Photonics and Optoelectronics

9-14

Authors: K. Moovendaran, V. Jayaramakrishnan, S. Natarajan

Bulk-size single crystals of the nonlinear optical (NLO) materials: L-tartaric acid (LTA) and L-prolinium tartrate (LPT) were grown from aqueous solution using a home made crystal growth setup. Characterization of the crystals was investigated using single crystal X-ray diffraction. UV-vis-NIR spectra showed that the crystals have excellent transparency in the visible and infrared regions. Tentative assignments were made for the IR absorption peaks. The birefringence of the crystals was measured in the visible region and it was found to be varying with wavelength. Photoluminescence excitation studies showed that the emission occurred at 397 and 375 nm respectively, for LTA and LPT. The second harmonic generation (SHG) conversion efficiency of the powder samples of the crystals were measured as about 40% and 95% respectively, compared to that of the standard KDP crystals.

26-36

Authors: Partha Sona Maji, Partha Roy Chaudhuri

In this article, we’ve theoretically investigated the application of selective liquid infiltration towards realizing birefringent Photonic Crystal Fiber (PCF) and its operation in the single mode region. Birefringence has been created in a symmetrical structure PCF by infiltrating liquid of certain refractive indices in diagonally opposite air-holes. Different air-hole fraction along with different infiltrating refractive indices has been considered towards studying the effect of the parameters towards birefringence and loss. Cut-off properties for different infiltrating liquid has been performed and it has been found that PCF infiltrated with higher Refractive Indices (RI) liquid is suitable for broader range of single mode operation. The present structure provides very low loss and that can also be minimized with higher number of air-hole rings without affecting the birefringent property. Tunability property of the infiltrating liquid for various temperatures has been studied. By varying the refractive indices of the infiltrating liquid the birefringence can be well tuned. Our research will be useful in designing a birefringent PCF from conventional symmetrical PCF by infiltrating liquids in two diagonally opposite air-holes and proper choice of PCF parameter for single mode operation at a desired wavelength of interest.

51-58

Authors: Partha Sona Maji, Partha Roy Chaudhuri

We present a new design study of ultra-flat near zero dispersion PCF with selectively liquid infiltration with all uniform air-holes in the cladding towards achieving broadband supercontinuum generation (SCG). With rigorous series study of the optimization process we could achieve near zero ultra-flat dispersion as small as 0±0.41 ps/nm/km for broad wavelength range. The optimized near zero ultra-flat dispersion PCF has been targeted for smooth and flat broadband spectrum supercontinuum generation (SCG) for near Infrared (IR) applications. Broadband SC generations corresponding to three different designs of ultra-flat dispersion fiber have been carried out by using picoseconds pulse laser around the first zero dispersion wavelengths (ZDW). The numerical results show that FWHM of around 400 nm with less than a meter long fiber can be achieved with these fibers that cover most of the communication wavelength bands. The proposed design study will be applicable for applications in the field of tomography, Dense Wavelength Division Multiplexing (DWDM) system and spectroscopy applications etc.

66-69

Authors: Xiaowei Guo, Jia Liu, Shouqiang Zhang

The conversion efficiency of thin film silicon solar cell is still much below that of wafer silicon solar cell due to low optical absorption. Light trapping techniques can enhance the optical absorption in solar cells. Here, we design light trapping structures of double-side grating for ultrathin silicon solar cells based on a rigorous coupled-wave analysis method. The role of each grating was identified by analyzing the absorption spectra of ultrathin solar cell from 350 nm to 1100 nm wavelength at normal incidence, which shows use of top and bottom light trapping structures can achieve large optical absorption in different wave regimes. Inspired by this observation, the dual dielectric/dielectric and dielectric/ metallic grating structures were proposed and optimized to obtain broadband optical absorption close to the theoretic limit.