| dc.description.abstract | This study mainly simulates a ridge silicon waveguide with Bragg grating structure, which is characterized by reflecting a specific band, while wavelength in other bands passes through the waveguide normally. This component is often used as a signal acquisition component in WDM or DWDM systems, and the modulated Bragg grating structure through a apodization function to reduce the sidelobes. We use several apodization functions to investigate the sidelobe suppression, spectrum waveform, transmission, and reflection of each function.
We use GratingMOD to simulate and analyze Bragg grating waveguides. The numerical simulation method of this software is Coupled-Mode Theory (CMT). According to simulation results of strip waveguide and ridge waveguide in the literature, it is known that the ridge waveguide with the Bragg grating has a relatively narrow bandwidth, and it is easier to achieve the design of a bandwidth FWHM is 0.8 nm. Therefore, this study takes the ridge waveguide with the Bragg grating as the main structure, and explores the difference between the grating structure located on the side of the waveguide and the top layer of the waveguide. From the simulation results, we know that under the same structure length and similar bandwidth, the sidewall grating structure has higher loss, but the component volume is smaller; the top grating structure has less loss, but the component volume is larger.
Through the parameter analysis of the sidewall Bragg grating in ridge waveguide, we can understand the influence of each parameter on the bandwidth and reflection, and use the width of the slab as the main parameter to perform curve fitting with the bandwidth.
We use Hamming function, modify-Hamming function, raised-cosine function, Blackman function, Chen function, and Gaussian function to modulate the Bragg gratings. Apply each function to the side grating structure, group and discuss according to the FWHM of the function, and compare the function performance of sidewall and top grating structures under the similar transmission. When the length is 3000m, the modify-Hamming function has a sidelobe suppression of -24.9dB, and reflection is 99.9%, which is the highest among all functions, and the spectrum waveform is the sharpest; while the Chen function has the highest degree of sidelobe suppression of -95dB, and reflection is 95.2%. The higher the degree of sidelobe suppression, the higher the loss. However, the Gaussian function has higher loss than other functions at similar sidelobe suppression. When the sidewall and top grating structures have similar transmission, the function performances of two structures is also similar. | en_US |