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Extended-bandwidth frequency sweeps of a distributed feedback laser using combined injection current and temperature
Gerald Hefferman1, Zhen Chen1, Tao Wei1
1Department of Electrical, Computer, and Biomedical Engineering, University of Rhode Island, Kingston, Rhode Island 02881, USA.
The Review of Scientific Instruments
|August 3, 2017
Summary
Researchers developed a novel two-step technique to generate an extended-bandwidth frequency sweep from a single distributed feedback (DFB) laser, achieving a 510.9 GHz bandwidth for enhanced sensing applications.
Area of Science:
- Photonics
- Optical Engineering
- Laser Technology
Background:
- Semiconductor lasers, such as distributed feedback (DFB) lasers, are crucial for optical sensing.
- Extending the frequency sweep bandwidth of these lasers is essential for high-resolution measurements.
- Current techniques often require complex setups or multiple laser sources.
Purpose of the Study:
- To demonstrate a cost-effective method for generating an extended-bandwidth frequency sweep using a single DFB laser.
- To achieve a total bandwidth of 510.9 GHz for advanced optical sensing.
- To validate the technique's utility in coherent optical frequency domain reflectometry (OFDR).
Main Methods:
- A two-step frequency sweep generation process involving injection current modulation and temperature modulation of a DFB laser.
- Utilizing a digital optical phase-lock loop for linear frequency chirp generation during current modulation.
- Combining multiple, partially overlapping spectra through cross-correlation and averaging to form a single broadband spectrum.
Main Results:
- Successfully generated a broadband frequency sweep with a total bandwidth of 510.9 GHz.
- Demonstrated the technique's application in a coherent OFDR system.
- Resolved both the periodicity of a fiber Bragg grating (FBG) and individual reflector elements using the generated sweep.
Conclusions:
- The developed technique effectively extends the sweeping bandwidth of a single DFB laser.
- This method offers a promising approach for frequency-based sensing applications requiring broad bandwidths.
- The technique's successful application in OFDR highlights its potential for high-resolution optical measurements.
