Direction Controlled Growth of Organic Single Crystals by Novel Growth Methods

Abstract

The green lasers are attractive and highly useful for lot of practical applications. It is more than fifty times brighter when compared to a red laser and thus it can be seen from miles away. Due to these features, the green lasers can be used in high-tech weapons for aiming purposes. More‐ over, the green lasers are highly useful for laser televisions and medical applications. Most of the commercially available green lasers are based on the diode pumped solid state frequencydoubled (DPSSFD) laser technology. For the past several decades, researchers and several in‐ dustries were trying to develop the laser diodes based on the compound semiconductors such as Gallium nitride (GaN) and Indium Gallium nitride (InGaN) especially in the blue and green region of wavelengths [1]. However, it is very difficult to grow bulk crystal of these materials with reasonable quality. Moreover, for the preparation of epitaxial thin films of these materi‐ als on substrates, highly sophisticated and expensive techniques like molecular beam epitaxy (MBE) and metal organic chemical vapour deposition (MOCVD) are needed. Apart from these growth aspects, the relatively low power and limited wavelength range restricts their use in important applications [2]. Therefore, laser sources based on Second harmonic generation (SHG) is a better choice for the applications which requires higher powers or longer wave‐ lengths (>400nm). As a consequence, the green laser technology still depends on the nonlinear optical phenomena such as frequency doubling.