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In this work, a polarization-independent waveguide based on magnetic photonic crystal (MPC) with a triangular lattice of air holes in Yttrium Iron Garnet (YIG) slab grown on alumina (Al2O3) substrate is proposed, where both TE-like and TM-like periodic band gaps overlap. YIG is well known for its attracting magneto-optical (MO) properties and used to produce a coupling between the TE and TM modes. Thus, a nonreciprocal effect can be obtained by applying an external magnetic field parallel to the direction of propagation. At 1550 nm, the complete photonic band gap is simulated and optimized using the three dimensional plane-wave expansion method. The aim of this study is to enhance Faraday rotation (FR) while maintaining a low modal birefringence. A numerical analysis in function of magnetic gyration (g) has been reported, using the BeamProp software. The results reveal a proportional relation between FR, Δn and g, such for g = 0.5, a large FR of 26.11×104 °/cm with Δn = 7×10−6. The results show a real improvement of this MPC structure based on YIG with larger FR, lower modal birefringence and minimal losses. The notable enhancement in the MO behaviour could improve the performance of optical isolators, and makes it suitable for nonreciprocal devices.

We present numerical study of microcavity biosensor in photonic crystal (PC) with triangular lattice of air holes patterned perpendicularly to an InP-based confining heterostructure. The microcavity is formed by varying the radius of one air hole. The 2D finite difference time domain (FDTD) method algorithm (fullwave simulator) is used to compute the light transmission efficiency and the quality factor (Q) when the refractive index (RI) filled in the air holes of water and polymer. The detected spectrum has a Lorentzian line shape, and the peak occurs when the PC cavity is at resonance. The resonance wavelength of this cavity will shift accordingly due to the variation of RI. The polymer filling of photonic crystal holes can be used to measure gas, fluids, biolayers, or bound chemical.

In this work, we propose a slab waveguide structure based on a magneto-photonic crystal, formed by a triangular lattice of circular air holes in a cerium-substituted yttrium iron garnet (Ce-YIG) medium grown on a silica (SiO ) substrate; in this structure, we have studied the width of the photonic band gap (PBG) using the expansion plane waves method in three dimensions to reach and optimize the complete PBG, centered at the telecommunication wavelength, also a theoretical study of the conversion mode, reported and studied the effect of some parameters such as the radius and the thickness using a beam propagation method in two dimensions. In our proposed structure, the maximum conversion modes ratio equal to 98% with a low coupling length LC = 15 µm is obtained for gyrotropy  = 0.36 and Faraday rotation FR = 1500 × 104 deg/cm.

Based on numerical simulations, we propose a new type of magnetic sensor based on a two-dimensional (2D) photonic-crystal nanocavity infiltrated by a magnetic fluid and a broadband W1 waveguide. The defect length and the diameter of the holes surrounding the L4 nanocavity are optimized, yielding a structure with a quality factor of 8655.8. Magnetic fluids with different magnetic nanoparticle volume fraction concentrations and various refractive indices are infiltrated into special holes. Magnetic field sensing is realized based on the change in the refractive index of the magnetic fluid with the external magnetic field strength, resulting in a shift of the resonant wavelength. The magnetic field sensitivity and full-width at half-maximum increase with the number of infiltrated air holes. A refractive index sensitivity of 146.97 nm/refractive index unit (RIU) is obtained for the structure with 12 infiltrated air holes, with an optimum figure of merit indicating the good performance of this magnetic field sensor structure. These distinguished features and the excellent tunable refractive index property of the magnetic fluid make the designed device suitable for application in magnetic field sensing.

In this work, we propose a new filter design based on a ring resonator. This structure has 99% transmission ratio and high sensitivity to detect small refractive index variations of the order of 0.002. More specifically, the small size of this resonator gives the advantage to model a demultiplexer of size 463 µm based on four ports which operates in the conventional transmission band. Also, we show that our demultiplexer structure can reach more than 90% transmission ratio with an optical quality factor of about 3800, the spectral width is 0.72 nm and a crosstalk between −13.28 and −32.13. In our study, we emphasized the plane wave method to study the photonic band gap and FDTD to determine the transmission spectrum.

