Research Work

Research output : Some of the key results are given here in detail.


Ultra Low Loss Fibers for Quantum Applications

Ultra low loss fiber designs are simulated for the application of single photon transmission in quantum communication. The chosen fiber designs are based on anti resonant hollow core fibers. The single and dual -nested anti resonant fibers (NARF) show the significant improvement in the confinement loss over the anti resonant fibers (ARF) The lowest loss value is obtained for dual nested fiber as of 10^-5 dB/km over the wavelength band of 600-700 nm. This fiber also shows the low dispersion near 650 nm. Due to low loss and low dispersion values, these fibers are useful in communication experiments.

Reference: Suchita, Sudip K. Chatterjee, Archana Kaushalram and Asha Bhardwaj, "Parametric study of anti-resonant fiber designs with nesting elements for ultra-low loss over visible band", Optical Fiber Technology, vol. 71, pp. 102910 1-10, 2022 https://www.sciencedirect.com/science/article/pii/S1068520022000931

Mode Dependent Characterization of Few Mode Fibers - Stimulated Brillouin scattering

A few mode fiber (FMF) shows mode dependent properties due to its two spatial optical modes - LP01 and LP11. We have studied intramodal and intermodal stimulated Brillouin scattering (SBS) using graded-index FMF. Simulation results show the selective combinations of both the fundamental and higher order optical-acoustic modes which give the significant Brillouin gain spectrum (BGS). BGS is sensitive to the refractive index change of the medium and hence, this study helps in understanding multi-parameter sensors.

Reference: Suchita, Balaji Srinivasan, Govind P. Agrawal and Deepa Venkitesh, “Role of the Modal Composition of Pump in the Multi-peak Brillouin Gain Spectrum in a Few-Mode Fiber”, Optics Communications, vol. 494, pp. 127052 1-7, 2021 https://doi.org/10.1016/j.optcom.2021.127052

Fiber based Mach-Zehnder Interferometer

Fiber-based Mach-Zehnder interferometer (MZI) is designed to test the spectral characteristics of various optical sources having different spectral widths (FWHM). The fixed-length MZI is useful to extract the spectral width of the input source which contributes to its coherence property.

Reference: Suchita and R. Vijaya, “Effect of source spectral width and its temporal coherence in the interference pattern of a Mach Zehnder interferometer,” Optics Communications, vol. 402, pp. 478–482, 2017 https://doi.org/10.1016/j.optcom.2017.06.063

Broadband Erbium-doped Fiber Lasers

A continuous wave, broadband erbium-doped fiber ring laser is designed using intracavity four wave mixing in presence of highly nonlinear fiber. Its spectral characteristics such as temporal coherence is characterized using Mach-Zehnder interferometer. This source finds its applicability in optical coherence tomography for low temporal coherence and the highly temporal coherent spectrally sliced narrow lines are suitable for coherent communication systems.

Reference: Suchita and R. Vijaya, “Temporal coherence of a low-power erbium-doped fiber laser with spectrally broadened output,” Journal of Optical Society of America A, vol. 34, no. 6, pp. 1004-1010, 2017,https://doi.org/10.1364/JOSAA.34.001004

Four Wave Mixing

Four wave mixing (FWM) is a third-order nonlinear optical effect occurs inside a nonlinear medium - highly nonlinear fiber. It is observed outside and inside a laser cavity. Its phase matching condition must be satisfied to get the high conversion efficiency. It plays an important role in deciding the temporally coherent output of a FWM-assisted laser cavity.

References: Suchita and R. Vijaya, “Temporal coherence study of four wave mixing products with and without the laser cavity effect,” Applied Optics, vol. 57, no. 5, pp. 1075–1082, 2018 https://doi.org/10.1364/AO.57.001075

Suchita, Soham Sarbadhikari, and R. Vijaya, “Spectral broadening due to intra-cavity four-wave mixing at low pump powers in erbium-doped fiber ring laser,” International Journal of Modern Physics B, vol. 28, no. 12, pp. 1442008 1-14, 2014 https://ui.adsabs.harvard.edu/link_gateway/2014IJMPB..2842008S/doi:10.1142/S0217979214420089

Stimulated Raman Scattering

Stimulated Raman scattering (SRS) is an inelastic scattering process having a higher threshold level which has been observed in solid, liquid and gaseous media. We have studied SRS in liquid toluene by exciting with a high power ns-pulsed laser source - NdYAG. Simultaneous measurement of all the Raman modes, including the second-order Stokes and first-order anti-Stokes are observed. All the vibrational modes of toluene are assigned to its observed peak.

Reference: Suchita Yadav, Govind Kumar, and R. Vijaya, “Spectral features of anti-Stokes and Stokes modes generated by stimulated Raman scattering in liquid toluene,” Applied Physics B, vol. 122, no. 10, pp. 257 1-10, 2016 https://link.springer.com/article/10.1007/s00340-016-6530-9