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Wavelength switchable flat-top all-fiber comb filter based on a double-loop Mach-Zehnder interferometer.
Ai-Ping Luo1, Zhi-Chao Luo, Wen-Cheng Xu
1Laboratory of Photonic Information Technology, School of information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou, Guangdong 510006, PR China.
Optics Express
|April 15, 2010
Summary
This study introduces a novel all-fiber comb filter with a switchable wavelength and flat-top spectral response. The proposed device, based on a double-loop Mach-Zehnder interferometer, achieves a wide flat-top passband, crucial for optical communications.
Area of Science:
- Photonics
- Optical Engineering
- Fiber Optics
Background:
- Mach-Zehnder interferometers are fundamental components in optical signal processing.
- Achieving flat-top spectral responses in fiber optic filters is essential for applications like wavelength division multiplexing.
- Controlling polarization states is key to manipulating interference patterns in optical devices.
Purpose of the Study:
- To propose and demonstrate a novel wavelength switchable all-fiber comb filter.
- To achieve a flat-top spectral response in the proposed filter design.
- To analyze and experimentally verify the performance of the double-loop Mach-Zehnder interferometer-based filter.
Main Methods:
- Utilizing a double-loop Mach-Zehnder (M-Z) interferometer architecture.
- Incorporating a rotatable polarizer and a polarization controller (PC) within the M-Z interferometer.
- Employing a non-3dB coupler in the second loop of the M-Z interferometer.
- Optimizing polarization states of input light and PC settings for desired filter characteristics.
Main Results:
- Demonstrated a wavelength switchable all-fiber comb filter with a flat-top spectral response.
- Achieved a measured 1 dB bandwidth of 0.51 nm with a channel spacing of 0.98 nm.
- The flat-top passband (1 dB bandwidth) extended to approximately 50% of the comb spacing, confirming theoretical predictions.
Conclusions:
- The proposed double-loop M-Z interferometer design successfully enables wavelength switchable all-fiber comb filtering.
- The filter exhibits a desirable flat-top passband, with its width being a significant portion of the channel spacing.
- This technology holds promise for advanced optical communication systems requiring precise spectral control.
