Injection laser characteristics due to reflected optical power

Fluctuations in injection laser output intensity and spectrum caused by light reflected from an optical system are investigated theoretically and experimentally. The theoretical analysis is accomplished by applying the semiclassical theory to an injection laser, and introducing an optical feedback term. It is shown that light reflected from a near-field region causes power deviation and an oscillating wavelength shift. It is also shown that reflected light from a far-field region changes laser light spectrum and introduces frequency noise components in laser output power.