Markus Sigrist - Academia.edu (original) (raw)

Papers by Markus Sigrist

Topics in Applied Physics, 2003

The availability of continuously tunable narrow-band laser sources emitting in the mid-infrared r... more The availability of continuously tunable narrow-band laser sources emitting in the mid-infrared region of the electromagnetic spectrum between 2.5 μm and 15 μm is important for a large variety of applications. One way to achieve both broad tunability and narrow linewidth is frequency conversion in a nonlinear optical material, in particular difference frequency generation (DFG). After a brief introduction to

Photons Plus Ultrasound: Imaging and Sensing 2005: The Sixth Conference on Biomedical Thermoacoustics, Optoacoustics, and Acousto-optics, 2005

In this paper, we present first results of a spectral characterisation of doping substances using... more In this paper, we present first results of a spectral characterisation of doping substances using a resonant optoacoustic cell and a Nd:YAG laser pumped optical parametric generation (OPG) laser source in the mid-infrared wavelength range between 3.0 and 4.0 µm with periodically poled LiNbO3 as nonlinear medium for the frequency conversion. Single spectra covering a wavelength range of about 220

2008 Conference on Lasers and Electro-Optics, 2008

Following the ingestion of only 5 mL D2O, an infrared laser spectrometer determines the D/H isoto... more Following the ingestion of only 5 mL D2O, an infrared laser spectrometer determines the D/H isotope ratio increase in exhaled water vapor for the first time. No preliminary breath sample preparation is required.

A fiber-coupled difference frequency generation laser spectrometer for measuring isotopic composi... more A fiber-coupled difference frequency generation laser spectrometer for measuring isotopic compositions of N2O at trace concentrations is presented. Using wavelength modulation 90/00 precision at 100 ppm is achieved. The accuracy is demonstrated with enriched samples.

Novel Optical Instrumentation for Biomedical Applications II, 2005

There is a great need for a low cost and sensitive method to measure infrared spectra of solid or... more There is a great need for a low cost and sensitive method to measure infrared spectra of solid organic compounds in the gas phase. To record such spectra, we propose an optical parametric generator-based photoacoustic spectrometer, which emits in the mid-infrared fingerprint region between 3 and 4 microns. In this system, the sample is heated in a vessel before entering

Multi-component high-sensitivity trace gas analysis with mid-infrared tunable laser sources and d... more Multi-component high-sensitivity trace gas analysis with mid-infrared tunable laser sources and different detection schemes is discussed. The essential features of available midinfrared lasers are briefly outlined and the advantages and drawbacks of commonly used detection methods are presented. Selected applications from our own laboratory ranging from traffic emission, environmental and industrial monitoring to doping agents and medical diagnosis are briefly reviewed. The main topic of this paper is devoted to a difference frequency source employed in isotope ratio determinations. As example, measurements on isotopomers of CO, CO2 and N2O are presented. Keywords: Trace gases; infrared spectroscopy; isotopomers; difference frequency generation.

CLEO: 2013, 2013

ABSTRACT We demonstrate multi-color DFB QCLs with separated electrical pumping for independent si... more ABSTRACT We demonstrate multi-color DFB QCLs with separated electrical pumping for independent single-mode emission of several wavelengths from the same ridge. This will be implemented in our mid-infrared spectroscopy sensors for gases (CO2) and liquids (cocaine).

Quantum Sensing and Nanophotonic Devices VII, 2010

ABSTRACT Laser-spectroscopic applications in medicine increase in importance. We present two medi... more ABSTRACT Laser-spectroscopic applications in medicine increase in importance. We present two medical applications of laser-based analyses of trace gases. The analysis of exhaled breath concerns the determination of the D/H isotope ratio after intake of a small amount of heavy water. The D/H isotope ratio can be used to deduce the total body water weight and lays the foundation for many other laser-based clinical applications. An elevated D/H ratio could be monitored in breath samples up to 30 days after ingestion of only 5 ml of D/sub 2/O. A second example concerns the analysis of surgical smoke produced in minimally invasive laparoscopic surgery with electroknives. The quantitative determination of harmless and hazardous compounds down to the ppm level is demonstrated. A specific example is the presence of sevoflurane at concentrations of 80 to 300 ppm, an anesthetic, which to our knowledge is measured for the first time in an abdominal cavity.

