Efficient coupling from semiconductor lasers into single-mode fibers with tapered hemispherical ends.

Area of Science:

• Optics and Photonics
• Semiconductor Device Engineering

Background:

• Efficient optical coupling is crucial for integrating semiconductor lasers with fiber optic systems.
• Traditional flat-end fiber coupling can suffer from back-reflections, affecting laser stability.

Purpose of the Study:

• To describe an efficient coupling method using tapered hemispherical (TH) fibers for 1.3-microm semiconductor lasers.
• To evaluate the coupling efficiency and impact of back-reflections compared to conventional methods.

Main Methods:

• Fabrication of TH fibers by drawing in an arc discharge, optimizing hemisphere radius to ~20 microm.
• Characterization of coupling efficiency between semiconductor lasers and TH fibers.
• Assessment of laser characteristic changes due to reflected light for both TH and flat-end fibers.

Main Results:

• Achieved coupling efficiencies exceeding 35% with TH fiber coupling.
• Identified an optimal hemisphere radius of approximately 20 microm for efficient coupling.
• Demonstrated significantly reduced changes in laser characteristics from reflected light using TH fibers compared to flat-end fibers.
• Successfully fabricated stable coupling modules utilizing TH fiber technology.

Conclusions:

• Tapered hemispherical fiber coupling offers a highly efficient solution for 1.3-microm semiconductor laser integration.
• The TH fiber method enhances system stability by mitigating back-reflection issues.
• This technique is suitable for developing robust and reliable optical system modules.