Broadband terahertz absorption and Q-switching behavior of 5-chloro-2-nitroaniline (5C2NA) crystals

The growth of transparent 5-chloro-2-nitroaniline (5C2NA) crystals was achieved using the slow evaporation solution technique in this paper. The X-ray diffraction and Fourier transform-infrared spectroscopy analysis confirmed the crystal structure and molecular fingerprints of 5C2NA, respectively. UV–Vis and photoluminescence (PL) spectroscopy were employed to investigate the material’s band gap and ground state absorption, respectively. The thermogravimetric analysis indicates that the stability of the grown crystals was achieved at up to 211 °C. Dielectric measurements and Urbach plots suggest the presence of fewer defects in 5C2NA crystals. Terahertz time-domain spectroscopy was utilized to observe the variation of absorption coefficient and refractive index in the terahertz frequency regime. Nonlinear optical effects, such as saturable absorption (SA) and reverse saturable absorption (RSA), are pivotal in the development of all-optical logic gates. The transition between SA and RSA are crucial in optoelectronic applications. In this study, we investigate the 5C2NA crystal, revealing its ability to exhibit both SA and RSA under the Z -scan technique with varying pump intensities. Switching properties observed in 5C2NA can be harnessed for applications such as all-optical logic gates, rapid optical switching, optical limiting, mode storage, among others.