Springer Handbook of Lasers and Optics, 2007

Abstract This chapter describes lasers and other sources of coherent light that operate in a wide... more Abstract This chapter describes lasers and other sources of coherent light that operate in a wide wavelength range. First, the general principles for the generation of coherent continuous-wave and pulsed radiation are treated including the interaction of radiation ...

Sensors and Actuators B: Chemical, 2008

Review of Scientific Instruments, 2007

In absorption spectroscopy, infrared spectra of heated gases or condensed samples in the vapor ph... more In absorption spectroscopy, infrared spectra of heated gases or condensed samples in the vapor phase are usually recorded with a single pass heated gas cell. This device exhibits two orders of magnitude lower sensitivity than the high-temperature multipass cell presented in this article. Our device is a novel type of compact long path absorption cell that can withstand aggressive chemicals in addition to temperatures up to 723 K. The construction of the cell and its technical features are described in detail, paying special attention to the mechanisms that compensate for thermal expansion and that allow the user to vary the optical path length under any thermal or vacuum condition. The cell may be used with a laser source or implemented within a Fourier transform infrared spectrometer. Its design is compatible with optical arrangements using astigmatic mirrors or spherical mirrors in a Herriott configuration. Here we implement a homebuilt Herriott-type cell with a total optical path length of up to 35 m. In order to demonstrate the feasibility of the cell, methane and water vapor absorption lines showing dissimilar temperature effects on line intensity were recorded with the help of a mid-infrared laser source tunable between 3 and 4 microm. Emphasis is put on lines that are too weak to be recorded with a single pass cell.

Review of Scientific Instruments, 1991

Abstract A novel design of a windowless resonant photoacoustic chamber with open acoustic filters... more Abstract A novel design of a windowless resonant photoacoustic chamber with open acoustic filters and an electronic resonance locking circuitry is presented. The acoustic behavior of the cell and preliminary measurements on a certified gas mixture with a CO 2 ...

Photochemical & Photobiological Sciences, 2003

Ammonia and ethene are pollutants which are arousing concern as regards their environmental impac... more Ammonia and ethene are pollutants which are arousing concern as regards their environmental impact, e.g. as greenhouse gases. Road traffic is an increasingly important emission source for these gases. As part of an atmospheric pollution measurement campaign, we performed in situ measurements of NH3, C2H4 and CO2 concentrations at the mouth of a freeway tunnel with a time resolution of 1 min using a mobile laser-based photoacoustic system. Measurements were performed over a period of 5 weeks. In good temporal correlation with traffic counts, we observed peak concentrations of >600 ppb (>1200 ppb for Friday afternoon peaks) for NH3, of up to 400 ppb for C2H4 and >2000 ppm for CO2. Preliminary comparisons with previous measurements at the same location indicate a considerable increase in ammonia and CO2 peak concentrations (greater than the increase in traffic over the same period) and a less pronounced increase in C2H4 concentrations.

Optics Letters, 1999

We present a novel compact pulsed laser spectrometer based on difference-frequency mixing of a cw... more We present a novel compact pulsed laser spectrometer based on difference-frequency mixing of a cw tunable external-cavity diode laser (795-825 nm) and a pulsed Nd:YAG laser (1064 nm) in bulk LiNbO(3) . The pulsed mid-IR source is continuously tunable from 3.16 to 3.67microm and exhibits a linewidth of only 154 MHz, a peak power of approximately 50microW , and a pulse duration of 6 ns at a 6.5-kHz repetition rate. Spectra of methane in room air and formaldehyde have been recorded at room-temperature operation in a multipass cell with deduced detection limits of 10 and 40 parts in 10(9) , respectively.

Optics Letters, 2009

Following the ingestion of only 5.1 mL of D2O, a mid-infrared laser spectrometer determines the D... more Following the ingestion of only 5.1 mL of D2O, a mid-infrared laser spectrometer determines the D/H isotope ratio increase in exhaled water vapor for the first time, to the best of our knowledge. This increase is still detectable several weeks after the heavy water intake. Collected breath samples are directly transferred into a high-temperature multipass cell operated at 373 K. No breath sample preparation is required. Aside from the capability to hinder unwanted condensation, measurements at elevated temperatures offer other advantages such as a lower temperature dependence of the delta value or the possibility to vary the intensity of absorption lines. We lay the foundation for many laser-based clinical applications. As an example, we measure a total body water weight of 55.2%+/-1.8% with respect to the total body weight, in agreement with the normal value of the male population.