101 research outputs found
Impact of dispersion on amplitude and frequency noise in a Yb-fiber laser comb
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 100Ă— 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
High-power broadband laser source tunable from 3.0 um to 4.4 um based on a femtosecond Yb:fiber oscillator
We describe a tunable broadband mid-infrared laser source based on
difference-frequency mixing of a 100 MHz femtosecond Yb:fiber laser oscillator
and a Raman-shifted soliton generated with the same laser. The resulting light
is tunable over 3.0 um to 4.4 um, with a FWHM bandwidth of 170 nm and maximum
average output power up to 125 mW. The noise and coherence properties of this
source are also investigated and described.Comment: To appear in Optics Letter
Sub-100-as timing jitter optical pulse trains from mode-locked Er-fiber lasers
We demonstrate sub-100-attosecond timing jitter optical pulse trains
generated from free-running, 77.6-MHz repetition-rate, mode-locked Er-fiber
lasers. At -0.002(\pm0.001) ps2 net cavity dispersion, the rms timing jitter is
70 as (224 as) integrated from 10 kHz (1 kHz) to 38.8 MHz offset frequency,
when measured by a 24-as-resolution balanced optical cross-correlator. To our
knowledge, this result corresponds to the lowest rms timing jitter measured
from any mode-locked fiber lasers so far. The measured result also agrees
fairly well with the Namiki-Haus analytic model of quantum-limited timing
jitter in stretched-pulse fiber lasers.Comment: 4 pages, 2 figures, to appear in Optics Letter
The Impact of Dispersion on Amplitude and Frequency Noise in a Yb-fiber Laser Comb
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
Modeling long-range cross-correlations in two-component ARFIMA and FIARCH processes
We investigate how simultaneously recorded long-range power-law correlated
multi-variate signals cross-correlate. To this end we introduce a two-component
ARFIMA stochastic process and a two-component FIARCH process to generate
coupled fractal signals with long-range power-law correlations which are at the
same time long-range cross-correlated. We study how the degree of
cross-correlations between these signals depends on the scaling exponents
characterizing the fractal correlations in each signal and on the coupling
between the signals. Our findings have relevance when studying parallel outputs
of multiple-component of physical, physiological and social systems.Comment: 8 pages, 5 figures, elsart.cl
Mid-infrared VIPA Spectrometer for Rapid and Broadband Trace Gas Detection
We present and characterize a 2-D imaging spectrometer based on a
virtually-imaged phased array (VIPA) disperser for rapid, high-resolution
molecular detection using mid-infrared (MIR) frequency combs at 3.1 and 3.8 \mu
m. We demonstrate detection of CH4 at 3.1 \mu m with >3750 resolution elements
spanning >80 nm with ~600 MHz resolution in a <10 \mu s acquisition time. In
addition to broadband detection, rapid, time-resolved single-image detection is
demonstrated by capturing dynamic concentration changes of CH4 at a rate of
~375 frames per second. Changes in absorption above the noise floor of 5\times
10-4 are readily detected on the millisecond time scale, leading to important
future applications such as real time monitoring of trace gas concentrations
and detection of reactive intermediates
Holographic optical tweezers combined with back-focal-plane displacement detection
A major problem with holographic optical tweezers (HOTs) is their incompatibility with laser-based position detection methods, such as back-focal-plane interferometry (BFPI). The alternatives generally used with HOTs, like high-speed video tracking, do not offer the same spatial and temporal bandwidths. This has limited the use of this technique in precise quantitative experiments. In this paper, we present an optical trap design that combines digital holography and back-focal-plane displacement detection. We show that, with a particularly simple setup, it is possible to generate a set of multiple holographic traps and an additional static non-holographic trap with orthogonal polarizations and that they can be, therefore, easily separated for measuring positions and forces with the high positional and temporal resolutions of laser-based detection. We prove that measurements from both polarizations contain less than 1% crosstalk and that traps in our setup are harmonic within the typical range. We further tested the instrument in a DNA stretching experiment and we discuss an interesting property of this configuration: the small drift of the differential signal between traps
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