This paper presents the design and analysis of a temperature sensor that utilizes an optical filter consisting of an elliptical-shaped photonic crystal ring resonator (E-PhCRR) in a two-dimensional configuration. The basic structure comprises silicon (Si) rods immersed in the air (disconnected structure) arranged in a triangular lattice. The newly designed structure’s photonic band gap (PBG) was calculated using the plane wave expansion (PWE) method, and the temperature sensor was modeled and studied using the finite difference time domain (FDTD). The temperature change causes a redshift in the resonance wavelength due to the subsequent change in refractive index. The temperature was systematically adjusted within the range of 0 °C to 50 °C, leading to a discernible change in the resonant wavelength by 5.2 nm, shifting it from 1682.59 nm to 1687.79 nm. The elliptical shape of the photonic crystal ring resonator provided us with significant flexibility to attain improved outcomes. Specifically, we achieved a quality factor of 316200, a temperature sensitivity of 103.92 pm/°C, and a refractive index sensitivity of 443 nm/RIU. Furthermore, we were able to acquire a detection limit of 5.12 × 10 - 9 RIU while maintaining a compact size of 116.5 μ m 2 .

We theoretically investigate a high sensitive photonic crystal integrated biosensor array structure which is potentially used for label-free multiplexed sensing. The proposed device consists of an array of three sandwiched H0 cavities patterned above silicon on insulator (SOI) substrate; each cavity has been designed for different cavity spacing and different resonant wavelength. Results obtained by performing finite-difference time-domain (FDTD) simulations, indicate that the response of each detection unit shifts independently in terms of refractive index variations. The optimized design makes possible the combination of sensing as a function of location, as well as a function of time in the same platform. A refractive index sensitivity of 520nm/RIU and a quality factor over 104 are both achieved with an accompanied crosstalk of less than -26 dB. In addition, the device presents an improved detection limit (DL) of 1.24.10-6 RIU and a wide measurement range. These features make the designed device a promising element for performing label-free multiplexed detection in monolithic substrate for medical diagnostics and environmental monitoring.

A kind of magnetic field sensor (MFS) using a two-dimensional (2D) magnetic photonic crystal (MPC) slab waveguide as the sensing structure is proposed and investigated numerically. The slab structure is based on bismuth iron garnet (BIG), a well-known magnetic material with effective magnetooptical (MO) properties, sandwiched with gadolinium gallium garnet (GGG) as substrate. The complete photonic bandgap (PBG) of the 2D MPC is simulated and optimized for realization of polarization-independent waveguides. The simulation results show that the width and position of the complete PBG depend on the thickness of the BIG slab and the radius of the air holes used in the design. By reducing the lightwave propagation losses and enhancing the mode conversion ratio, increased sensitivity is obtained. Based on the Faraday effect, a good linear relationship is observed between the normalized output light intensity and the magnetic field strength as the gyrotropy parameter g is varied from 0.13 to 0.19, a g -range used as the sensor dynamic range. The remarkable enhancement in sensing performance due to the MO effect makes the designed device suitable for magnetic field sensing. The results are discussed to provide a basis for investigation of 2D MPC slab waveguides based on the same structure, which are of particular interest for development of highly sensitive MFSs.

In this work, we are interested in the design of a basic filter structure based on an annular ring cavity where we study its characteristics and its performance in terms of transmission and selectivity of the signal. The basic structure is a 2D photonic crystal (PC) with holes in the substrate which are more suitable for different PC manufacturing processes. Based on the optimization of the filter structure results, we created a high performance structure and improved a 4 channels demultiplexer (DEMUX) with an optical parameters which are the transmission efficiency, the quality factor and the crosstalk with average values of 97.25, 3171 and −26.58 dB, respectively, it had a significant role in optical communication networks. The compact size of the proposed DEMUX is 211.7 μm which is suitable for the integrated optics. To determine the photonic band gap (PBG) of our proposed structure, we used the plane wave expansion (PWE) method and the finite difference time domain (FDTD) method used to study normalized transmission.