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Research on an Enhanced Detuned-Loading Effect in Integrated Two-Section DFB Lasers with High Modulation Bandwidths
Yunshan Zhang1, Hongming Gu1, Guolong Ma1
1College of Electronic and Optical Engineering and College of Flexible Electronics (Future Technology), Nanjing University of Posts and Telecommunications, Nanjing 210023, China.
Micromachines
|November 25, 2023
Summary
This study introduces a novel two-section distributed-feedback (TS-DFB) semiconductor laser that enhances modulation bandwidth using a detuned-loading effect and a π phase-shifted grating. This design significantly improves laser performance and yield for high-speed optical communication.
Area of Science:
- Photonics and Optical Engineering
- Semiconductor Device Physics
- High-Speed Communication Systems
Background:
- Distributed-feedback (DFB) lasers are crucial for optical communication.
- Direct modulation bandwidth limitations hinder higher data rates.
- The detuned-loading effect offers a method to enhance DFB laser performance.
Purpose of the Study:
- To propose and simulate a novel high-speed directly modulated two-section distributed-feedback (TS-DFB) semiconductor laser.
- To enhance the modulation bandwidth and yield of DFB lasers using the detuned-loading effect and a phase-shifted grating.
- To investigate the performance of an eight-channel laser array and compare phase-shifted gratings with uniform gratings.
Main Methods:
- Design of a grating structure using the reconstruction-equivalent-chirp (REC) technique.
- Introduction of a π phase shift into the reflection grating to create dual-falling edges in the reflection spectrum.
- Simulation of TS-DFB lasers with phase-shifted gratings and uniform gratings.
- Investigation of an eight-channel laser array with precise wavelength spacing.
Main Results:
- The TS-DFB laser with a π phase-shifted grating achieved a modulation bandwidth of approximately 24 GHz, a significant improvement over single DFB lasers (17.5 GHz).
- The dual-falling-edges structure enhances bandwidth even with thermal wavelength shifts, improving laser yield.
- An eight-channel laser array demonstrated precise wavelength spacing and a side-mode suppression ratio (SMSR) greater than 36 dB.
- Simulated TS-DFB lasers with uniform gratings showed inferior modulation characteristics compared to those with phase-shifted gratings.
Conclusions:
- The proposed TS-DFB semiconductor laser utilizing the detuned-loading effect and a π phase-shifted grating offers superior high-speed modulation performance.
- The dual-falling-edges design effectively broadens the modulation bandwidth and increases yield, making it suitable for demanding optical communication applications.
- Phase-shifted gratings are critical for achieving high modulation bandwidth in TS-DFB lasers, outperforming uniform gratings significantly.
