Active stabilization of a rapidly chirped laser by an optoelectronic digital servo-loop control

Abstract

We propose and demonstrate a novel active stabilization scheme for wide and fast frequency chirps. The system measures the laser instantaneous frequency deviation from a perfectly linear chirp, thanks to a digital phase detection process, and provides an error signal that is used to servo-loop control the chirped laser. This way, the frequency errors affecting a laser scan over 10 GHz on the millisecond timescale are drastically reduced below 100 kHz. This active optoelectronic digital servo-loop control opens new and interesting perspectives in fields where rapidly chirped lasers are crucial.

An agile laser with ultra-low frequency noise and high sweep linearity

“…interferometers [12][13][14][15][16][17][18]. Recently, we have dramatically improved the performance of such systems by using a longer fiber spool and a heterodyne detection technique [19].…”

Solid state atomic processors for light

“…To meet the requirements of both architectures in terms of stability, scanning speed, range and repeatability, original tunable lasers have been developed [21,22] together with specific diagnostic, monitoring and control techniques [23]- [25].…”

Measurement of frequency sweep nonlinearity using atomic absorption spectroscopy

“…On the other hand, wavelength meters, Fabry-Perot etalon (FPE) or frequency comb can be used to monitor the laser frequency and measure the sweep rate of the diode laser [13][14][15][16], but the tuning of the laser must be much larger than the free spectral range of the FPE and only gives frequency information at discrete intervals. Another method uses an environmentally isolated reference interferometer to actively correct the frequency sweep nonlinearity [17][18][19]. The nonlinearity can also be compensated by externally triggering time domain sampling or using post processed resampling algorithms [20,21].…”