A low-cost optofluidic platform for the colorimetric assessment of bacterial activity in domestic wastewater.

Optofluidic chips represent a cost-effective platform for the development of miniaturized devices to perform biochemical reactions at a microscale. The dye reduction-based electron-transfer activity monitoring (DREAM) assay is a colorimetric approach that has been adopted for the rapid assessment of bacterial activity in bioreactors used in bioremediation and industrial biotechnology. A three-layered PMMA-based optofluidic chip having laser-machined microchannels coupled with a detection system comprising an LED source and a photodiode interfaced with a microcontroller for automation constituted the experimental setup.

Harmonic mode-locked noise-like pulses under a Q-switched envelope in an erbium doped all-fiber ring laser.

We report for the first time, to the best of our knowledge, harmonic mode-locked noise-like pulses under a -switched envelope in an all-fiber erbium doped ring laser cavity, mode locked using the nonlinear polarization rotation (NPR) technique. For a cavity with a fundamental repetition rate of 1.33 MHz, stable mode-locked noise-like pulses, with few nanoseconds durations, single pulse energies around 30-40 nJ, and -switched repetition rates up to 31 kHz, were produced and characterized from the fundamental to the eighth harmonic.

Active loss compensation in the resonant optical gyroscope with a "reflector": towards a cost-effective alternative for the navigational grade.

The performance of passive fiber optic gyroscopes involving ring resonators is limited mainly by the loss and finesse of the cavity. In this work, we show performance enhancement of the recently studied resonant fiber optic gyroscope with a "reflector" using active loss compensation. Our gyroscope does not require expensive ultra-narrow linewidth lasers, expensive lock-in detection methods, or polarization-maintaining fibers, which are mandatory for all standard resonant fiber optic gyroscopes.

Self-beating resonant optical gyroscope with a "reflector": the possibility of high sensitivities at reduced costs.

Using simulations and theoretical analysis, we present an innovative readout technique that uses the change in a beat frequency signal for sensing rotation in the resonant fiber gyroscope with a "reflector." Unlike traditional fiber optic gyros, this gyroscope uses an embedded reflecting element that deliberately couples the clockwise and counter-clockwise propagating waves for sensing rotation. Our analytical results predict increased immunity to the degrading effects of backscattering, Kerr nonlinearities, and ambient variations at an optimum nonreciprocal bias.

Novel optical gyroscope: proof of principle demonstration and future scope.

We report the first proof-of-principle demonstration of the resonant optical gyroscope with reflector that we have recently proposed. The device is very different from traditional optical gyroscopes since it uses the inherent coupling between the clockwise and counterclockwise propagating waves to sense the rotation. Our demonstration confirms our theoretical analysis and simulations.

Coupled-cavity analysis of the resonant loop mirror: closed-form expressions and simulations for enhanced performance lasing.

A coupled-cavity analysis of the resonant loop mirror with a signal flow graph technique is presented. Use of this technique has resulted in simple closed-form expressions for reflectance, transmittance, critical coupling, bandwidth, finesse, gain threshold, and mode splitting. Application of this device to enhance the single longitudinal mode operation of a fiber laser is also proposed.