Wavelength-Flexible Thulium-Doped Fiber Laser Based on Digital Micromirror Array.

Area of Science:

• Optics and Photonics
• Laser Physics
• Fiber Lasers

Background:

• Thulium-doped fiber lasers (TDFLs) are crucial for applications in the 2-micron spectral region.
• Traditional wavelength tuning methods for TDFLs can be complex and limited in flexibility.
• Digital micromirror devices (DMDs) offer advanced spatial light modulation capabilities.

Purpose of the Study:

• To demonstrate a wavelength-tunable thulium-doped fiber laser system.
• To investigate the use of a digital micromirror device (DMD) for flexible wavelength control.
• To analyze the performance and stability of the proposed laser system.

Main Methods:

• Integration of a digital micromirror device (DMD) with a fixed grating in a thulium-doped fiber laser cavity.
• Analysis of DMD diffraction properties and steering efficiency using two-dimensional grating theory.
• Spatially modulating reflective patterns on the DMD to control the lasing wavelength.

Main Results:

• Achieved stable, fast, and flexible wavelength tuning of the TDFL from 1930 nm to 2000 nm.
• Demonstrated a wavelength tuning accuracy of 0.1 nm.
• Obtained a side-mode suppression ratio greater than 50 dB and a 3 dB linewidth less than 0.05 nm.
• Exhibited low wavelength drift (<0.05 nm) and power fluctuation (<0.1 dB) within 1 hour at room temperature.

Conclusions:

• The DMD-based approach provides an effective method for achieving precise and flexible wavelength tuning in TDFLs.
• The demonstrated laser system offers excellent spectral performance and stability for 2-micron applications.
• This technology opens new possibilities for tunable laser sources in spectroscopy, sensing, and medical applications.