Simulation of enhanced plasma effect wavelength tunable lasers

The enhanced plasma effect (EPE) laser is a novel tunable multiquantum well (MQW) distributed feedback (DFB) laser with a thick reservoir layer between p-cladding and MQW layers. Performance of the EPE laser has been simulated by LDSCOPE (laser diode simulator by self-consistent opto-electronic model). Fast wave length shift due to the plasma effect is enhanced by increased carrier density change in the reservoir owing to the carrier transport effect. The calculated threshold and FM efficiency are in good accordance with those obtained experimentally. Calculated results suggest that a tuning range over 2.5 nm due to the plasma effect would have been obtained in the fabricated EPE laser with a 0.6 μm reservoir for the bias current range below 300 mA if it had not been for leakage current. A reservoir thicker than the diffusion length does not lead to a wider tuning range, because of carrier recombination in the reservoir. A thin barrier layer inserted between the reservoir and the MQW layer, however, will improve the carrier distribution in the reservoir, so that the tuning range may be expanded by 20%