A Novel Design of Quarter Wave-shifted Distributed Feedback Semiconductor Laser for High-power Single-mode Operation

The spatial hole burning effect has been known to limit the performance of distributed feedback semiconductor diode lasers. As the biasing current of a single quarterly-wavelength-shifted distributed feedback diode laser increase, the gain margin reduces. Therefore, the maximum single-mode output power of the quarterly-wavelength-shifted distributed feedback diode laser is restricted to a relatively low power operation. The spatial hole burning phenomenon caused by the intense electric field leads to a local carrier depletion at the centre of the cavity. Such a change in carrier distribution alters the refractive index along the laser cavity an ultimately affects the lasing characteristics. In order to ensure a large gain margin ∆αL between the lasing mode and the most probable side, and also a uniform internal field distribution, subsequently a stable single longitudinal mode operation, distributed feedback lasers structures with modifications in the corrugation will be considered. Namely, the inclusion of phase-shifts and non-uniform coupling coefficients is presented with a comparative analysis of the laser performances in the abovethreshold regime