arXiv subjects

Jitendra Nath Acharyya

Publications and source records attributed to Jitendra Nath Acharyya.

3 recordsLinked to original sources

arXiv2021

Photonic and electronic state interactions in BaTiO3 based Optical Microcavity

The photonic modes mediated absorption dynamics at femtosecond time scales along with the control of spontaneous emission tunability are investigated all-dielectric optical microcavity having BaTiO3 (BTO) as defect layer. The cavity-enhanced transient absorption reveals the dominant excited state absorption (ESA) of both photonic and electronic modes due to strong third-order optical nonlinearity influence. Photoluminescence of BTO is found to be guided and tuned by the photonic cavity mode. Such active photonic structures can be envisaged as a potential candidate in nonlinear optics and photonic device applications.

physics.optics↗

arXiv2021

Recent advances in optics (RAO): Contribution of D Narayana Rao in optics and photonics research in India

The fist documented speculations on light were found in oriental and Greek schools of philosophy. The investigations on the light in India were rooted way back to the ancient era. The Indian Samkhya, Nyaya, and Vaisheshika identified light or fie (Tejas) as one of the key elements among the fie elementary things of the universe. The pioneering results of optics and spectroscopy were witnessed in the era of stellar people like Sir Jagadish Chandra Bose and Sir C V Raman. The research has then taken a new directive into the development of nonlinear optics and photonics after the invention of the laser. The present article reviews the past few decades pioneering works of Prof. D Narayana Rao, an experimental physicist, in the context of optics and photonics in India. The most notable contributions of Prof Rao, introduced in India for the fist time, are white-light interferometry, degenerate four-wave mixing (DFWM), electric field induced second harmonic generation (EFISHG), incoherent laser spectroscopy (using dye laser), and femtosecond lasers for creating nano/microstructures.

physics.optics↗

arXiv2021

Ultrafast nonlinear pulse propagation dynamics in metal-dielectric periodic photonic architectures

One-dimensional (1D) metal-dielectric (MD) periodic structures take advantage of large refractive index contrast between metal and dielectrics to invoke extremely high nonlinear ultrafast responses of metal. These structures are also special due to their extremely high laser damage threshold. The Bragg like 1D MD structure (Ag/SiO2)4 enables strong optical field confinement with much enhanced nonlinear features as compared to simple metal or single (Ag/SiO2)1 structure. In the present work, the ultrafast nonlinear optical responses of the above structures are investigated via femtosecond broadband optical pump-probe technique. The enhanced nonlinear optical absorption is of reverse saturation of absorption (RSA) nature, resulted due to free-carrier absorption (FCA) and excited-state absorption (ESA) processes. The spectral nonlinearities are closely related to the pump-induced modification of the metal's dielectric functions, which are qualitatively visualized by transfer matrix and two-temperature models. The ultrafast temporal evolution of nonlinear absorption clearly demonstrated enhanced optical nonlinearity, disentangled by the electron-electron and electron-phonon dynamic interactions at picosecond time scales. A phenomenological pulse propagation model is employed that incorporates the experimentally obtained nonlinear absorption coefficients and different nonlinear effects exhibited by the system. Nonlinearity plays a crucial role in controlling the ultrafast pulse propagation and could open a new window for many nonlinear device applications. The findings of these new optical materials could possibly pave the way for promising applications in ultrafast photonics.

physics.optics↗