Optical coupling method utilizing a lensed fiber integrated with a long-period fiber grating

Area of Science:

• Optical Engineering
• Fiber Optics Communications
• Photonics

Background:

• Efficient optical coupling is crucial for high-performance fiber optic systems.
• Existing coupling methods face limitations in working distance and efficiency.
• Long-period fiber gratings (LPFGs) offer potential for optical signal manipulation.

Purpose of the Study:

• To propose and validate a novel optical coupling scheme integrating a lensed fiber with an LPFG.
• To enhance coupling efficiency and working distance in fiber optic connections.
• To evaluate the performance in both single-mode fiber to single-mode fiber (SMF-to-SMF) and laser-diode to single-mode fiber (LD-to-SMF) configurations.

Main Methods:

• Development of a novel optical coupling design combining a lensed fiber and an LPFG.
• Experimental validation in two distinct coupling scenarios: SMF-to-SMF and LD-to-SMF.
• Systematic measurement of coupling efficiency, working distance, and 1-dB tolerances (longitudinal and transverse).

Main Results:

• The integrated LPFG scheme demonstrated improved coupling efficiency over extended working distances compared to schemes without an LPFG.
• For SMF-to-SMF coupling, efficiencies of ~78% were achieved with a ~250 microm working distance.
• For LD-to-SMF coupling, efficiencies of ~35% were achieved with a ~110 microm working distance, alongside improved tolerances.

Conclusions:

• The proposed lensed fiber integrated with LPFG scheme is a viable method for enhancing optical coupling.
• This novel approach offers significant improvements in coupling efficiency and working distance for critical fiber optic applications.
• The results indicate potential for broader adoption in telecommunications and optical sensing.