arXiv subjects

Garima Bawa

Publications and source records attributed to Garima Bawa.

3 recordsLinked to original sources

arXiv2020

Simultaneous existence of ultra-high and ultra-low spectral sensitivity for Directional Couplers

We present the experimental evidence for the existence of two exciting wavelengths, termed critical and cross-over wavelength in the transmission spectrum of fiber-optic directional coupler, whose properties are conjugate to each other. The spectral shift associated with the transmission maxima/minima suddenly flip around these wavelengths and the spectrum shows largest (nil) spectral shift for the transmission maxima/minima closest to the critical ( at the cross-over) wavelength, corresponding to the same perturbation parameter. A theoretical explanation of the observed experimental behavior has also been presented, highlighting that the underlying mechanisms for the existence of these wavelengths are entirely different. The knowledge of the precise spectral location of these wavelengths is necessary to avoid false alarms.

physics.optics↗

arXiv2018

Single-Multi-Single Fibre Optic Structure Based Water Depth Sensor

We propose and demonstrate a technique easy to fabricate and measure water depth based on selective mode excitation using single-multi-single (SMS) mode structure. The high extinction ratio has been achieved by equally exciting preselected modes of the multi-mode fibre (MMF) by optimizing the core offset at both the input/output splices of the SMS structure, and a wavelength shifting has been achieved by varying the ratio of major to minor axis of the MMF loop. A theoretical analysis of the observed behaviour is also presented showing an excellent agreement between the theoretical and experimental results.

physics.app-ph↗

arXiv2018

Critical Wavelength in the Transmission Spectrum of a Directional Coupler Employing GeO 2 -doped Single Mode Fibers

We examined the existence of critical wavelength in transmission-spectrum of a Directional Coupler, employing GeO 2 - doped SMF and showed that it differs significantly from that observed in SMS structures. The origin of critical wavelength is explained. The sensitivity has been observed to be maximum for the transmission maximum or minimum nearest to the critical wavelength. The existence of a wavelength below the critical wavelength called the cross-over wavelength where the spectrum again changes its nature of spectral shift has also been observed. The effect of increase of core radius and of seperations between cores of the two fibers; and the change in GeO 2 doping concentration inside core on critical wavelength has also been studied. It was observed that there exist two critical wavelengths for a Directional Coupler consisting of a fiber having B 2 O 3 doping along with GeO 2 while the other has only GeO 2 doping. The effect of temperature and strain on the transmission spectrum of the Directional Coupler has been studied.

physics.optics↗