On the role of shot noise in carrier‐envelope phase stabilization

Abstract

This paper represents a systematic investigation of detection shot noise in carrier-envelope phase (CEP) stabilization. Numerical simulations are conducted to calculate the influence of shot noise in laser oscillators. These results are compared with experimental results for Ti:sapphire lasers. It is found that shot noise imposes a limitation for obtaining sub-100 mrad CEP jitters. Careful interferometer design is necessary to push this limit toward 10 mrad. In contrast to oscillator stabilization, shot noise appears to play a much more restrictive role in amplifier stabilization. Using spectral interferometry together with spectral broadening in sapphire, it already appears practically challenging to reach sub-100 mrad jitters. Adaption of the optical nonlinearity in the broadening step appears key to further improvements of the CEP jitter of amplified systems. We believe that these improvements open a perspective for currently unfeasible applications of CEP stabilized pulses. Moreover, our considerations can be easily adapted to CEP stabilization of other laser types beyond Ti:sapphire.applications is the measurement of the carrier-envelope phase (CEP) of ultrashort laser pulses, which is the subject of this paper. In this article we systematically investigate the role of shot noise on different CEP measurement and stabilization schemes for oscillator and amplifier systems. We provide simulations to quantify the light level dependence of the shot noise induced phase jitter, and we show that the role of shot noise is often underestimated. Furthermore we discuss published experimental results of different CEP-stabilization schemes in the context of these simulations. Carrier-envelope phaseThe ability to control the phase of the carrier wave of ultrashort pulses with respect to its envelope [8-10] is not only relevant for the field of extreme nonlinear optics and attosecond science [11,12], but is also of great importance for frequency comb-based metrology [13][14][15]. In the past different schemes for the measurement of the CEP of ultrashort laser pulses have been proposed. The first attempt to measure the slippage rate of the CEP, i.e., the carrier-envelope offset (CEO) frequency f CEO , relied on the nonlinear C

On the origin of flicker noise in carrier-envelope phase stabilization

“…We are aware of only a single published OOL measurement of Er:fiber combs [10]. At high frequencies above ∼10 kHz, OOL measurements are dominated by a white noise background that stems from the detection of shot noise [5]. After carefully optimizing the beat note signalto-noise ratio, one can obtain shot noise limitations down to about S CEP ϕ f 10 −6 rad∕ Hz p…”

“…A number of authors have already identified various noise contributions to the residual CEP jitter [2,[5][6][7][8][9]. These measurements rely on a spectral analysis of the phase noise measured in an out-of-loop (OOL) interferometer, which is not directly involved in the stabilization of the CEP.…”

Direct carrier-envelope phase control of an amplified laser system

“…4 also shows the signal that is obtained when the interference is disabled by inserting a glass plate into the beam path of the f − 2f interferometer. The observed visibility of the beat note indicates that residual phase jitters well below 100 mrad are possible [16].…”

“…If the latter were true, one would expect to see a structured noise spectrum rather than a flat plateau. In particular, the practical absence of line frequency harmonics implies that we are actually seeing the limitations of the oscillator stabilization here [16]. In any case, it appears challenging to reduce this broadband 230 mrad noise signature with the traditional slow spectral interferometry approach [12] typically employed for amplifier stabilization.…”

Ultrarövid impulzusok erősítése következő generációs titán-zafír lézerrendszerekben

“…Ennek eredményeként az ultrarövid impulzusok CEP-jének detektálása és stabilizálása a lézeroszcillátorokkal és CPA rendszerekkel elérhető impulzusidő lerövidülésével egyre fontosabbá vált a 2000-es évek elején. Több kísérleti elrendezést is kifejlesztettek az elmúlt két évtizedben a CEP mérésére [128]. A CEP csúszásának, azaz az offszet frekvencia változásának megmérésére egy femtoszekundumos oszcillátor esetén elsőként egy nemlineáris keresztkorrelációs technikát alkalmaztak, amelyhez egy kellően nagy karhosszal rendelkező interferométert valósítottak meg [129].…”