Shallow-Tapered Chirped Fiber Bragg Grating Sensors for Dual Refractive Index and Temperature Sensing

In this work, we present a gold-coated shallow-tapered chirped fiber Bragg grating (stCFBG) for dual refractive index (RI) and temperature sensing. The stCFBG has been fabricated on a 15-mm long chirped FBG, by tapering a 7.29-mm region with a waist of 39 μm. The spectral analysis shows two distinct regions: a pre-taper region, in which the stCFBG is RI-independent and can be used to detect thermal changes, and a post-taper region, in which the reflectivity increases significantly when the RI increments. We estimate the RI and thermal sensitivities as 382.83 dB/RIU and 9.893 pm/°C, respectively. The cross-talk values are low (−1.54 × 10−3 dB/°C and 568.1 pm/RIU), which allows an almost ideal separation between RI and thermal characteristics. The stCFBG is a compact probe, suitable for long-term and temperature-compensated biosensing and detection of chemical analytes.

Design of optoelectronic oscillator based on multiple-length single mode fiber and chirped fiber Bragg grating

Wireless communication are becoming as a part of human life. If we want to achieve the efficient and affordable communication in wireless technology in optical domain, stable signal and ultra-low phase noise is required. Optoelectronic oscillator is based on converting continues light energy in stable and low phase noise, high-quality (Q) factor is used in wireless communication. If quality factor is low, then the oscillation dies out rapidly. Delay line is used provided higher-quality factor that is used. There are numerous techniques for the photonic generation of microwave signal with high time-bandwidth product and low phase noise. Optoelectronic oscillator (OEO) based generation techniques have been found one of the most interesting technique since last three decades. This approach provides very high frequency microwave signal with lowest possible phase noise. OEO has been designed with miscellaneous architecture by introducing different optical dispersive components such as optical fiber, chirped fiber Bragg grating, polarization modulator, and ring resonator. In this paper, numerous techniques for the design of OEO are reviewed and well demonstrated. There are interesting configurations with substantial improvement in phase noise and frequency of the microwave signals generated. MATLAB simulation has been used for the verification of result explained in this technique.