Polarization-dependent fluoride fiber coupler and application to pulsed laser triggering.

Area of Science:

• Optics and Photonics
• Materials Science
• Fiber Laser Technology

Background:

• Optical fiber couplers (OFCs) are crucial components in fiber optic systems.
• Polarization-dependent OFCs are essential for controlling light polarization.
• ZBLAN glass offers unique properties for mid-infrared (MIR) applications.

Purpose of the Study:

• To introduce the first ZBLAN-based polarization-dependent optical fiber coupler (OFC).
• To characterize the performance of the ZBLAN OFC in terms of polarization extinction ratio (PER) and coupling ratio.
• To demonstrate the application of the ZBLAN OFC in generating fundamental solitons using nonlinear polarization evolution in a mode-locked fiber laser.

Main Methods:

• Fabrication of a single-mode, polarization-dependent optical fiber coupler using ZBLAN soft glass.
• Characterization of the OFC's polarization extinction ratio (PER) and coupling ratio with unpolarized light input at a wavelength of 1.918 μm.
• Integration of the ZBLAN OFC into a mode-locked fiber laser setup to trigger soliton formation via nonlinear polarization evolution.

Main Results:

• The ZBLAN OFC achieved a PER of 2.5 dB/4.0 dB at the through-port/cross-port.
• With unpolarized input, the OFC exhibited a coupling ratio of 73.5%/26.5% and an excess loss of 1.47 dB at 1.918 μm.
• The OFC facilitated the generation of fundamental solitons with a duration of 1.83 ps at 1.918 μm, supporting at least 320 mW of optical power.

Conclusions:

• The developed ZBLAN-based polarization-dependent OFC is a novel component for MIR fiber optics.
• The OFC effectively controls light polarization and enables soliton generation in fiber lasers.
• This technology is expected to significantly impact the field of mid-infrared fiber optics.