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Graphene-Coupled Terahertz Semiconductor Lasers for Enhanced Passive Frequency Comb Operation
Hua Li1,2, Ming Yan3, Wenjian Wan1
1Key Laboratory of Terahertz Solid State Technology Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences 865 Changning Road Shanghai 200050 China.
Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|October 23, 2019
Summary
A new passive terahertz frequency comb was created using graphene in a quantum cascade laser (QCL). This breakthrough enables enhanced precision for terahertz spectroscopy and nonlinear photonics applications.
Area of Science:
- Photonics
- Quantum Cascade Lasers
- Materials Science
Background:
- Optical frequency combs are crucial for precision spectroscopy and metrology.
- Terahertz combs have been achieved in quantum cascade lasers (QCLs) using active methods or dispersion compensation.
- Passive comb formation in terahertz semiconductor lasers is challenging due to insufficient nonlinearities.
Purpose of the Study:
- To demonstrate a passive terahertz frequency comb using graphene integrated into a QCL compound cavity.
- To overcome the limitations of conventional saturable absorbers for terahertz comb generation.
Main Methods:
- Coupling a multilayer graphene sample into a QCL compound cavity.
- Utilizing graphene's saturable absorption and dispersion compensation properties.
- Validating comb operation through on-chip dual-comb measurements and terahertz pump-probe spectroscopy.
Main Results:
- Demonstrated a passive terahertz frequency comb with self-stabilized modes.
- Achieved record intermode beat note linewidths as low as 700 Hz.
- Confirmed comb operation and characterized the emitted optical pulse.
Conclusions:
- Graphene integration offers a novel approach for passive terahertz frequency comb generation in QCLs.
- The enhanced performance is attributed to graphene's saturable absorption and dispersion compensation.
- This work opens new avenues for high-precision terahertz spectroscopy and nonlinear photonics.
