Studies on optically induced nonlinear absorption and refractive index of Br1 crystal for near IR optical switching application

•Br1 compound was synthesized and crystallized for optoelectronic application.•NLRI (10−11 m2/W) of Br1 crystal was calculated by using Z-scan.•Two figures of merit have been calculated W=47>1 and T=0.12<1.•Laser damage threshold of Br1 crystal is 1.1388 GW/cm2.•Response time of Br1 crystal is in micro seconds.

A newly synthesized 2-{3-[2-(4-bromophenyl) vinyl]-5, 5-dimethylcyclo-hex-2-en-1-ylidene} malononitrile (Br1) organic compound has been studied. Br1 crystals were grown by employing the solution growth method. The single crystal XRD analysis shows that Br1 crystallizes in the monoclinic space group P21/c, with cell parameters a=10.064(5), b=11.218, c=14.862 and V=1667.2. TG and DTA studies show Br1 melts at 195.1 °C and decomposes at 352 °C. UV absorption spectrum of Br1 crystal shows the cutoff wavelength at 614 nm, and the wide transparency of crystal is in the region of 615–1550 nm. The optical constants are theoretically calculated in the optical communication range 1300–1550 nm. The refractive index of Br1 crystal (1.655) has been measured using Abbe's refractometer. Z-scan technique with He–Ne laser has measured the optical nonlinearity of Br1 crystal along the a, b and c axes. The mechanism of the nonlinear variation of crystal can be regarded as the thermal nonlinear effects. The largest third order nonlinear refractive index is along the c-axis, possessing a value of 11.6194×10−6 esu which is larger than that of the a and b axes. Photoinduced absorption is responsible for the optical absorption of the organic molecular crystal. The two figures of merit, W=47>1 and T=0.12<1 are suitable for optical switching application. Photoluminescence spectrum of crystal has been studied using xenon lamp in the wavelength range of 450–700 nm. The sharp emission of photoluminescence spectrum is excited at 642.74 nm (137711 a.u). Laser damage threshold of Br1 crystal has been studied using Nd-YAG laser. The laser energy is initiating the crack at 89.4 mJ after 10 s on the surface (100) of Br1 crystal.