In an optically pumped semiconductor disc laser, which is always with a multiple layer active region and a large spot size, the spontaneous emission of quantum wells will be trapped by the waveguide caused by the multiple layer, travel a long excited distance relative to the surface-emitting mode and be subsequently amplified. Here we demonstrate a new mechanism for the amplified spontaneous emission (ASE): the etalon effect of the sub-cavity formed by the bottom distributed Bragg reflector and the top air–semiconductor interface. The spectral characteristics of this ASE including its temperature dependence, pump power dependence and observing angle dependence are experimentally studied, and the results are in good agreement with the theoretical model.
A high power and good beam quality InGaAs/GaAs quantum well semiconductor disk laser at 1 015 nm wavelength is reported. The semiconductor wafer is grown in reverse order: substrate is on the window side and the distributed Bragg reflector is the last grown epilayer. Then the wafer is up-side-down and capillary bonded to a SiC heatsink, and the substrate is chemically etched. Because the total thickness of the substrate-removed structure is less than 10 µm, the thermal management of the laser is significantly improved, and the maximum output power over 0.6 W is obtained using a 3% output coupler and 3.2 W incident pump power. The M 2 factors of 1.02 and 1.01 indicate a near-diffraction-limited beam quality. To further reveal the characteristics of this substrate-etched structure on the thermal management, the heat flux and the temperature distribution of the gain wafer are numerically analyzed, and the corresponding results are discussed.
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