Single laser produces excessive-energy twin comb femtosecond pulses

Researchers occupy developed a brand original attain that uses a single laser cavity to originate two excessive-energy optical frequency combs emitting excessive-energy femtosecond pulses. The original pattern paves the attain for portable twin-comb gentle sources for applications equivalent to spectroscopy and precision distance measurement.

Optical frequency combs emit a spectrum of colors—or frequencies—which can be completely spaced love the enamel on a comb. Two such frequency combs with a runt diversified pulse repetition charges are in most cases blended to originate a twin-comb setup emitting a stream of short pulses.

Benjamin Willenberg from ETH Zurich in Switzerland will demonstrate the original attain at the all-virtual 2020 OSA Laser Congress, 13—16 October. The presentation will take spot Friday, 16 October at 08: 30 EDT.

“Our attain permits us to generate a pair of frequency combs with a little and passively proper offset of their repetition price,” said Willenberg. “This resolves the prolonged-standing misfortune of the excessive complexity of twin comb methods with out compromising on laser efficiency. Attainable sensing applications include time-domain spectroscopy for non-negative testing, ticket-gasoline detection for industrial and environmental monitoring, and laser ranging for machine vision applications.”Combining combs

The put together of pulses readily available from twin comb lasers are namely handy for extraordinarily at ease and fleet spectroscopy measurements and precisely measuring distances by job of laser ranging. Nevertheless, the need for 2 stabilized combs plus advanced synchronization electronics has restricted these measurements to the laboratory.

Within the original work, the researchers replaced these advanced methods with a less complicated passively proper optical attain. To complete twin-comb operation, they frail a single laser cavity multiplexed with birefringent calcite crystals to allow for lasing within the two polarization states. The researchers, for the first time, blended this birefringent crystal polarization multiplexing methodology with a diode-pumped strong-order laser crystal. The Yb:CaF2 produce crystal frail enables excessive-energy femtosecond pulse generation on account of its pleasing thermal properties and big emission spectrum.

For the rationale that original originate creates two frequency comb lasers the usage of a single optical cavity, it might perhaps perhaps enable the event of extra compact twin combs that offer flexibility in energy, wavelength, bandwidth, and pulse repetition charges.

With the original setup, the researchers carried out pulses with a 175-femtosecond duration and 440 mW of energy in two 1050-nm beams with a repetition price difference of 1 kHz. They demonstrated the steadiness of the repetition price difference by the usage of the laser to develop low-noise measurements on semiconductor offers the usage of asynchronous optical sampling. This fervent the usage of an ultrafast pulse to order off a reaction, and a second pulse to measure the brought on alternate.

Next steps for this technology include developing prototype methods in a strong and portable kit, demonstrating scientific and industrial applications, scaling to better powers and better repetition charges for sooner measurements, and developing channels to give the laser commercially.