Prasad Saradh, AlHesseny Hanan Saleh, AlSalhi Mohamad S, Devaraj Durairaj, Masilamai Vadivel
Research Chair on laser diagnosis of cancers, College of Science, King Saud University, 11451, Riyadh, Saudi Arabia.
Department of Physics and Astronomy, College of Science, King Saud University, 11451, Riyadh, Saudi Arabia.
Nanomaterials (Basel). 2017 Jan 30;7(2):29. doi: 10.3390/nano7020029.
Tunable lasers are essential for medical, engineering and basic science research studies. Most conventional solid-state lasers are capable of producing a few million laser shots, but limited to specific wavelengths, which are bulky and very expensive. Dye lasers are continuously tunable, but exhibit very poor chemical stability. As new tunable, efficient lasers are always in demand, one such laser is designed with various sized CdSe/ZnS quantum dots. They were used as a colloid in tetrahydrofuran to produce a fluorescent broadband emission from 520 nm to 630 nm. The second (532 nm) and/or third harmonic (355 nm) of the Nd:YAG laser (10 ns, 10 Hz) were used together as the pump source. In this study, different sized quantum dots were independently optically pumped to produce amplified spontaneous emission (ASE) with 4 nm to 7 nm of full width at half-maximum (FWHM), when the pump power and focusing were carefully optimized. The beam was directional with a 7 mrad divergence. Subsequently, these quantum dots were combined together, and the solution was placed in a resonator cavity to obtain a laser with a spectral width of 1 nm and tunable from 510 to 630 nm, with a conversion efficiency of about 0.1%.
可调谐激光器对于医学、工程学和基础科学研究至关重要。大多数传统固态激光器能够产生数百万次激光脉冲，但限于特定波长，体积庞大且非常昂贵。染料激光器可连续调谐，但化学稳定性很差。由于一直需要新型可调谐、高效的激光器，一种这样的激光器采用了各种尺寸的CdSe/ZnS量子点进行设计。它们被用作四氢呋喃中的胶体，以产生520纳米至630纳米的荧光宽带发射。Nd:YAG激光器（10纳秒，10赫兹）的二次谐波（532纳米）和/或三次谐波（355纳米）一起用作泵浦源。在本研究中，当仔细优化泵浦功率和聚焦时，不同尺寸的量子点被独立光泵浦以产生半高全宽为4纳米至7纳米的放大自发辐射（ASE）。光束具有7毫弧度的发散角，呈定向性。随后，将这些量子点组合在一起，并将溶液置于谐振腔内，以获得光谱宽度为1纳米、可调谐范围为510至630纳米、转换效率约为0.1%的激光器。
