The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Giorgio Santarelli - One of the best experts on this subject based on the ideXlab platform.
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an agile laser with ultra low Frequency Noise and high sweep linearity
Optics Express, 2010Co-Authors: Haifeng Jiang, A Clairon, Fabien Kefelian, P Lemonde, Giorgio SantarelliAbstract:We report on a fiber-stabilized agile laser with ultra-low Frequency Noise. The Frequency Noise power spectral density is comparable to that of an ultra-stable cavity stabilized laser at Fourier frequencies higher than 30 Hz. When it is chirped at a constant rate of ~ 40 MHz/s, the max non-linearity Frequency error is about 50 Hz peak-to-peak over more than 600 MHz tuning range. The Rayleigh backscattering is found to be a significant Frequency Noise source dependent on fiber length, chirping rate and the power imbalance of the interferometer arms. We analyze this effect both theoretically and experimentally and put forward techniques to reduce this Noise contribution.
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ultralow Frequency Noise stabilization of a laser by locking to an optical fiber delay line
Optics Letters, 2009Co-Authors: Fabien Kefelian, Haifeng Jiang, P Lemonde, Giorgio SantarelliAbstract:We report the Frequency stabilization of an erbium-doped fiber distributed-feedback laser using an all-fiber-based Michelson interferometer of large arm imbalance. The interferometer uses a 1 km SMF-28 optical fiber spool and an acousto-optic modulator allowing heterodyne detection. The Frequency-Noise power spectral density is reduced by more than 40 dB for Fourier frequencies ranging from 1 Hz to 10 kHz, corresponding to a level well below 1 Hz2/Hz over the entire range; it reaches 10(-2) Hz2/Hz at 1 kHz. Between 40 Hz and 30 kHz, the Frequency Noise is shown to be comparable to the one obtained by Pound-Drever-Hall locking to a high-finesse Fabry-Perot cavity. Locking to a fiber delay line could consequently represent a reliable, simple, and compact alternative to cavity stabilization for short-term linewidth reduction.
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ultra low Frequency Noise laser by locking to an optical fiber delay line
arXiv: Instrumentation and Detectors, 2009Co-Authors: Fabien Kefelian, Haifeng Jiang, P Lemonde, Giorgio SantarelliAbstract:We report the Frequency stabilization of an erbium-doped fiber distributed-feedback laser using an all-fiber based Michelson interferometer of large arm imbalance. The interferometer uses a 1 km SMF-28 optical fiber spool and an acousto optic modulator allowing heterodyne detection. The Frequency Noise power spectral density is reduced by more than 40 dB for Fourier frequencies ranging from 1 Hz to 10 kHz, corresponding to a level well below 1 Hz^2/Hz over the whole range. It reaches 10^{-2} Hz^2/Hz at 1 kHz. Between 40 Hz and 30 kHz, the Frequency Noise is shown to be comparable to the one obtained by Pound-Drever-Hall locking to a high finesse Fabry-Perot cavity. Locking to a fiber delay line could consequently represent a reliable, simple and compact alternative to cavity stabilization for short term linewidth reduction.
Daniel Hofstetter - One of the best experts on this subject based on the ideXlab platform.
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temperature dependence of the Frequency Noise in a mid ir dfb quantum cascade laser from cryogenic to room temperature
Optics Express, 2012Co-Authors: Lionel Tombez, Stéphane Schilt, Joab Di Francesco, P Thomann, Daniel HofstetterAbstract:We report on the measurement of the Frequency Noise power spectral density in a distributed feedback quantum cascade laser over a wide temperature range, from 128 K to 303 K. As a function of the device temperature, we show that the Frequency Noise behavior is characterized by two different regimes separated by a steep transition at ≈200 K. While the Frequency Noise is nearly unchanged above 200 K, it drastically increases at lower temperature with an exponential dependence. We also show that this increase is entirely induced by current Noise intrinsic to the device. In contrast to earlier publications, a single laser is used here in a wide temperature range allowing the direct assessment of the temperature dependence of the Frequency Noise.
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Frequency Noise of free running 4 6 μm distributed feedback quantum cascade lasers near room temperature
Optics Letters, 2011Co-Authors: Lionel Tombez, Stéphane Schilt, P Thomann, J Di Francesco, G Di Domenico, Jerome Faist, Daniel HofstetterAbstract:The Frequency Noise properties of commercial distributed feedback quantum cascade lasers emitting in the 4.6 μm range and operated in cw mode near room temperature (277 K) are presented. The measured Frequency Noise power spectral density reveals a flicker Noise dropping down to the very low level of <100 Hz2/Hz at 10 MHz Fourier Frequency and is globally a factor of 100 lower than data recently reported for a similar laser operated at cryogenic temperature. This makes our laser a good candidate for the realization of a mid-IR ultranarrow linewidth reference.
