A Highly Versatile Porous Core Photonic Quasicrystal Fiber Based Refractive Index Terahertz Sensor

Miniaturized real-time fiber optic sensing systems with high sensing performance are in extreme demand. In this work, we propose a novel photonic quasicrystal fiber sensor in the terahertz region and test its sensing characteristics using the finite element method. The proposed simulated sensor numerically investigates the cancer-infected cells from the normal cells in the human cervix, blood, adrenal glands, and breast based on the difference in their refractive index changes. The effective refractive index of core-guided mode is due to the interaction of light between the refractive index of the fiber material and infiltrated normal and cancer cells, respectively. The proposed sensor exhibits a high birefringence of 0.03, a low dispersion of 0.35 ps/THz/cm, along with a high numerical aperture of 0.99. Besides, the sensor holds a less-effective material loss of 2.53 × 10-9 (dB/cm), a maximum power fraction of 88.10, a maximum relative sensitivity of 82.67%, and an effective mode area of 3.16 mm2. The results envisage that the proposed sensor displays high sensing performances with a rapid cancer detection mechanism.

Highly sensitive refractive index sensor based on plastic optical fiber balloon structure

A novel, to the best of our knowledge, design of plastic optical fiber (POF) balloon-based refractive index sensor for the detection of different concentrations of sodium chloride is proposed and experimentally investigated. The experimental characterization supports the finding that the transmission loss is sensitive to the external environment's targeted refractive index changes of the analyte. The proposed sensor achieves a maximum intensity-based sensitivity of 3105 RIU^-1, resolution of 3.22 ×10^-7, and the figure of merit (FOM) is 326 RIU^-1 from 2 to 2.5 Mol/L of the analyte with the chosen refractive index changes at 680 nm for a diameter D = 0.1 cm of the POF balloon structure. Furthermore, a high linear performance of 0.9896 is achieved with good robustness against the fabrication imperfection. The ultra-sensitiveness to the refractive index with a simple demonstration of the POF balloon-based structure has potential applications in the chemical, biological, and food safety sensing fields.

Ultrasensitive temperature sensor with Vernier-effect improved fiber Michelson interferometer

A novel fiber Michelson interferometer (FMI) based on parallel dual polarization maintaining fiber Sagnac interferometers (PMF-SIs) is proposed and experimentally demonstrated for temperature sensing. The free spectral range (FSR) difference of dual PMF-SIs determines the FSR of envelope and sensitivity of the sensor. The temperature sensitivity of parallel dual PMF-SIs is greatly enhanced by the Vernier effect. Experimental results show that the temperature sensitivity of the proposed sensor is improved from -1.646 nm/°C (single PMF-SI) to 78.984 nm/°C (parallel dual PMF-SIs), with a magnification factor of 47.99, and the temperature resolution is improved from ±0.03037°C to ±0.00063°C by optimizing the FSR difference between the two PMF-SIs. Our proposed ultrasensitive temperature sensor is with easy fabrication, low cost and simple configuration which can be implemented for various real applications that need high precision temperature measurement.

Effects of two weak continuous-wave triggers on picosecond pulse pumped supercontinuum generation

The promising advancement of supercontinuum generation in optical fibers has initiated significant interest in recent research studies and several continuing applications. We numerically corroborate the effects of picosecond pulse pumped supercontinuum (SC) by using two weak continuous-wave (CW) triggers with 1% pump intensity. Compared with SC with one CW trigger, adding two CW triggers (1% pump power), both near the modulation instability peaks, can achieve wider spectra for a picosecond pulse pumped SC. Furthermore, good coherence properties may be achieved in the wavelength range from 1300-2000 nm when one CW trigger is near the pump center wavelength and the other CW trigger is distant from the pump. In our simulations, putting two CW triggers on the same side (concerning the pump wavelength) or putting them on different sides have similar effects on SC spectral and temporal coherence properties. Therefore, by engineering the wavelengths of two CW triggers to offer better bandwidth or coherence, we envision that the proposed technique could play a significant role in the generation of SC.