Fullerenes are the third allotrope of carbon and have received much attention due to their unique properties. In this monograph on 'Optical Gain and Relaxation Mechanism of Fullerenes in Solutions', the effect of concentration of Fullerenes C60 and C70 molecules on their fluorescence spectra are studied in detail. Moreover, Forster's Resonance Energy Transfer (FRET) from different dyes to the fullerenes are investigated and it has been found that Fullerene C60 -Coumarin C440 pair and also Fullerene C70 - Quinizarine pair may be used as spectroscopic rulers. Time Resolved Spectra of both the fullerenes in pure as well as in mixture form were measured and the results show that the optical gain is concentration-dependent and only Fullerene C70 shows positive gain, which can be used as a lasing material.

Laser-induced effects on cadmium selenide thin films with different compositions of cadmium and selenium and also the thin films of cadmium sulfide are investigated using nitrogen laser and Nd: YAG laser of second harmonic generation. The thin films are prepared by using vacuum thermal evaporation technique. Structural, optical, FTIR and photo-conductivity measurements on the thin films are carried out and the effects of laser irradiation on such properties are studied. It has been found that laser irradiation may lead to formation of nano-materials of the chalcogenide thin films

Bulk GaP is an indirect-gap (2.26 eV) semiconductor and is a poor light emitter. Therefore, the crystalline size reduction in the formation of porous GaP is the crucial step towards opto- electronic device applications. Porous GaP based structures possess high luminescence efficiency across the wide range from green-blue to UV spectrum. The laser-induced etching process has the added advantage of a control of size and optical properties without needing the use of electrodes. The laser-induced etching process is a promising technique for fabricating many optoelectronic devices including: light emitter devices, detectors, sensors and large-scale integrated circuits. The surface phonon frequency depends on the nanocrystalline size, shape and dielectric constant of the surrounding medium.The average crystallite size was estimated to be 3nm. The broadening of Raman line is caused by the size distribution, which is dependent on the etching parameters.