Ultra High Sensitive Refractive Index Sensor Using a Metal Under-Clad Ridge Waveguide Modal Interferometer Near the Dispersion Turning Point

Dwivedi, Ranjeet; Kumar, Arun; Tripathi, Saurabh Mani

doi:10.1109/jsen.2020.3035117

Cited by 10 publications

(4 citation statements)

References 25 publications

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“…The adlayer sensitivity is calculated by the ratio of the change in resonance wavelength (∆λ r ) to the change in the thickness of the adlayer (∆w ad ). This is expressed as [26],…”

Section: Affinity Sensingmentioning

confidence: 99%

“…Thus, similar to the case of bulk RI sensitivity, the incorporation of grating has a positive impact on affinity sensing as well. The RI of the adlayer is taken to be 1.45 as the RI of many of the protein and DNA layers [26,38] is distributed around it. When w ad ⩽ 20 nm, the λ r undergoes a profound shift in all of the situations depicted in figures 11 and 12.…”

Section: Affinity Sensingmentioning

confidence: 99%

“…The circular grating array delocalizes the core field into the sensing region to enhance field-matter interaction. The RI range of analytes (1.33-1.38 RIU) and adlayers (1.45 RIU) considered in our study corresponds to the biologically relevant analyte solutions and protein adlayers, respectively [26].…”

Section: Introductionmentioning

confidence: 99%

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Grating assisted temperature insensitive micro-ring resonator biosensor

Kumar Verma,

Kumari,

Mani Tripathi

2023

J. Opt.

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A grating-assisted temperature-insensitive micro-ring resonator bio-sensor is reported using finite-difference time domain simulation method. In addition to choosing a negative thermo-optic coefficient material water to nullify temperature-induced wavelength shift, optimization of the opto-geometric parameters provided a precisely zero-temperature sensitivity state of the structure. The negative thermo-optic coefficient of water counterbalances the positive shift in resonance wavelength originating from Si waveguides. The grating structure delocalizes the core field into the analyte region, which enhances field matter interaction to offer high bulk refractive index (RI) and affinity sensing. The advantage of incorporating grating structure in the ring has been demonstrated by comparing the bulk RI sensitivity and affinity sensitivity with and without the grating structure. Without the circular grating array, the bulk RI sensitivity is 214 nm/RIU and the affinity sensitivity is 0.139 nm/nm. Using grating in the ring structure offers an improved bulk RI sensitivity of 525 nm/RIU and an adlayer sensitivity of 0.515 nm/nm. We calculated the system limit of detection of the structure as ∼2×10−6 RIU. The fabrication tolerance of geometrical parameters, in the form of 10% variation in hole radius and 5% variation in other widths of our sensor, reveals a nominal temperature sensitivity of ∼6 pm/◦C. Changing the cladding analyte from pure water to other aqueous solutions, e.g. urine samples, also has a small impact on temperature sensitivity. The present work is useful in RI-dependent monitoring of the constituents present in aqueous medium-based bio-analytes samples in a variable ambient temperature environment.

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“…The adlayer sensitivity is calculated by the ratio of the change in resonance wavelength (∆λ r ) to the change in the thickness of the adlayer (∆w ad ). This is expressed as [26],…”

Section: Affinity Sensingmentioning

confidence: 99%

Section: Affinity Sensingmentioning

confidence: 99%

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Grating assisted temperature insensitive micro-ring resonator biosensor

Kumar Verma,

Kumari,

Mani Tripathi

2023

J. Opt.

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“…The common feature of all of these bimodal sensors is the fact that their sensitivity drastically increases inversely proportional to the group delay differences of the two modes, which takes part in the interaction. The conditions, when the group delay of two interaction optical waves is equal, are often called the "dispersion turning point" (DTP) [28,29] or "phase matching turning point" (PMTP) [30]. For the same optical length pass, the DTP condition is transformed to the case of the equal group indexes of two optical waves forming the filter part of the optical sensor.…”

Section: Introductionmentioning

confidence: 99%

Design of the Bimodal Grating Sensor with a Built-In Mode Demultiplexer

Tsarev

2023

Sensors

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This new sensor design provides good volume sensitivity (around 1600 nm/RIU) via collinear diffraction by the asymmetric grating placed in the waveguide vicinity. It provides the mode transformation between the fundamental TE0 and the first TE1 modes of the silicon wire (0.22 μm by a 0.580 μm cross-section) in the water environment. In order to provide the wavelength interrogation with a better extinction ratio for the measuring signal, the grating design is incorporated with the mode filter/demultiplexer. It selects, by the compact directional coupler (maximum 4 μm wide and 14 μm long), only the first guided mode (close to the cutoff) and transmits it with small excess loss (about −0.5 dB) to the fundamental TE0 mode of the neighboring single mode silicon wire, having variable curvature and width ranging from 0.26 μm to 0.45 μm. At the same time, the parasitic crosstalk of the input TE0 mode is below −42 dB, and that provides the option of simple and accurate wavelength sensor interrogation. The environment index is measured by the spectral peak position of the transmitted TE0 mode power in the output single mode silicon wire waveguide of the directional coupler. This type of optical sensor is of high sensitivity (iLOD~ 2.1 × 10−4 RIU for taking into account the water absorption at 1550 nm) and could be manufactured by modern technology and a single-step etching process.

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