Rapid, k-space linear wavelength scanning laser source based on recirculating frequency shifter.

Area of Science:

• Photonics and Optical Engineering
• Laser Physics
• Signal Processing

Background:

• Wavelength scanning fiber lasers are crucial for applications requiring tunable light sources.
• Recirculating frequency shifting (RFS) offers a method for wavelength scanning but is susceptible to amplified spontaneous emission (ASE) noise accumulation.
• Existing methods struggle to maintain signal quality over extended scanning periods due to noise.

Purpose of the Study:

• To propose and demonstrate a k-space linear and self-clocked wavelength scanning fiber laser source.
• To overcome the signal degradation caused by amplified spontaneous emission (ASE) noise in RFS systems.
• To enhance the signal-to-noise ratio (SNR) of the generated pulsed signal.

Main Methods:

• Utilized a recirculating frequency shifting (RFS) technique employing a high-speed electro-optic dual parallel Mach-Zehnder modulator.
• Implemented carrier suppressed single sideband modulation for RFS.
• Introduced a gated short pulse into an amplified RFS loop.
• Incorporated a modulated optical switch to attenuate in-band ASE noise at the end of each scanning period.

Main Results:

• Successfully demonstrated a k-space linear and self-clocked wavelength scanning fiber laser.
• Achieved wavelength scanning ranges of 6.1 nm and 7.2 nm with frequency shifting of 20 GHz and 30 GHz, respectively.
• Significantly enhanced the signal-to-noise ratio (SNR) of the temporal pulsed signal by mitigating ASE noise.

Conclusions:

• The proposed RFS-based wavelength scanning fiber laser effectively overcomes ASE noise limitations.
• The integration of a modulated optical switch is key to improving signal quality and enabling robust wavelength scanning.
• This technology offers improved performance for tunable pulsed laser sources.