Free spectral range analysis of double series microresonator system for all-optical corrosion sensor

Abstract

A double series configuration of a microresonator is proposed to measure the amount of corrosion on iron metal. A numerical computation has been performed for analyzing the sensing operation in which the metal is attached to the waveguide as a top cladding material. The transparency peak profile and transfer function of the output transmission spectrum is obtained using a signal flow graph method and Mason's rule. The output spectrum of the microresonator shows that the linear free spectral range (FSR) changes as the iron begins to oxidize, which affects the cladding index of the sensing system. The FSR changes with respect to the amount of corrosion present in iron metal. In addition, the microresonator is able to distinguish two different types of corrosion, which are hematite and magnetite. The ▻ Authors ▻ Keywords Brought to you by INTERNATIONAL ISLAMIC UNIVERSITY MALAYSIA Search Sources Lists ↗ SciVal Create account Sign in References (39) Author keywords all-optical corrosion sensor double-series microresonator refractive index Indexed keywords Engineering controlled terms: Cladding (coating) Hematite Iron Magnetite Metal analysis Refractive index Resonators Signal flow graphs Engineering uncontrolled terms All optical Corrosion sensor Double series Free spectral range Micro resonators Numerical computations Output transmission Types of corrosions Engineering main heading: Corrosion Funding details

Integrating Vernier spectrum with Fano resonance for high sensitivity of an all-optical sensor

“…In the spectrum, there are several noticeable Fano-like line-shape, and asymmetrical resonances as shown in Fig. 2 at the 1.538 to 1.540 µm double peak [28]. Special features of Fano resonance is the sharp dip [34] with local maximum and minimum as shown in Fig.…”

“…The light intensity builds-up due to the resonance effect as it travels within the circulation path of the ring waveguide. The resonance light inside the microring waveguide experiences an optical phase shift [28] as 𝜉 and 𝜉 1,2 for all-pass racetrack and double racetrack configuration, respectively. Constructive interference occurs as the resonance light is in phase with the incoming light in the bus waveguide.…”

“…The effective refractive index is calculated based on the Marcatilli's approach. Unlike [30,31] that modelled the refractive index for non-linear material, the simpler method was used in this study, which is finding the effective index based on the cross-sectional waveguide for linear materials such in [28,32]. There are three materials within the cross-section which are the core (Si), the substrate (SiO2), and the cladding, air.…”

“…Table 1 shows the configuration parameters involved and their optical transfer function equations. The single-pass amplitude a = exp(−𝛼𝐿 𝑅 /2) and exp(𝑖𝑘𝑛𝐿 𝑅 ) represents the optical phase shift of all-pass racetrack microring resonator where 𝐿 𝑅 is the optical path length of the system [28,33]. For double racetrack configuration, the optical phase shift is defined as…”

“…In Equation ( 6) and ( 7), there are self-coupling coefficient, 𝑡, 𝑐 1,2 = √ 1 − 𝜅 1,2 √ 1 − 𝛾 1,2 [25] and cross-coupling coefficient, 𝑠 1,2 = √ 𝜅 1,2 √ 1 − 𝛾 1,2 [28], where 𝜅 is coupling coefficient [28] and 𝛾 is loss coefficient [28]. The normalized intensity was computed by squaring the optical transfer function and plotting it against the wavelength domain.…”