Anisotropic Semiconductor Crystals for Terahertz Frequencies

Terahertz (THz) technology shows great promise for threat detection and imaging of concealed weapons, explosives, mail and packaging materials, chemical and biological agents, luggage at airport security checkpoints, and medical diagnostics. THz frequencies however have not been fully and successfully utilized because of a lack of compact high power sources and high efficiency detectors. To address these needs, EIC Laboratories proposes to grow large-area, defect free ultrapure nonlinear optical (NLO) crystals for generating and detecting THz radiation in the 0.3 ¡V20 THz range (10-600 cm-1). The crystal is a unique layered anisotropic binary semiconductor with great potential for terahertz frequency generation. Its broad transmission range with low absorption coefficient (<1 cm-1) and large nonlinear coefficient (d22 „d 75 pm/V) enables phase matching accessible over a broad THz range. In the Phase I research, commercially available precursor materials will be purified using zone refining, and then large single crystals will be grown using a modified Bridgman technique. Physical, opto-electronic, and spectroscopic properties of the grown crystals will be characterized repetitively to achieve optimum crystal growth conditions. The performance evaluation and high potential of this material as a tunable THz source and sensor will be demonstrated.