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In the present study, we report the passive harmonic mode-locking (HML) of the external cavity tapered semiconductor laser system with saw-toothed microstructure. The stable picosecond pulse trains were observed up to the third order HML. The mechanism behind the system was analyzed and single-pulse energy of 59 pJ with a repetition rate of 412 MHz and pulse duration of 3.9 ps was realized.

A simple and effective approach based on the microstripe broad-area (MSBA) structure was proposed, and high-efficiency and high-power mid-infrared GaSb-based quantum well lasers were demonstrated. It was shown that the MSBA structure can effectively suppress the lateral current leakage and improve the temperature behavior of GaSb lasers. Compared with the conventional broad-area structure, the energy conversion efficiency of MSBA lasers was more than threefold and threshold current density decreased above 50%. High characteristic temperature and high beam quality were realized.

The high-power broad-area (BA) photonic bandgap crystal (PBC) diode laser is promising as a high-brightness laser source, however, it suffers from poor lateral beam quality owing to the intrinsic drawback of BA lasers. In this paper, a ladderlike groove structure (LLGS) was proposed to improve both the lateral beam quality and emission power of BA PBC lasers. An approximately 15.4% improvement in output power and 25.2% decrease in the lateral beam parameter product (BPP) were realized and the underlying mechanism was discussed. On the basis of the one-dimensional PBC epitaxial structure, a stable vertical far field was demonstrated.

High-power broad-area (BA) diode lasers often suffer from low beam quality, broad linewidth, and a widened slow-axis far field with increasing current. In this paper, a two-dimensional current-modulated structure is proposed and it is demonstrated that it can reduce not only the far-field sensitivity to the injection current but also the linewidth of the lasing spectra. Injection-insensitive lateral divergence was realized, and the beam parameter product (BPP) was improved by 36.5%. At the same time, the linewidth was decreased by about 45% without significant degradations of emission power and conversion efficiency.

One-dimensional photonic bandgap crystal (PBC) lasers have demonstrated ultra-low vertical divergence and record brightness; however, their future development is limited by their lateral beam quality. In this paper, a fishbone microstructure is proposed to control the lateral modes in broad-area PBC lasers. The findings reveal that the introduction of the microstructure improves the full width at half maximum of the lateral far field by 22.2% and increases the output power to a small extent. The detailed measurements show that the lateral beam parameter product decreases by 15.9%.