Tunable Laser Diode Using Partially Intermixed InGaAsP Multiple Quantum Well

In this work, a two-section wavelength tunable laser diode is demonstrated using an InGaAsP multiple quantum well heterostructure. The laser diode consists of two sections with different bandgap energies achieved using selective area intermixing of the MQW. Using plasma enhanced chemical vapor deposition (PECVD), half of the sample is coated with a 30nm silicon nitride (SiNx) film followed by a 200nm thick overlay of silicon oxynitride (SiOxNy) film over the entire sample. The whole sample is then thermally annealed at 750 degrees C for 30s, and that results in the SiOxNy covered section experiencing a narrowing of the bandgap energy, while leaving the SiNx covered section practically unchanged. A laser stripe is fabricated that passes through both MQW sections. The wavelength of laser operation can then be tuned by varying the injected current levels applied separately to the two sections. The obtained tuning range was 40 nm spanning from 1538 nm to 1578 nm.