Lasers to replace quartz technology

In a new discovery, researchers have found that lasers can safely replace years old quartz technology used in wristwatches or to transmit reliable signals to radios.

In lieu of a crystal, researchers at California Institute of Technology (Caltech) have developed a method to stabilise microwave signals in the range of gigahertz using a pair of laser beams as the reference.

"Our new method reverses the architecture used in standard crystal-stabilised microwave oscillators - the 'quartz' reference is replaced by optical signals much higher in frequency than the microwave signal to be stabilised," explained Kerry Vahala, a professor of information science and technology and applied physics at Caltech.

Nearly all electronics require devices called oscillators that create precise frequencies.

For nearly 100 years, these oscillators have relied upon quartz crystals to provide a frequency reference.

Quartz crystals "tune" oscillators by vibrating at relatively low frequencies - those that fall at or below the range of megahertz, or millions of cycles per second, like radio waves.

However, future high-end navigation systems, radar systems and even consumer electronics will require references beyond the performance of quartz.

In the new method called electro-optical frequency division, the optical reference used by researchers is a laser that looks like a tiny disk.

"At only six mm in diameter, the device is very small, making it particularly useful in compact photonic devices - devices powered by photons instead of electrons," said co-author Scott Diddams, a physicist at Maryland-based the National Institute of Standards and Technology.

The study appeared in the journal Science.