High power tapered lasers with nearly diffraction-limited beam quality have attracted much attention in numerous applications such as nonlinear frequency conversion, optical pumping of solid-state and fiber lasers, medical treatment and others. However, the large vertical divergence of conventional tapered lasers is a disadvantage, which makes beam shaping difficult and expensive in applications. Diode lasers with photonic crystal structure can achieve a large mode size and a narrow vertical divergence. In this paper, we present tapered lasers with photonic crystal structure emitting at 980 nm. The epitaxial layer is grown using metal organic chemical vapor deposition. The device has a total cavity length of 2 mm, which consists of a 400-um long ridge-waveguide section and a 1600-um long tapered section. The taper angle is 4°. An output power of 3.3 W is achieved with a peak conversion efficiency of 35% in pulsed mode. The threshold current is 240 mA and the slope efficiency is 0.78 W/A. In continuous wave mode, the output power is 2.87 W, which is limited by a suddenly failure resulting from catastrophic optical mirror damage. The far field divergences with full width at half maximum are 12.3° in the vertical direction and 2.9° in the lateral direction at 0.5 A. At high injection level the vertical divergence doesn’t exceed 16°. Beam quality factor M2 is measured based on second moment definition in CW mode. High beam quality is demonstrated by M2 value of less than 2 in both vertical and lateral directions.
We report the first demonstration of blue shift of optical pumping photonic crystal (PhC) laser. A femtosecond laser was
used to pump the InGaAsP based two dimensional photonic crystal laser at room temperature. Linear dependence of the
resonance wavelength with respect to the pump power is observed: dλ/dP=-1.5×10-2 nm/μW . Blue shift of overall
1.1nm was obtained with the increase power of pump laser. These results are in agreement with theoretical expectation
while the carrier-induced index change is introduced into the PhC semiconductor laser. It shows a possibility that by
proper wafer design and careful optimization, we may obtain wavelength stable photonic crystal laser, which is
important in photonic integration.