Observation of optical gain in solutions of CdS quantum dots at room temperature in the blue region

Abstract

The optical gain dynamics has been studied for two CdS quantum dot samples dispersed in toluene at room temperature. This was carried out by using femtosecond transient absorption technique with an excitation at 400nm and gain measurement was studied at the fluorescence maxima (440 and 460nm). The optical gain lifetime was found to be as long as 20ps under pump fluence as low as 0.77mJ∕cm2. The low threshold is the result of long lifetime of electrons and holes and narrow emission bandwidth. These results suggest that CdS quantum dots in solution are excellent gain media for optically pumped high power blue lasers.

Blue Liquid Lasers from Solution of CdZnS/ZnS Ternary Alloy Quantum Dots with Quasi‐Continuous Pumping

“…[ 1,7 ] Extending the lasing wavelength down to the blue range requires further reduction of the dot size for stronger quantum confi nement, thereby rendering the higher nonradiative Auger recombination (AR) rate and more effi cient excited carriers trapping in small-sized blueemitting QDs. [ 1,7,8 ] Furthermore, most of the lasing demonstrations are limited in the form of solid fi lms by taking advantage of the available high packing-density exceeding the critical value predicted by Klimov et al [ 1,2,5,7,[9][10][11] Whilst, lasing from a liquid medium favors the development of high power lasers for the sake of the facilities of heat dissipation [ 12 ] and the development of optofl uidic lasers [ 13,14 ] which have great potential in biological research. However, only a limited number of studies have demonstrated lasing action from QDs in solution phase, [ 15,16 ] Adv.…”

Optical gain at 1550 nm from colloidal solution of Er^3+-Yb^3+ codoped NaYF_4 nanocubes

“…Among different type of NPs, semiconductors quantum dots (QDs) have been paid special attention because the quantum confinement effect provides them with exceptional optical properties, making them strong candidates for a variety of photonic applications, such as low-dimensional optical amplifier and laser medium. Up to the present, optical gain and laser actions in a wide spectrum range have been realized with metal chalcogenides QDs incorporated in planar waveguide structures and colloidal solutions [1][2][3]. However, due to their toxicity [4], and vulnerability under continuous pumping that may result in optical photo-degradation [5][6], application of QDs for commercial use still seems impractical at present.…”

Quantum dot containing nanocomposite thin films for photoluminescent solar concentrators

“…The resulting optical properties depend on the crystal size and can thus be tuned by varying the dimensions of the nanocrystals. Quantum dots are considered as promising candidates for optoelectronic applications including lightemitting diodes (Tasco et al, 2004) and quantum dot lasers (Darugar et al, 2006). Various concepts have been proposed for the use of nanostructured materials in solar energy conversion (Oelhafen and Schü ler, 2005).…”