Whispering-gallery resonator generates CW fourth-harmonic UV light

A gradient-index (GRIN) lens supplies IR light to a diamond prism that couples the light into a lithium niobate whispering-gallery resonator. The generated near-IR, visible, and UV light are collected by a multimode fiber. (Photo courtesy of Mona Jarrahi)

Ann Arbor, MI--When only 200 mW of IR light is coupled into a millimeter-scale whispering gallery resonator made of lithium niobate, it can produce cascaded-harmonic generation up to the fourth harmonic, serving as a compact, low-power source of UV light.1 The device, developed by researchers at the University of Michigan, could become part of future microscopes, information-storage systems, and chemical-analysis instruments.

The research was led by Mona Jarrahi and Tal Carmon, assistant professors in the Department of Electrical Engineering and Computer Science. The experiment was performed by Jeremy Moore and Matthew Tomes, both graduate students in the same department.

The resonator takes its IR input from relatively cheap telecommunications-compatible lasers. "We optimized the structure to achieve high gain over a broad range of optical wavelengths," says Jarrahi. "This allows us to make low-cost, wavelength-tunable ultraviolet sources using low IR power levels."

Lasers get progressively more difficult to generate and more inefficient, as engineers aim for shorter wavelengths, say the researchers. "As we go from green to blue, the efficiency of the laser goes down. Going to UV lasers is even harder," notes Jarrahi. "This principle was first suggested by Einstein and is the reason why green laser pointers do not actually contain a green laser. It is actually a red laser and its wavelength is divided by two to become green light."

The nonlinear-crystal resonator has variable poling and a resonator quality (Q) factor of 107.


1. Jeremy Moore et al., Optics Express, Vol. 19, No. 24, p. 24139 (2011).


A long way from the ruby laser

Most Popular Articles


Ray Optics Simulations with COMSOL Multiphysics

The Ray Optics Module can be used to simulate electromagnetic wave propagation when the wavelength is much smaller than the smallest geometric entity in the ...

Multichannel Spectroscopy: Technology and Applications

This webcast, sponsored by Hamamatsu, highlights some of the photonic technology used in spectroscopy, and the resulting applications.

Handheld Spectrometers

Spectroscopy is a powerful and versatile tool that traditionally often required a large and bulky instrument. The combination of compact optics and modern pa...

Fracking, climate change, and lasers:  new tools to reduce fugitive methane emissions

This webcast, sponsored by Hamamatsu Corporation, covers recent developments and field deployments of compact quantum-cascade-laser (QCL)-based methane senso...
White Papers

Narrow-line fiber-coupled modules for DPAL pumping

A new series of fiber coupled diode laser modules optimized for DPAL pumping is presented, featur...

Accurate LED Source Modeling Using TracePro

Modern optical modeling programs allow product design engineers to create, analyze, and optimize ...

Optical Isolators Improve Engraving Performance of Pulsed Fiber Lasers

The deleterious effects of back reflections on pulsed fiber lasers used in marking and engraving ...
Technical Digests

ADHESIVES, SEALANTS, AND COATINGS: Solutions for optical technologies

A vast array of optical systems of various types and degrees of complexity require the use of adh...

WAVELENGTH-SWEPT LASERS: Dispersion-tuned fiber laser sweeps over a 140 nm range for OCT

By eliminating the use of mechanical tunable filters and instead tuning by intensity-modulation i...

Keeping pace with developments in photonic materials research

For demanding or custom spectroscopy solutions, care must be taken in selecting and integrating a...

HIGH-POWER FIBER LASERS: Working in the kilowatt regime

High-power materials-processing fiber lasers are available in an increasing variety of forms, as ...

Click here to have your products listed in the Laser Focus World Buyers Guide.
Social Activity
Copyright © 2007-2014. PennWell Corporation, Tulsa, OK. All Rights Reserved.PRIVACY POLICY | TERMS AND CONDITIONS