Browsing by Subject "Dual wavelength"
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Item Open Access All-fiber, single-mode spectral beam combining of high power Tm-doped fiber lasers(OSA, 2015) Yılmaz, S.; Ottenhues, C.; Wysmolek, M.; Theeg, T.; Lamrini, S.; Scholle, K.; Fuhrberg, P.; Sayınç, H.; İlday, Fatih Ömer; Neumann, J.; Overmeyer, L.; Kracht, D.Signal beam combining of Tm-doped fiber lasers can increase the laser output power while simultaneously maintaining the single mode beam quality. We demonstrate an all-fiber integrated dual-wavelength Tm-doped fiber laser with an output power of 36 W by using the spectral beam combining method. The constituent lasers are operating at the wavelengths 1949 and 1996 nm and an in-house-made WDM is used for combination of these two different wavelengths. All-fiber truly single mode power combining is demonstrated for the first time in this wavelength region.Item Open Access Enhanced hole transport in InGaN/GaN multiple quantum well light-emitting diodes with a p-type doped quantum barrier(Optical Society of America, 2013) Ji Y.; Zhang, Z. -H.; Tan S.T.; Ju, Z. G.; Kyaw, Z.; Hasanov N.; Liu W.; Sun X. W.; Demir, Hilmi VolkanWe study hole transport behavior of InGaN/GaN light-emitting diodes with the dual wavelength emission method. It is found that at low injection levels, light emission is mainly from quantum wells near p-GaN, indicating that hole transport depth is limited in the active region. Emission from deeper wells only occurs under high current injection. However, with Mg-doped quantum barriers, holes penetrate deeper within the active region even under low injection, increasing the radiative recombination. Moreover, the improved hole transport leads to reduced forward voltage and enhanced light generation. This is also verified by numerical analysis of hole distribution and energy band structure. © 2013 Optical Society of America.