Optical Resonator and Frequency Comb Made in Minutes
Lasers are used in a variety of applications, and as these applications become more advanced, the ability to measure that laser light must improve. Two devices that help with those measurements are optical resonators and frequency combs, which can respectively store and separate multiple frequencies. Researchers at NIST have recently developed a new way to produce these devices that can be completed in mere minutes.
The researchers start with a quartz rod, which is laser machined to the exact properties it needs to operate. Specifically it is the shape of small, smooth disks within the rod that form the resonators, and different diameters work with different frequencies of light. When infrared laser light is pumped into it, optical processes cause the single frequency to separate into multiple frequencies, forming a comb. Thanks to the quality factor of the rod, it is very efficient and requires little power from the pumping laser to form a cone.
The design the researchers developed takes just one minute to make, using a carbon dioxide laser, and another minute to form the frequency comb. In total the device costs about $10,000, which is considerably less than the $1 million or more for other designs that require a microfabrication system a cleanroom.