Wavelength trimming of distributed-feedback lasers by photo-absorption-induced disordering

We have proposed the use of photo-absorption-induced disordering for post-fabrication adjustment of lasing wavelength (wavelength trimming), and demonstrated 0.36 nm trimming in a 1.55 μm ridge waveguide DFB laser. The technique utilizes the band gap dependent absorption of the incident laser photons in quantum well (QW) layers, which generates heat and induces intermixing ofthe QW. The active region consisted of five compressively-strained 1.55 μm InGaAsP quaternary quantum wells with the separate confinement heterostructure (SCH). The PAID method is particularly useful for multiple-wavelength DFB laser arrays for wavelength-division-multiplexed systems where every wavelength must be aligned with predefined channels