LINEAR AND NONLINEAR OPTICAL PROPERTIES OF 2,7-DINITRO-9-FLUORENONE SINGLE CRYSTAL

The linear and nonlinear optical properties of 2,7-dinitro-9-fluorenone single crystals are investigated, especially those affecting the usage for optical second-harmonic generation. Sufficient optical quality plate-like crystals have been grown by sublimation in purified nitrogen flow. The crystal is transparent in the visible and near-infrared region, is negative biaxial with n(a) > n(c) > n(b) and has birefringence with n(a) - n(b) = 0.52 at 532 nm. The nonlinear optical coefficients determined by Maker fringe method are d(33) = 8pm / V and d(32) = d(24) = 0.4 pm/V. Type I and type II critical phase matching are possible in the near infrared region and type I is preferable.