Mode-selective optical sensing using asymmetric waveguide junctions

Abstract

a b s t r a c tMeasuring a single analyte in a highly absorptive microfluidic channel has always been a challenge. Even with a highly selective sensing layer, other chemical species can affect the interrogation of the analyte. Matching the evanescent tail with the sensing layer thickness is difficult in case of evanescent field sensing. The tail typically extends beyond the sensing layer, introducing noise and spurious errors in the measurement, which scales up with analyte concentration. In this work therefore, we propose the use of a simple multimode evanescent waveguide sensor that eliminates such common spurious effects. The proposed mode-selective sensing system exploits the sensitivity differences between the different guided modes in detecting the effects of the outer medium in the sensor response. The operation of the sensor device relies on the use of an asymmetric waveguide junction, which enable efficient separation of waveguide modes and therefore detection of their differences in behaviour. The proposed device is shown through simulations to achieve very small estimation errors below 5%, even for very high absorption coefficients of the outer medium of up to 80 times larger than that of the sensing layer.

Lithographically Fabricated Magnifying Maxwell Fisheye Lenses

“…Compact and efficient mode sorters are required in on-chip mode-division multiplexing [7] and sensing [8] applications. COMSOL Multiphysics simulations of a Maxwell fisheye-based mode sorter are presented in Figure 6, where the signal is sent in through a multimode waveguide from the left and out-coupled through three single mode output waveguides to the right.…”

Optimization of a New GaN-Based Blue Laser Diode with a Quadruple Asymmetric Waveguide for High Efficiency Performance

“…Several suggestions have been offered for waveguide engineering to increase the laser diode output power [4]. Eventually, the employment of an asymmetric waveguide layer would be a way to balance the carrier confinement and high output power in LD design [5]- [8]. Single-mode waveguide structures using asymmetric waveguide structures are of great interest because of their unique features.…”