Tunable erbium-doped microbubble laser fabricated by sol-gel coating

Area of Science:

• Photonics and Optical Engineering
• Materials Science
• Nanotechnology

Background:

• Whispering gallery mode resonators are crucial for various optical applications.
• Sol-gel coatings offer versatile methods for material functionalization.
• Erbium (Er3+) doping is essential for achieving laser emission in the telecommunication band.

Purpose of the Study:

• To create an active microbubble whispering gallery resonator using sol-gel coating.
• To demonstrate laser action in an erbium-doped microbubble resonator.
• To investigate the tunability of the laser wavelength via external stimuli.

Main Methods:

• Fabrication of a microbubble resonator by applying an erbium-doped sol-gel to a tapered microcapillary.
• Pumping the doped microbubble at 980 nm to induce lasing.
• Utilizing aerostatic pressure to tune the whispering gallery modes and laser wavelength.

Main Results:

• Successful fabrication of a microbubble resonator with a wall thickness of 1.3 μm and diffused rare earth ions.
• Demonstration of laser emission at 1535 nm, corresponding to the Er3+ emission band.
• Observation of up to 240 pm wavelength tuning with 2 bar of applied pressure.

Conclusions:

• The sol-gel coating successfully transforms the microbubble resonator into an active laser device.
• The erbium-doped microbubble resonator exhibits tunable laser emission.
• The developed device shows potential as a compact and tunable laser source for optical applications.