scholarly journals Phenomenon of Electromagnetic Field Resonance in Metal and Dielectric Gratings and Its Possible Practical Applications

2020 ◽  
Vol 5 (3) ◽  
pp. 49
Author(s):  
Stefano Bellucci ◽  
Andrii Bendziak ◽  
Oleksandr Vernyhor ◽  
Volodymyr M. Fitio
Keyword(s):  
Refractive Index ◽  
Buffer Layer ◽  
Propagation Constant ◽  
Refractive Index Change ◽  
Dielectric Substrate ◽  
Angular Sensitivity ◽  
Practical Applications ◽  
Dielectric Gratings ◽  
Constant Change ◽  
Dielectric Grating

Calculations of the field distribution in the structure of the dielectric substrate/buffer layer/volume phase grating/analyzed medium were performed. It is shown that in the presence of a buffer layer with a low refractive index in the dielectric waveguide leads to a shift of the maximum field at the waveguide resonance into analyzed medium. As a result, the spectral and angular sensitivity of the corresponding sensor increases. Based on the waveguide equation, analytical expressions are obtained that connect the spectral and angular sensitivity of the sensor to the sensitivity of the propagation constant change due to the refractive index change of the analyzed medium. The conditions for the excitation of the resonance of surface plasmon–polariton waves in the structure with a metal or dielectric grating on a metal substrate are also given. The fields that occur at resonance for silver and gold gratings are calculated.

Junction temperature measurement in optically-activated power MOSFET

2022 ◽  
Author(s):  
Sandro Rao ◽  
Elisa D Mallemace ◽  
Maurizio Casalino ◽  
Giuseppe Cocorullo ◽  
Lakhdar Dehimi ◽  
...  
Keyword(s):  
Refractive Index ◽  
Refractive Index Change ◽  
Optical Power ◽  
Junction Temperature ◽  
Essential Information ◽  
Power Mosfet ◽  
Practical Applications ◽  
Power Operations ◽  
Fabry Perot ◽  
Periodic Monitoring

Abstract The temperature-dependent optical properties of silicon carbide (SiC), such as refractive index and reflectivity, have been used for a direct monitoring of the junction temperature of a power MOSFET. In particular, the optical response of a 4H-SiC MOSFET-integrated Fabry-Perot cavity to temperature changes has been investigated through parametric optical simulations at the wavelength of λ=450 nm. The reflected optical power exhibited oscillatory patterns caused by the multiple beam interference for which the MOSFET epilayer, between the gate-oxide and the doped 4H-SiC substrate, acts as a Fabry-Perot etalon. These results were used to calculate the refractive index change and, therefore, the optical phase shift of ∆φ= π/2 corresponding to a temperature variation that can be considered as a warning for the device “health”. In practical applications, the periodic monitoring of the optic spectrum at the interferometric structure output gives an essential information about the device operating temperature condition that, for high power operations, may lead to device damages or system failure.

scholarly journals High-Sensitive TM Modes in Photonic Crystal Nanobeam Cavity with Horizontal Air Gap for Refractive Index Sensing

2019 ◽  
Vol 9 (5) ◽  
pp. 967 ◽  
Author(s):  
Jin-Kyu Yang ◽  
Chae-Young Kim ◽  
Minji Lee
Keyword(s):  
Refractive Index ◽  
Photonic Crystal ◽  
Refractive Index Change ◽  
Air Gap ◽  
Q Factor ◽  
Practical Applications ◽  
Refractive Index Sensing ◽  
Tm Mode ◽  
Cavity Structure ◽  
New Type

We propose a new type of refractive index sensing based on the transverse magnetic (TM) modes in the photonic crystal (PhC) nanobeam (NB) cavity with a horizontal air gap. The electric field of the resonant TM mode is strongly confined within the horizontal air gap present at the PhC NB cavity. In order to increase the quality (Q) factor and the sensitivity (S) of the refractive index change in the air simultaneously, the cavity structure is fully optimized. Because of the trade-off between the Q-factor and S of the TM mode in the PhC NB cavity with an air gap, there is an optimal thickness of the air gap in the dielectric slot. From the numerical simulation results, S can exceed 1000 nm/RIU with Q > 40,000. When the dielectric slot becomes thin, S could be higher than 1200 nm/RIU. For practical applications, we suggest an Si-based PhC NB cavity with a horizontal SiO2 slot structure which can also provide high S with a high Q-factor after a very fine selective wet etching process. This new type of TM resonant mode in the PhC NB cavity can be an ideal platform for compact sensors in photonic integrated circuits for TM waveguide systems.

