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Schilt, Stephane
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Schilt, Stephane
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- PublicationAccès libreAbsolute frequency referencing in the long wave infrared using a quantum cascade laser frequency comb(2022-4-4)
; ;Gianella, Michele ;Jouy, Pierre ;Kapsalidis, Filippos ;Shahmohammadi, Mehran ;Beck, Mattias; ; ;Hugi, Andreas ;Faist, Jérôme ;Emmenegger, Lukas; Optical frequency combs (OFCs) based on quantum cascade lasers (QCLs) have transformed mid-infrared spectroscopy. However, QCL-OFCs have not yet been exploited to provide a broadband absolute frequency reference. We demonstrate this possibility by performing comb-calibrated spectroscopy at 7.7 µm (1305 cm−1) using a QCL-OFC referenced to a molecular transition. We obtain 1.5·10−10 relative frequency stability (100-s integration time) and 3·10−9 relative frequency accuracy, comparable with state-of-the-art solutions relying on nonlinear frequency conversion. We show that QCL-OFCs can be locked with sub-Hz-level stability to a reference for hours, thus promising their use as metrological tools for the mid-infrared. - PublicationAccès libreCoherently-averaged dual comb spectrometer at 7.7 µm with master and follower quantum cascade lasers(2021-6)
; ; ;Terrasanta, Giulio; ; ;Gianella, Michele ;Jouy, Pierre ;Kapsalidis, Filippos ;Shahmohammadi Mehran, Mehran ;Beck Matthias, Matthias; ;Faist, Jérôme ;Emmenegger, Lukas; ;Hugi, AndreasWe demonstrate coherent averaging of the multi-heterodyne beat signal between two quantum cascade laser frequency combs in a master-follower configuration. The two combs are mutually locked by acting on the drive current to control their relative offset frequency and by radio-frequency extraction and injection locking of their intermode beat signal to stabilize their mode spacing difference. By implementing an analog common-noise subtraction scheme, a reduction of the linewidth of all heterodyne beat notes by five orders of magnitude is achieved compared to the free-running lasers. We compare stabilization and post-processing corrections in terms of amplitude noise. While they give similar performances in terms of signal-to-noise ratio, real-time processing of the stabilized signal is less demanding in terms of computational power. Lastly, a proof-of-principle spectroscopic measurement was performed, showing the possibility to reduce the amount of data to be processed by three orders of magnitude, compared to the free-running system. - PublicationMétadonnées seulement
- PublicationMétadonnées seulementPhase-stabilization of the carrier-envelope-offset frequency of a SESAM modelocked thin disk laser(2013)
;Klenner, Alexander ;Emaury, Florian ;Schriber, Cinia ;Diebold, Andreas ;Saraceno, Clara Jody; ;Keller, Ursula - PublicationAccès libreUltra-stable microwave generation with a diode-pumped solid-state laser in the 1.5-?m range(2013)
; ; ; ; ;Grop, Serge ;Dubois, Benoît ;Giordano, Vincent - PublicationAccès libre
- PublicationAccès libreNoise properties of an optical frequency comb from a SESAM-modelocked 1.5 µm solid-state laser stabilized to the 10E-13 level(2012-5-26)
; ; ; ; ;Stumpf, Max; ;Pekarek, Selina ;Oehler, Andreas; ;Keller, UrsulaWe present a detailed investigation of the noise properties of an optical frequency comb generated from a femtosecond diode-pumped solid-state laser operating in the 1.5-μm spectral region. The stabilization of the passively mode-locked Er:Yb:glass laser oscillator, referred to as ERGO, is achieved using pump power modulation for the control of the carrier envelope offset (CEO) frequency and by adjusting the laser cavity length for the control of the repetition rate. The stability and the noise of the ERGO comb are characterized in free-running and in phase-locked operation by measuring the noise properties of the CEO, of the repetition rate, and of a comb line at 1558 nm. The comb line is analyzed from the heterodyne beat signal with a cavity-stabilized ultra-narrow-linewidth laser using a frequency discriminator. Two different schemes to stabilize the comb to a radio-frequency (RF) reference are compared. The comb properties (phase noise, frequency stability) are limited in both cases by the RF oscillator used to stabilize the repetition rate, while the contribution of the CEO is negligible at all Fourier frequencies, as a consequence of the low-noise characteristics of the CEO-beat. A linewidth of ≈150 kHz and a fractional frequency instability of 4.2×1E−13 at 1 s are obtained for an optical comb line at 1558 nm. Improved performance is obtained by stabilizing the comb to an optical reference, which is a cavity-stabilized ultra-narrow linewidth laser at 1558 nm. The fractional frequency stability of 8×1E−14 at 1 s, measured in preliminary experiments, is limited by the reference oscillator used in the frequency comparison. - PublicationAccès libre
- PublicationAccès libreFully stabilized optical frequency comb with sub-radian CEO phase noise from a SESAM-modelocked 1.5-µm solid-state laser(2011)
; ; ; ; ;Stumpf, Max C.; ;Pekarek, Selina ;Oehler, Andreas E. H.; ;Keller, UrsulaWe report the first full stabilization of an optical frequency comb generated from a femtosecond diode-pumped solid-state laser (DPSSL) operating in the 1.5-μm spectral region. The stability of the comb is characterized in free-running and in phase-locked operation by measuring the noise properties of the carrier-envelope offset (CEO) beat, of the repetition rate, and of a comb line at 1558 nm. The high Q-factor of the semiconductor saturable absorber mirror (SESAM)-modelocked 1.5-µm DPSSL results in a low-noise CEO-beat, for which a tight phase lock can be much more easily realized than for a fiber comb. Using a moderate feedback bandwidth of only 5.5 kHz, we achieved a residual integrated phase noise of 0.72 rad rms for the locked CEO, which is one of the smallest values reported for a frequency comb system operating in this spectral region. The fractional frequency stability of the CEO-beat is 20‑fold better than measured in a standard self-referenced commercial fiber comb system and contributes only 10−15 to the optical carrier frequency instability at 1 s averaging time. - PublicationAccès libreFrequency stability of a dual wavelength quantum cascade laser
;Sargachev, Ilia ;Maulini, Richard ;Gresch, Tobias ;Blaser, Stéphane ;Bismuto, Alfredo ;Müller, Antoine ;Bidaux, Yves; We characterized the dual wavelength operation of a distributed Bragg reflector (DBR) quantum cascade laser (QCL) operating at 4.5 μm using two independent optical frequency discriminators. The QCL emits up to 150 mW fairly evenly distributed between two adjacent Fabry-Perot modes separated by ≈11.6 GHz. We show a strong correlation between the instantaneous optical frequencies of the two lasing modes, characterized by a Pearson correlation coefficient of 0.96. As a result, we stabilized one laser mode of the QCL to a N2O transition using a side-of-fringe locking technique, reducing its linewidth by a factor 6.2, from 406 kHz in free-running operation down to 65 kHz (at 1-ms observation time), and observed a simultaneous reduction of the frequency fluctuations of the second mode by a similar amount, resulting in a linewidth narrowing by a factor 5.4, from 380 kHz to 70 kHz. This proof-of-principle demonstration was performed with a standard DBR QCL that was not deliberately designed for dual-mode operation. These promising results open the door to the fabrication of more flexible dual-mode QCLs with the use of specifically designed gratings in the future.