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Fully-correlated multi-mode pumping for low-noise dual-frequency VECSELs
Optics Express
|November 25, 2018
Summary
We developed a novel pumping method for dual-frequency Vertical External Cavity Surface Emitting Lasers (VECSELs) that significantly reduces noise. This technique dramatically lowers phase noise in radio frequency beat notes, improving laser performance.
Area of Science:
- Optics and Photonics
- Laser Physics
- Quantum Optics
Background:
- Vertical External Cavity Surface Emitting Lasers (VECSELs) are crucial for various applications.
- Noise in laser systems, particularly phase noise, limits performance.
- Dual-frequency VECSELs offer unique capabilities but are susceptible to noise.
Purpose of the Study:
- To develop and demonstrate a noise reduction technique for class-A dual-frequency VECSELs.
- To investigate the impact of correlated pumping on laser mode intensity noise.
- To significantly reduce the phase noise of the radio frequency (RF) beat note generated by the VECSEL.
Main Methods:
- Implementation of a fully-correlated multi-mode pumping architecture.
- Utilizing amplitude division of a laser diode to create two in-phase correlated pump beams.
- Separately pumping the two orthogonally polarized modes of the VECSEL.
- Modeling the system using coupled rate equations with cross-saturation.
Main Results:
- Achieved strong, in-phase correlations between the intensities of the two lasing modes.
- Demonstrated a drastic reduction of 10-20 dB in phase noise power spectral density of the RF beat note.
- Observed phase noise falling below the detection floor above a few MHz.
- Validated results with a coupled rate equation model.
Conclusions:
- The fully-correlated multi-mode pumping architecture effectively reduces phase noise in dual-frequency VECSELs.
- The observed noise reduction is attributed to the in-phase correlation of pump intensity noise.
- Remaining noise is primarily due to thermal and technical sources, manageable with phase-locked loops.
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