scholarly journals Critical angle reflection imaging for quantification of molecular interactions on glass surface

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guangzhong Ma ◽  
Runli Liang ◽  
Zijian Wan ◽  
Shaopeng Wang
Keyword(s):  
Refractive Index ◽  
Small Molecule ◽  
Molecular Interactions ◽  
Glass Surface ◽  
Critical Angle ◽  
Dynamic Range ◽  
Refractive Index Change ◽  
Label Free ◽  
Index Change ◽  
Sensing Range

AbstractQuantification of molecular interactions on a surface is typically achieved via label-free techniques such as surface plasmon resonance (SPR). The sensitivity of SPR originates from the characteristic that the SPR angle is sensitive to the surface refractive index change. Analogously, in another interfacial optical phenomenon, total internal reflection, the critical angle is also refractive index dependent. Therefore, surface refractive index change can also be quantified by measuring the reflectivity near the critical angle. Based on this concept, we develop a method called critical angle reflection (CAR) imaging to quantify molecular interactions on glass surface. CAR imaging can be performed on SPR imaging setups. Through a side-by-side comparison, we show that CAR is capable of most molecular interaction measurements that SPR performs, including proteins, nucleic acids and cell-based detections. In addition, we show that CAR can detect small molecule bindings and intracellular signals beyond SPR sensing range. CAR exhibits several distinct characteristics, including tunable sensitivity and dynamic range, deeper vertical sensing range, fluorescence compatibility, broader wavelength and polarization of light selection, and glass surface chemistry. We anticipate CAR can expand SPR′s capability in small molecule detection, whole cell-based detection, simultaneous fluorescence imaging, and broader conjugation chemistry.

Simplified coupling power model for fibers fusion

2009 ◽  
Vol 17 (3) ◽  
Author(s):  
J. Saktioto ◽  
J. Ali ◽  
M. Fadhali
Keyword(s):  
Refractive Index ◽  
Propagation Constant ◽  
Tunable Filter ◽  
Experimental Result ◽  
Total Power ◽  
Optical Parameters ◽  
Coupling Region ◽  
Ratio Distribution ◽  
Hydrogen Flow ◽  
Wide Range

AbstractFiber coupler fabrication used for an optical waveguide requires lossless power for an optimal application. The previous research coupled fibers were successfully fabricated by injecting hydrogen flow at 1 bar and fused slightly by unstable torch flame in the range of 800–1350°C. Optical parameters may vary significantly over wide range physical properties. Coupling coefficient and refractive index are estimated from the experimental result of the coupling ratio distribution from 1% to 75%. The change of geometrical fiber affects the normalized frequency V even for single mode fibers. V is derived and some parametric variations are performed on the left and right hand side of the coupling region. A partial power is modelled and derived using V, normalized lateral phase constant u, and normalized lateral attenuation constant, w through the second kind of modified Bessel function of the l order, which obeys the normal mode and normalized propagation constant b. Total power is maintained constant in order to comply with the energy conservation law. The power is integrated through V, u, and w over the pulling length of 7500 µm for 1-D. The core radius of a fiber significantly affects V and power partially at coupling region rather than wavelength and refractive index of core and cladding. This model has power phenomena in transmission and reflection for an optical switch and tunable filter.

InP-based optical switch module operating through carrier-induced refractive index change

1990 ◽  
Vol 29 (3) ◽  
pp. 191 ◽  
Author(s):  
Takeshi Kato ◽  
Hiroaki Inoue ◽  
Yasushi Takahashi ◽  
Koji K. Ishida
Keyword(s):  
Refractive Index ◽  
Optical Switch ◽  
Refractive Index Change ◽  
Index Change ◽  
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