Laser-diode wavelength tuning based on butt coupling into an optical fiber

Area of Science:

• Photonics
• Semiconductor Lasers
• Optical Engineering

Background:

• Fabry-Perot laser diodes are crucial components in optical systems.
• External cavities are used for wavelength tuning, but short cavities present challenges.
• Butt coupling offers a method to integrate laser diodes with other optical components.

Purpose of the Study:

• To investigate controlled wavelength tuning of a high-output-power laser diode using an extremely short external cavity.
• To explore the feasibility of butt coupling for effective wavelength tuning.
• To develop and validate an analytical model for the observed tuning behavior.

Main Methods:

• Fabrication of an extremely short external cavity by butt coupling a Fabry-Perot laser diode to a waveguide or fiber.
• Experimental tuning of the laser diode over a wide wavelength range while maintaining constant current and temperature.
• Development of an analytical model incorporating multiple reflections and modal overlap integrals.

Main Results:

• Achieved controlled wavelength tuning of a high-output-power laser diode over a range of 15 nm.
• Maintained constant driving current and temperature during tuning.
• Observed repeatable single-mode or multimode operation at specific points within the tuning range.
• Demonstrated good agreement between the analytical model and experimental results.

Conclusions:

• Extremely short external cavities realized via butt coupling are effective for controlled wavelength tuning of laser diodes.
• The developed analytical model accurately predicts the experimental tuning behavior.
• This technique enables wide-range, stable wavelength tuning for high-output-power laser diodes.