Potassium second harmonic generation

Leigh D A, Moody A E, Wade F A, King T A, West D and Bahra G S 1995 Second harmonic generation from Langmuir-Blodgett films of fullerene-aza-crown ethers and their potassium ion complexes Langmuir 11 2334-6... 

Only certain types of crystalline materials can exhibit second harmonic generation (61). Because of symmetry considerations, the coefficient must be identically equal to zero in any material having a center of symmetry. Thus the only candidates for second harmonic generation are materials that lack a center of symmetry. Some common materials which are used in nonlinear optics include barium sodium niobate [12323-03-4] Ba2NaNb O lithium niobate [12031 -63-9] LiNbO potassium titanyl phosphate [12690-20-9], KTiOPO beta-barium borate [13701 -59-2], p-BaB204 and lithium triborate... 

Indeed, it exhibits SHG (second harmonic generation) activity that is three times higher than that of commercially relevant NLO (nonlinear optical active) materials such as potassium dihydrogenphosphate. 

Potassium Dihydrogen Phosphate. KDP crystals are used for second-harmonic generation of laser radiation. 

Potassium titanyl phosphate, K TiO PO4 (KTP), is a much favoured material for use in optoelectronics. It is widely used for second harmonic generation of Nd lasers emitting near 1 mm, and is a superior material for many optical waveguide applications. 

Potassium niobate is mainly used in optics (Bhalla et al. 2000) as today s best material for second harmonic generation. 

Pulsed lasers such as Nd YAG and excimer lasers are commonly used for the pump-probe experiment just mentioned. Some characteristics of these lasers are listed in Table 3-1. Although the fundamental of the Nd YAG laser is at 1,064 nm, this frequency can be multiplied by using nonlinear crystals, such as KDP (potassium dideuterium phosphate), to obtain the second (532 nm), third (355 nm) and fourth (266 nm) harmonics. Furthermore, a wide range of UV-visible pulsed radiation can be generated from th se harmonics by pumping a dye laser or using a Raman shifter (Sectior 2.2.5). 

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