A compact and ultra high sensitive RI sensor using modal interference in an integrated optic waveguide with metal under-cladding

Cost-Effective Mach-Zehnder Interferometer Liquid Refractive Index Sensor Based on Conventional Polymer Strip Waveguide

“…Table 2. For the sensors using the novel waveguides to enhance sensitivity [10][11][12][13][14][15], the MZI sensor with silicon nitride slot waveguide achieved the sensitivity of 2633π/cm RIU [11], while the other MZI sensors in [10, 12 -15] exhibit the sensitivity lower than that achieved in this work. For the sensors based on engineering the OPD of used MZI to enhance sensitivity [16,18], the sensitivity of our proposed MZI sensor is much larger than that of the MZI sensor based on vernier effect in [18], but slightly inferior to the MZI sensor based on dip splitting effect in [16].…”

“…Over the past decades, optical waveguide liquid refractive index (RI) sensors have received more and more attention as an increasingly important tool in biochemical analysis applications by virtue of their unique advantage enabling high-sensitive, real-time, and label-free detection [1]. To date, various optical waveguide liquid RI sensors employing various configurations, including ring resonator [2][3][4], grating-assisted directional coupler [5], grating [6], Young interferometer [7], multimode interferometer [8], and Mach-Zehnder interferometer (MZI) [9][10][11][12][13][14][15][16][17][18], have been proposed. Among them, the MZI-based sensors have distinctive advantages of structural simplicity and diversity, design flexibility, and the potential of ultra-high sensitivity, making them an important and promising type.…”

“…As the MZI-based sensors also utilize evanescent field probing scheme, to enhance light-analyte interactions and hence to achieve large waveguide sensitivity, strong penetration of the evanescent field into the analyte is required. To this end, some novel waveguides, including plasmonic waveguide [10], slot waveguide [11], hybrid plasmonic waveguide [12,13], subwavelength grating slot waveguide [14], and the waveguide with metal under-cladding [15], have been proposed and evaluated during the past years. And they actually help the improvement of the waveguide sensitivity.…”

Highly Sensitive Refractive Index Sensor Based on Polymer Bragg Grating: A Case Study on Extracellular Vesicles Detection

“…The high interacting field leads to a high sensitivity. Over the years, various photonic structures have been proposed such as surface Plasmon polaritons (SPPs) [ 17 , 18 ], 2D materials [ 19 , 20 ], long period gratings (LPGs) [ 21 , 22 ], multimode interferences [ 23 ], ring resonators [ 24 , 25 ], Bragg gratings [ 26 , 27 , 28 , 29 , 30 , 31 ], etc. The performance of the structures based on LPGs, SPPs, multimode interferometers, and ring resonators is often limited by broad bandwidth, a bulky setup, or a free spectral range.…”

A Compact, Highly Sensitive pH Sensor Based on Polymer Waveguide Bragg Grating

“…In this context, an integrated optical waveguide geometry can be an elegant solution as it provides larger freedom in choosing geometry as well as materials [21]. In the last few years, it has been reported that the evanescent field of an integrated optical waveguide can be enhanced significantly to the surrounding medium by incorporating a metal layer underneath the waveguide core [22][23][24]. Recently, it has been noticed that the evanescent field can be further improved by considering high-index nanocoating on top of a ridge waveguide [25].…”