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Long-period gratings in planar optical waveguides
Vipul Rastogi1, Kin Seng Chiang
1Department of Electronic Engineering, Optoelectronics Research Centre, City University of Hong Kong, China. vipul.rastogi@cityu.edu.hk
Applied Optics
|October 25, 2002
Summary
We theoretically analyzed light propagation in a four-layer planar waveguide with a long-period grating (LPG). This structure couples light to cladding modes, creating sharp rejection bands for integrated-optic devices.
Area of Science:
- Optics and Photonics
- Materials Science
Background:
- Planar waveguides are fundamental components in integrated optics.
- Long-period gratings (LPGs) are used for wavelength-selective light manipulation.
Purpose of the Study:
- To theoretically analyze light propagation in a four-layer planar waveguide featuring an LPG.
- To investigate the coupling of light from guided modes to cladding modes.
- To explore the potential of LPG-based waveguides for integrated-optic devices.
Main Methods:
- Theoretical analysis using coupled-mode theory.
- Numerical simulations to study transmission spectra and resonance wavelengths.
Main Results:
- Demonstrated coupling of fundamental guided mode to cladding modes at specific resonance wavelengths.
- Observed sharp rejection bands in the waveguide's transmission spectrum.
- Showed that resonance wavelengths and transmission spectra are tunable via waveguide and grating parameters.
Conclusions:
- Waveguide-based LPGs are effective for creating wavelength-selective filtering.
- The tunability of LPG parameters offers flexibility in device design.
- These structures are promising for developing integrated-optic devices like filters, switches, and sensors.