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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)
; ; ; ; 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)
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- PublicationAccès libreUltra-stable microwave generation with a diode-pumped solid-state laser in the 1.5-?m range(2013)
; ; ; ; - 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)
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- PublicationAccès libreFully stabilized optical frequency comb with sub-radian CEO phase noise from a SESAM-modelocked 1.5-µm solid-state laser(2011)
; ; ; ; ; ; - PublicationAccès libreGigahertz frequency comb from a diode-pumped solid-state laser
; ; Keller, UrsulaWe present the first stabilization of the frequency comb offset from a diode-pumped gigahertz solid-state laser oscillator. No additional external amplification and/or compression of the output pulses is required. The laser is reliably modelocked using a SESAM and is based on a diode-pumped Yb:CALGO gain crystal. It generates 1.7-W average output power and pulse durations as short as 64 fs at a pulse repetition rate of 1 GHz. We generate an octave-spanning supercontinuum in a highly nonlinear fiber and use the standard ƒ-to-2ƒ carrier-envelope offset (CEO) frequency ƒCEO detection method. As a pump source, we use a reliable and cost-efficient commercial diode laser. Its multi-spatial-mode beam profile leads to a relatively broad frequency comb offset beat signal, which nevertheless can be phase-locked by feedback to its current. Using improved electronics, we reached a feedback-loop-bandwidth of up to 300 kHz. A combination of digital and analog electronics is used to achieve a tight phase-lock of ƒCEO to an external microwave reference with a low in-loop residual integrated phase-noise of 744 mrad in an integration bandwidth of [1 Hz, 5 MHz]. An analysis of the laser noise and response functions is presented which gives detailed insights into the CEO stabilization of this frequency comb. - PublicationAccès libreActive linewidth-narrowing of a mid-infrared quantum cascade laser without optical referenceWe report on a technique for frequency noise reduction and linewidth-narrowing of a distributed-feedback mid-IR quantum cascade laser (QCL) that does not involve any optical frequency reference. The voltage fluctuations across the QCL are sensed, amplified and fed back to the temperature of the QCL at a fast rate using a near-IR laser illuminating the top of the QCL chip. A locking bandwidth of 300 kHz and a reduction of the frequency noise power spectral density by a factor of 10 with respect to the free-running laser are achieved. From 2 MHz for the free-running QCL, the linewidth is narrowed below 700 kHz (10 ms observation time).
- PublicationAccès libreUltra-low noise microwave generation with a free-running optical frequency comb transfer oscillatorWe present ultra-low noise microwave synthesis by optical to radio-frequency (RF) division realized with a free-running or RF-locked optical frequency comb (OFC) acting as a transfer oscillator. The method does not require any optical lock of the OFC and circumvents the need for a high-bandwidth actuator. Instead, the OFC phase noise is electrically removed from a beat-note signal with an optical reference, leading to a broadband noise division. The phase noise of the ∼15  GHz RF signal generated in this proof-of-principle demonstration is limited by a shot-noise level below −150  dBc/Hz at high Fourier frequencies and by a measurement noise floor of −60  dBc/Hz at 1 Hz offset frequency when performing 1,100 cross-correlations. The method is attractive for high-repetition-rate OFCs that lead to a lower shot-noise, but are generally more difficult to tightly lock. It may also simplify the noise evaluation by enabling the generation of two or more distinct ultra-low noise RF signals from different optical references using a single OFC and their direct comparison to assess their individual noise.