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Narrow linewidth semiconductor laser with a multi-period-delayed feedback photonic circuit
Optics Express
|April 27, 2022
Summary
A novel multi-period-delayed feedback photonic circuit significantly narrows semiconductor laser linewidth to ~2 kHz, a three-order-of-magnitude reduction. This technique also enhances laser frequency stability, improving performance across a tunable wavelength range.
Area of Science:
- Photonics
- Semiconductor Lasers
- Optical Engineering
Background:
- Narrow linewidth lasers are crucial for applications like optical communications and sensing.
- Distributed feedback (DFB) lasers offer wavelength tunability but often have limited linewidth performance.
Purpose of the Study:
- To design and demonstrate a photonic circuit for significantly reducing the linewidth of a DFB laser.
- To investigate the impact of the proposed circuit on laser frequency stability.
Main Methods:
- A multi-period-delayed feedback (MPDF) photonic circuit was designed using a Sagnac ring and two coupled rings.
- The MPDF circuit was coupled with a DFB laser diode (LD).
Main Results:
- The linewidth of the DFB-LD was narrowed to approximately 2 kHz, a reduction of three orders of magnitude.
- The linewidth reduction was maintained over a tunable wavelength range exceeding 3 nm.
- Laser frequency stability was improved, with frequency fluctuations reduced by nearly 8 times compared to the DFB-LD alone.
Conclusions:
- The MPDF photonic circuit effectively narrows the linewidth of DFB-LDs.
- The proposed technique offers a robust method for enhancing laser frequency stability and performance.
- This approach is suitable for applications requiring narrow linewidth and stable semiconductor lasers.
