Fig. 1. (Color online) Illustration of (a) the band structure of the four-QW coupling and two-phonon resonance-based QC structure, and (b) the corresponding layered cross-sectional structure of the QC material.

Fig. 2. (Color online) (a) Schematic diagram of the double-trench narrow ridge waveguide structure of SLE devices. (b) Corresponding scanning electron microscope image of the straight end. The top-view microscope images of SLE devices with (c) 8°- or (d) 12°-inclined TW.

Fig. 3. (Color online) Schematic drawings (left) and optical field simulations (right) of the SLEs with (a) α = 0°, (b) α = 8°, or (c) α = 12°, respectively.

Fig. 4. (Color online) Emission characteristics of SLEs measured under quasi-CW (15 kHz, 2 μs) mode at 80 K: (a) L–I curve of the SLE with α = 8°, and the inset is the corresponding lasing spectrum at 780 mA; (b) L–I curve and (c) emission spectra of the coated SLE.

Fig. 5. (Color online) (a) L–I curve and (b) emission spectra of SLEs with α = 12° measured under quasi-CW (15 kHz, 2 μs) regime at 80 K.