Near Diffraction Limited High Power Tapered Semiconductor Lasers

High power high beam quality semiconductor laser are finding more and more applications, such as diode pumping solid state lasers, fiber optical communication system, material processing and medicine. Tapered semiconductor lasers can obtain high power and near diffraction beam quality output, so it gains more and more attention nowadays. At first, the theoretical model of tapered semiconductor laser is stated in the dissertation, and theoretical analysis of tapered semiconductor laser is carried out by employing beam propagation method (BPM), the output power, near field and far field of the device are calculated under various conditions. On the base of numerical analysis, the influence of epitaxial structure to beam quality is analyzed, and the device configuration of tapered semiconductor laser is designed. After that, the tapered semiconductor laser is fabricated, and the device properties are tested, the parameters of device are stated as follows: threshold current is 900mA, slope efficiency is 0.75W/A, wall plug efficiency is 30%, horizontal divergence angle is 3.9, vertical divergence angle is 40. Experimental results indicate that the tapered semiconductor laser has good beam quality.At last, the measurement and calculation principles of M~2 factor are stated. The near-field and far-field measurement installing is established, and the M~2 factor of the tapered semiconductor laser is measured, its minimum value is 1.1, meanwhile, the highest continuous output power of the device is 4.5W and more than 2.5W continuous output power of the tapered semiconductor laser which has near diffraction limited beam quality is obtained, when the value of M~2 factor is 1.3. Therefore, Experimental results indicate that tapered semiconductor laser is desirable as sources for high beam quality, high output power.