Microspectrometer uses donut-shaped resonators for higher resolution

July 1, 2011
An 81-channel microspectrometer with 2-μm-diameter singlemode microdonut resonators as its sensing elements is vastly shrunken in size compared to conventional spectrometers, but without sacrificing resolution.

An 81-channel microspectrometer with 2-μm-diameter singlemode microdonut resonators as its sensing elements is vastly shrunken in size compared to conventional spectrometers, but without sacrificing resolution. Fabricated on a silicon-on-insulator chip, the instrument was developed at the Georgia Institute of Technology (Atlanta, GA) for integrated lab-on-a-chip sensing applications.

Tunable-laser light in the 1550 nm range from an input-bus waveguide enters the microdonut array, with each microdonut resonator tapping only a small portion of the incoming light; each resonator is a unique channel and has a slightly different diameter. In a microdonut resonator, the fundamental radial mode interacts only with the donut’s outer wall; this is in contrast to a more conventional microring resonator, in which the light interacts with the inner and outer walls. Less interaction means a higher quality (Q) factor); the microdonuts have a loaded Q of 30,000 and an intrinsic Q of 80,000. The signal is collected by imaging from the top of the chip. The device achieved 0.6 nm resolution over a spectral range of more than 50 nm with a footprint less than 1 mm2. The instrument can be integrated with devices including sensors, optoelectronics, and microfluidic channels for use in biological, chemical, medical, and pharmaceutical applications.

Contact Ali Adibi at adibi@ece.gatech.edu.

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

Advancing Neuroscience Using High-Precision 3D Printing

March 7, 2025
Learn how Cold Spring Harbor Laboratory Used High-Precision 3D Printing to Advance Neuroscience Research using 3D Printed Optical Drives.

From Prototyping to Production: How High-Precision 3D Printing is Reinventing Electronics Manufacturing

March 7, 2025
Learn how micro 3D printing is enabling miniaturization. As products get smaller the challenge to manufacture small parts increases.

Sputtered Thin-film Coatings

Feb. 27, 2025
Optical thin-film coatings can be deposited by a variety of methods. Learn about 2 traditional methods and a deposition process called sputtering.

What are Notch Filters?

Feb. 27, 2025
Notch filters are ideal for applications that require nearly complete rejection of a laser line while passing as much non-laser light as possible.

Voice your opinion!

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