz region, but it can also be reduced to a few kilohertz, e.g. in external-cavity diode lasers, particularly with optical feedback from a high-finesse reference cavity [2]. Small fiber lasers in the form of distributed feedback lasers (with the resonator formed essentially by a special fiber Bragg grating) can generate tens of mill watts of output power with a linewidth in the region of a few kilohertz.…”