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 na>nc>nb and has birefringence with na−nb=0.52 at 532 nm. The nonlinear optical coefficients determined by Maker fringe method are d33=8 pm/V and d32=d24=0.4 pm/V. Type I and type II critical phase matching are possible in the near infrared region and type I is preferable.