Scott A Diddams - One of the best experts on this subject based on the ideXlab platform.
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impact of dispersion on amplitude and Frequency Noise in a yb fiber laser comb
Optics Letters, 2011Co-Authors: Lora Nugentglandorf, Todd A Johnson, Yohei Kobayashi, Scott A DiddamsAbstract:We describe a Yb-fiber-based laser comb, with a focus on the relationship between the net-cavity dispersion and Frequency Noise on the comb. While tuning the net-cavity dispersion from anomalous to normal, we measure the relative intensity Noise, offset Frequency (fCEO) linewidth, and the resulting Frequency Noise spectrum on the fCEO. We find that the laser operating at zero net-cavity dispersion has many advantages, including an approximately 100× reduction in free-running fCEO linewidth and Frequency Noise power spectral density when compared to the normal-dispersion regime. At the zero-dispersion point, we demonstrate a phase-locked fCEO beat with low residual Noise.
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the impact of dispersion on amplitude and Frequency Noise in a yb fiber laser comb
arXiv: Optics, 2011Co-Authors: Lora Nugentglandorf, Todd A Johnson, Yohei Kobayashi, Scott A DiddamsAbstract:We describe a Yb-fiber based laser comb, with a focus on the relationship between net-cavity dispersion and the Frequency Noise on the comb. While tuning the net cavity dispersion from anomalous to normal, we measure the amplitude Noise (RIN), offset Frequency (f_CEO) linewidth, and the resulting Frequency Noise spectrum on f_CEO. We find that the laser operating at zero net-cavity dispersion has many advantages, including an approximately 100x reduction in free-running f_CEO linewidth and Frequency Noise power spectral density between laser operation at normal and zero dispersion. In this latter regime, we demonstrate a phase-locked f_CEO beat with low residual Noise.
R Wordenweber - One of the best experts on this subject based on the ideXlab platform.
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low Frequency Noise reduction in yba2cu3o7 δ superconducting quantum interference devices by antidots
Applied Physics Letters, 2000Co-Authors: P Selders, R WordenweberAbstract:It is demonstrated that the low-Frequency Noise due to vortex motion in high-temperature superconducting quantum interference devices (SQUIDs) in ambient magnetic fields can strongly be reduced by a simple arrangement of antidots patterned into the SQUID. Sputter-deposited YBa2Cu3O7−δ radio-Frequency SQUIDs (rf-SQUIDs) with step edge junctions are characterized before and after patterning of antidots in the vicinity of the Josephson junction. No deterioration of the rf-SQUIDs due to the introduction of the antidots can be detected. In contrary, the onset of the increase of the low-Frequency Noise in an applied magnetic field is shifted from 10 μT for the bare SQUID to 40 (field cooled) and 18 μT (zero-field cooled) for the rf-SQUIDs with antidots. The reduction of low-Frequency Noise in ambient field is explained by trapping of vortices by the antidots. The comparison of zero-field and field-cooled experiments demonstrates that flux penetrating the washer does not affect the low-Frequency Noise as long as...
Thomas J Silva - One of the best experts on this subject based on the ideXlab platform.
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nonwhite Frequency Noise in spin torque oscillators and its effect on spectral linewidth
Physical Review B, 2010Co-Authors: Mark W Kelle, Matthew R Pufall, William H Rippard, Thomas J SilvaAbstract:We measure the power spectral density of Frequency fluctuations in nanocontact spin torque oscillators over time scales up to 50 ms. We use a mixer to convert oscillator signals ranging from 10 GHz to 40 GHz into a band near 70 MHz before digitizing the time-domain waveform. We analyze the waveform using both zero crossing time stamps and a sliding Fourier transform, discuss the different limitations and advantages of these two methods, and combine them to obtain a Frequency Noise spectrum spanning more than five decades of Fourier Frequency $f$. For devices having a free layer consisting of either a single ${\text{Ni}}_{80}{\text{Fe}}_{20}$ layer or a Co/Ni multilayer we find a Frequency Noise spectrum that is white at large $f$ and varies as $1/f$ at small $f$. The crossover Frequency ranges from $\ensuremath{\approx}{10}^{4}$ Hz to $\ensuremath{\approx}{10}^{6}\text{ }\text{Hz}$ and the $1/f$ component is stronger in the multilayer devices. Through actual and simulated spectrum analyzer measurements, we show that $1/f$ Frequency Noise causes both broadening and a change in shape of the oscillator's spectral line as measurement time increases. Our results indicate that the long term stability of spin torque oscillators cannot be accurately predicted from models based on thermal (white) Noise sources.