Nonlinear transmission spectroscopy with dual frequency combs

We show how two frequency combs $\mathcal{E}_1$, $\mathcal{E}_2$ can be used to measure single-photon, two-photon absorption (TPA), and Raman resonances in a molecule with three electronic bands, by detecting the radio frequency modulation of the nonlinear transmission signal. Some peaks are independent of the carrier frequency of the comb and others shift with that frequency and have a width close to the comb width. TPA and Raman resonances independent of the carrier frequency are selected by measuring the transmission signal $\sim\mathcal{E}_1^2 \mathcal{E}_2^2$ and the single-photon resonances are selected by measuring the transmission signal $\sim\mathcal{E}_1^3\mathcal{E}_2$. Sinusoidal spectral phase shaping strongly affects the TPA, but not the Raman resonances.Comment: 13 pages, 11 Figure

Extreme-Environment Silicon-Carbide (SiC) Wireless Sensor Suite

Phase II objectives: Develop an integrated silicon-carbide wireless sensor suite capable of in situ measurements of critical characteristics of NTP engine; Compose silicon-carbide wireless sensor suite of: Extreme-environment sensors center, Dedicated high-temperature (450 deg C) silicon-carbide electronics that provide power and signal conditioning capabilities as well as radio frequency modulation and wireless data transmission capabilities center, An onboard energy harvesting system as a power source

Double-modulation electro-optic sampling for pump-and-probe ultrafast correlation measurements

Journal ArticleWe describe a novel electro-optic double-modulation (DM) sampling technique for ultrafast transient spectroscopy, which is characterized by a superior signal-to-noise ratio compared to that of a regular single-modulation technique. DM is achieved by a combined effect of a radio-frequency modulation, which eliminates most of the low-frequency noise, and an audio-frequency modulation, which makes use of a high-performance, low-frequency lock-in amplifier. The DM sensitivity is comparable to that of the more sophisticated schemes involving electrical mixing and the A - B noise reduction method. We show that the DM technique offers superior performance in two-beam transient pump-and-probe correlation measurements compared to the regular single frequency modulation technique and is an ideal scheme for three-beam picosecond correlation measurements

Surface emitting ring quantum cascade lasers for chemical sensing

Documento escrito por un elevado número de autores/as, solo se referencia el/la que aparece en primer lugar y los autores pertenecientes a la UC3MWe review recent advances in chemical sensing applications based on surface emitting ring quantum cascade lasers (QCLs). Such lasers can be implemented in monolithically integrated on-chip laser/detector devices forming compact gas sensors, which are based on direct absorption spectroscopy according to the Beer-Lambert law. Furthermore, we present experimental results on radio frequency modulation up to 150 MHz of surface emitting ring QCLs. This technique provides detailed insight into the modulation characteristics of such lasers. The gained knowledge facilitates the utilization of ring QCLs in combination with spectroscopic techniques, such as heterodyne phase-sensitive dispersion spectroscopy for gas detection and analysis

Experimental demonstration of continuous variable purification of squeezed states

We report on the first experimental demonstration of purification of nonclassical continuous variable states. The protocol uses two copies of phase-diffused states overlapped on a beam splitter and provides Gaussified, less mixed states with the degree of squeezing improved. The protocol uses only linear optical devices such as beam splitters and homodyne detection, thereby proving these optical elements can be used for successful purification of this type of state decoherence which occurs in optical transmission channels

Fiber optic sensing system

A fiber optic interferometer utilizes a low coherence light emitting diode (LED) laser as a light source which is filtered and driven at two RF frequencies, high and low, that are specific to the initial length of the resonator chamber. A displacement of a reflecting mirror changes the length traveled by the nonreferencing signal. The low frequency light undergoes destructive interference which reduces the average intensity of the wave while the high frequency light undergoes constructive interference which increases the average intensity of the wave. The ratio of these two intensity measurements is proportional to the displacement incurred

Inversion of the Bloch transform in magnetic resonance imaging using asymmetric two-component inverse scattering

In magnetic resonance imaging, the relation between the radio-frequency modulation of the magnetic field and the desired final magnetisation state is called the Bloch transform. Selective excitation then amounts to inverting this transform, which is highly nonlinear. Previous attempts to formulate this problem as an inverse scattering problem have restricted attention to solutions using reflectionless potentials. The author uses fast numerical algorithms for inverse scattering problems to obtain a much larger set of solutions. Numerical examples are included.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49094/2/ipv6i1p133.pd