High-sensitivity integrated SiN rib-waveguide long period grating refractometer

Abstract

In this research, we demonstrate a high-sensitivity integrated silicon nitride long period grating (LPG) refractometer based on a rib waveguide with sinusoidally modulated width. While integrated LPG architectures typically achieve ultrahigh sensitivity only over a narrow optical bandwidth using a phase-matching turning-point optimization technique, our sensor exhibits a very high refractometric sensitivity that was designed to remain constant over a broad operational optical spectral bandwidth. The proposed design method relies on multi-modal dispersion tailoring that consists of homogenizing the spectral behaviors of both group and effective indices of the coupling modes. Experimental results are in agreement with numerical simulations, demonstrating not only a sensitivity reaching 11,500 nm/RIU but, more significantly, also that this sensitivity remains almost constant over a broad spectral range of at least 100 nm around 1550 nm. Additional advantages of the proposed sensor architecture encompass a low temperature sensitivity, down to −0.15 nm/K, and simplicity of the fabrication process. These results demonstrate the feasibility of chip-scale photonic integration to achieve both high sensitivity and large dynamic range of the proposed refractometer.

Gas Sensor Based on Silicon Nitride Integrated Long Period Grating

“…This architecture achieves a sensitivity of 6.8 fm/ppm of CO 2 which corroborates with the PHMB RI sensitivity. As a result, in the future, LPG with higher sensitivity such as the one described in [16] can be used to achieve even higher sensitivity close to 32 fm/ppm. This type of design thus appears promising and can benefit from improvements or hybridations, potentially involving new sensing mechanisms, like plasmonics or photonic crystals.…”

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

“…A long-period grating with a sinusoidally modulated width of a silicon nitride rib waveguide was already demonstrated in the high-sensitivity bimodal sensor [34]. The interaction between the fundamental and the sixth mode provideda sensitivity reaching 11.5 μm/RIU, but more significant is that this sensitivity remained almost constant over a wide spectral range of at least 100 nm to around 1550 nm [34]. It is not typical of bimodal sensors having variable sensitivity to increase with the approaching optical wavelength up to the dispersion turning point.…”

Manipulation of Photonic Jets of Topological Gratings Comprising ITO Strips and Nanowalls Using Refractive Indices of Dielectric Nanofilms

“…Optical gratings including phase gratings, binary gratings, surface relief gratings, Bragg gratings, and plasmonic gratings have many fascinating and groundbreaking applications, such as wave couplers for photonic circuits, [1][2][3][4] beam steering for imaging, [5][6][7][8] signal interconnection for communication, [9][10][11][12] holographic data DOI: 10.1002/lpor.202300659 storage for information processing, [13][14][15][16] and sensing for dielectric materials. [17][18][19][20] These applications rely on large diffraction angles, high efficiencies, and strong electromagnetic resonance of optical gratings. The large diffraction angles of optical gratings can be achieved by reducing their periods via semiconductor processes or deflecting their diffracted beams by integrating them with optical elements.…”