Gaussian beam diffraction by two-dimensional refractive index modulation for high diffraction efficiency and large deflection angle

The refractive index modulation associated with the implantation of oxygen or silicon into waveguides formed in silicon-on-insulator (SOI) has been investigated to determine the feasibility of producing planar, implantation induced Bragg grating optical filters. A two-dimensional coupled mode theory-based simulation suggests that relatively short grating lengths, on the order of a thousand microns, can exhibit sufficient wavelength suppression, of >10 dB, using the implantation technique. Fabricated planar implanted slab-guided SOI waveguides demonstrated an extinction of −10 dB for TE modes and −6 dB for TM modes for the case of oxygen implantation. Extinctions of −5 dB and −2 dB have been demonstrated with silicon implantation.

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Dynamic two-dimensional refractive index modulation for high performance acousto-optic deflector

Optics Express ◽

10.1364/oe.23.033667 ◽

2015 ◽

Vol 23 (26) ◽

pp. 33667 ◽

Cited By ~ 3

Author(s):

Tiansi Wang ◽

Chong Zhang ◽

Aleksandar Aleksov ◽

Islam A. Salama ◽

Aravinda Kar

Keyword(s):

Refractive Index ◽

High Performance ◽

Refractive Index Modulation ◽

Two Dimensional ◽

Index Modulation

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Diffraction of a Gaussian Beam with Limited cross Section by a Volume Phase Grating under Waveguide Mode Resonance

Materials ◽

10.3390/ma14092252 ◽

2021 ◽

Vol 14 (9) ◽

pp. 2252

Author(s):

Volodymyr Fitio ◽

Iryna Yaremchuk ◽

Andriy Bendziak ◽

Michal Marchewka ◽

Yaroslav Bobitski

Keyword(s):

Refractive Index ◽

Fourier Transform ◽

Plane Wave ◽

Gaussian Beam ◽

Waveguide Mode ◽

Plane Waves ◽

Refractive Index Modulation ◽

Phase Grating ◽

Transmitted Waves ◽

Index Modulation

In this work, the diffraction of a Gaussian beam on a volume phase grating was researched theoretically and numerically. The proposed method is based on rigorous coupled-wave analysis (RCWA) and Fourier transform. The Gaussian beam is decomposed into plane waves using the Fourier transform. The number of plane waves is determined using the sampling theorem. The complex reflected and transmitted amplitudes are calculated for each RCWA plane wave. The distribution of the fields along the grating for the reflected and transmitted waves is determined using inverse Fourier transform. The powers of the reflected and transmitted waves are determined based on these distributions. Our method shows that the energy conservation law is satisfied for the phase grating. That is, the power of the incident Gaussian beam is equal to the sum of the powers of the reflected and transmitted beams. It is demonstration of our approach correctness. The numerous studies have shown that the spatial shapes of the reflected and transmitted beams differ from the Gaussian beam under resonance. In additional, the waveguide mode appears also in the grating. The spatial forms of the reflected and transmitted beams are Gaussian in the absence of resonance. It was found that the width of the resonance curves is wider for the Gaussian beam than for the plane wave. However, the spectral and angular sensitivities are the same as for the plane wave. The resonant wavelengths are slightly different for the plane wave and the Gaussian beam. Numerical calculations for four refractive index modulation coefficients of the grating medium were carried out by the proposed method. The widths of the resonance curves decrease with the increasing in the refractive index modulation. Moreover, the reflection coefficient also increases.

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