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Megahertz scan rates enabled by optical sampling by repetition-rate tuning.
1School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK. d.bajek@hw.ac.uk.
Scientific Reports
|November 27, 2021
Summary
We achieved record megahertz scan rates using optical sampling by repetition-rate tuning (OSBERT). This breakthrough enables faster time-resolved spectroscopy by electronically tuning a compact laser diode.
Area of Science:
- Optics and Photonics
- Ultrafast Spectroscopy
- Laser Physics
Background:
- Time-resolved spectroscopy traditionally faces limitations in scan speed.
- Existing optical sampling by repetition-rate tuning (OSBERT) methods have slower scan rates.
- Compact and tunable pulsed laser sources are crucial for advanced spectroscopic techniques.
Purpose of the Study:
- To demonstrate optical sampling by repetition-rate tuning (OSBERT) at unprecedented megahertz scan rates.
- To develop a novel system for high-speed electronic modulation of a laser diode's repetition rate.
- To enable real-time acquisition of ultrafast optical phenomena.
Main Methods:
- Utilized a compact, tunable 2-section passively mode-locked laser diode (MLLD) as the pulsed source.
- Implemented an imbalanced Michelson interferometer configuration with a passive delay line (PDL).
- Employed impedance-matching and a signal generator for megahertz-frequency sinusoidal electrical biasing of the MLLD's saturable absorber.
Main Results:
- Achieved record megahertz optical sampling scan rates, a three-order-of-magnitude improvement over previous OSBERT demonstrations.
- Successfully demonstrated real-time acquisition of a cross-correlation trace of two ultrashort optical pulses within 1 microsecond.
- Validated the electronic tunability of the MLLD's repetition rate from sub-hertz to megahertz frequencies.
Conclusions:
- The developed OSBERT system offers groundbreaking megahertz scan rates for time-resolved spectroscopy.
- This advancement paves the way for highly competitive scan rates in various spectroscopic applications.
- Potential applications include pump-probe spectroscopy, metrology, and other ultrafast optical measurements.
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