A comprehensive design optimization of 1.55- m high power In GaAsP/In P board area lasers is performed aiming at increasing the internal quantum efficiency (ηi) while maintaining the low internal loss (αi) of the device, thereby achieving high power operation. Four different waveguide structures of broad area lasers were fabricated and characterized in depth. Through theoretical analysis and experiment verifications, we show that laser structures with stepped waveguide and thin upper separate confinement layer will result in high áiand overall slope efficiency. A continuous wave (CW) single side output power of 160 m W was obtained for an uncoated laser with a 50-μm active area width and 1 mm cavity length.
We report a direct, modulated bandwidth enhancement in a amplified feedback laser(AFL), both experimentally and numerically. By means of fabricated devices, an enhanced-3 d B bandwidth of 27 GHz with an in-band flatness of 3 d B is experimentally confirmed at 13 °C. It is numerically confirmed that the modulated bandwidth of the AFL can be enhanced to two times its original bandwidth, with more controlled flexibility to realize a flat, small-signal response.
Internal loss is a key internal parameter for high power 1060-nm In Ga As/Al Ga As semiconductor laser.In this paper,we discuss the origin of internal loss of 1060-nm In Ga As/Ga As quantum well(QW) Al Ga As separate confinement heterostructure semiconductor laser,and the method to reduce internal loss.By light doping the n-cladding layer,and stepwise doping the p-cladding layer combined with the expanded waveguide layer,a broad area laser with internal loss of 1/cm is designed and fabricated.Ridge waveguide laser with an output power of 350 m W is obtained.The threshold current and slope efficiency near the threshold current are 20 m A and 0.8 W/A,respectively.
A 1.3-μm 1 4 MMI coupler is designed and fabricated on an InP substrate based on a shallow etched waveguide structure. Tapered input/output waveguides and a bending waveguide design are adopted and applied in the device to optimize the performance. The average excess losses of the 1 4 MMI coupler per channel are 2.8,1.7,2.9,and 2.9 dB,respectively. The smallest excess loss can be lower than 0.5 dB in the 40-nm spectrum bandwidth. The average uniformity between the four channels of the MMI coupler is 1.3 dB,while the smallest uniformity is only 0.4 dB.
