Diamond Raman laser has intrinsically stable single-longitudinal-mode output

Aug. 3, 2016
Near-IR emitter achieves stability of 80 MHz because it is free of spatial hole burning. 

A study by researchers at Macquarie University (Sydney, Australia) has led to a new way to make ultrastable narrow-linewidth lasers that avoids spatial hole burning, which is the problem ordinarily responsible for destabilizing and broadening a laser’s frequency.1 The results are hoped to enable the next generation of lasers required for atomic clocks, remote sensing of greenhouse gases, and atom trapping, as well as in gravitational-wave astronomy.

The laser was based on the diamond Raman laser technology developed at Macquarie University and reported in 2008. Using a low-birefringence single-crystal diamond made by Element Six (Ascot, England), Oliver Lux and Rich Mildren demonstrated stable single-frequency operation using a simple laser-cavity design that would normally be highly susceptible to destabilization. In particular, they placed the diamond, which was 8 × 4 × 1.2 mm in size, at the midpoint of a long standing-wave cavity, a configuration normally considered a “worst-case scenario” for inducing the instabilities that cause polychromatic behavior to occur.

80 MHz stability

The laser’s stability was on the order of 80 MHz over periods of about a minute for a 1.2 W output power (and 20 GHz for a 10 W output due to mode-hopping and multimode operation at the higher power). The single-mode laser’s wavelength could be tuned from 1238.1 to 1241.9 nm by varying the pump laser’s wavelength.

“Lasers are often thought of as being highly monochromatic, that is, of a single frequency, but in most cases their spectral purity is corrupted by a destabilizing effect referred to as spatial-hole burning. This effect causes the laser frequency to chaotically jump between a grouping of many closely spaced lines,” says Associate Professor Mildren. “The problem is avoided in our case by using a light-amplifying medium that relies on stimulated scattering rather than an excited medium that contains energy such as a population inversion.”

He adds, “Our finding provides greater freedoms for laser design and potentially much simpler, more robust systems. And, since the light-amplifier engine works using a fundamentally different principle to most lasers we are familiar with, a completely different range of materials may be used including those with extraordinary properties such as diamond. This promises a method of generating single-frequency lasers over a wider choice of wavelengths and with potentially very high power.”

Source: http://www.mq.edu.au/newsroom/2016/08/03/brilliant-lasers-diamond-provides-new-approach-to-ultra-pure-frequency-lasers/

REFERENCE:

1. O. Lux et al., Optica (2016); doi: 10.1364/OPTICA.3.000876

About the Author

John Wallace | Senior Technical Editor (1998-2022)

John Wallace was with Laser Focus World for nearly 25 years, retiring in late June 2022. He obtained a bachelor's degree in mechanical engineering and physics at Rutgers University and a master's in optical engineering at the University of Rochester. Before becoming an editor, John worked as an engineer at RCA, Exxon, Eastman Kodak, and GCA Corporation.

Sponsored Recommendations

Brain Computer Interface (BCI) electrode manufacturing

Jan. 31, 2025
Learn how an industry-leading Brain Computer Interface Electrode (BCI) manufacturer used precision laser micromachining to produce high-density neural microelectrode arrays.

Electro-Optic Sensor and System Performance Verification with Motion Systems

Jan. 31, 2025
To learn how to use motion control equipment for electro-optic sensor testing, click here to read our whitepaper!

How nanopositioning helped achieve fusion ignition

Jan. 31, 2025
In December 2022, the Lawrence Livermore National Laboratory's National Ignition Facility (NIF) achieved fusion ignition. Learn how Aerotech nanopositioning contributed to this...

Nanometer Scale Industrial Automation for Optical Device Manufacturing

Jan. 31, 2025
In optical device manufacturing, choosing automation technologies at the R&D level that are also suitable for production environments is critical to bringing new devices to market...

Voice your opinion!

To join the conversation, and become an exclusive member of Laser Focus World, create an account today!