The laterally coupled DFB-LD shows unique advantages to achieve single longitudinal mode LD, which has attracted the attention of researchers both at home and abroad in recent years. The laterally coupled DFB-LD can not only effectively solve wavelength stability problem of a LD, but also can realize high performance devices owing to its easy preparation technology. It is of great importance to the development of small, efficient and low-cost wavelength locked semiconductor lasers. In this paper, we analyzed laterally coupled DFB-LD in terms of its structural characteristics, operating mechanism, and output characteristics. As the grating position is different from that of the traditional Bragg grating, different fabrication means are explored and compared. Therefore, its progress over the world is reviewed, and its wide applications are forecasted.
A novel vertical-cavity surface-emitting laser (VCSEL) with single mode, high-power, low divergence, and temperature stability is presented. The most prominent structural feature of the device is that the high optical loss region is formed by an anti-phase surface relief above the top Distributed Bragg Reflectors (DBRs) and the light-emitting aperture is ringshaped with larger region. The simulation results show the device with 15μm oxide aperture and 5μm width ring light emitting region achieves stable single-higher-order transverse mode emission with a side mode suppression ratio (SMSR) of more than 80dB. The maximum continuous-wave (CW) single mode power is up to 15.2 mW and far-field divergence angle (FWHM) is lower than 4.5°. Moreover, the VCSEL maintains CW single mode emission up to a record high temperature of 450K.
A large size vertical-cavity surface-emitting laser (VCSEL) with multiple concentric ring apertures (MCRA) is investigated. Compared with a typical VCSEL with the same outer dimension, the 804nm VCSEL with MCRA has maximal continuous wave(CW) light output power 0.23 W which is about 3 times that of a typical device. The novel laser also exhibits a stable single-lobed far field pattern with low beam divergence angle, which is suitable for free-space optical communication and optical interconnection applications.