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Silander, Isak
Publications (10 of 26) Show all publications
Silander, I., Hausmaninger, T., Zelan, M. & Axner, O. (2018). Gas modulation refractometry for high-precision assessment of pressure under non-temperature-stabilized conditions. Paper presented at AVS 64th International Symposium and Exhibition, OCT 29-NOV 03, 2017, Tampa, FL, USA. Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, 36(3), Article ID 03E105.
Open this publication in new window or tab >>Gas modulation refractometry for high-precision assessment of pressure under non-temperature-stabilized conditions
2018 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 36, no 3, article id 03E105Article in journal (Refereed) Published
Abstract [en]

The authors report on the realization of a novel methodology for refractometry-GAs modulation refractometry (GAMOR)-that decreases the influence of drifts in Fabry Perot cavity refractometry. The instrumentation is based on a dual Fabry-Perot cavity refractometer in which the beat frequency between the light fields locked to two different cavities, one measurement and one reference cavity, is measured. The GAMOR methodology comprises a process in which the measurement cavity sequentially is filled and evacuated while the reference cavity is constantly evacuated. By performing beat frequency measurements both before and after the finite-pressure measurement, zero point references are periodically created. This opens up for high precision refractometry under nontemperature-stabilized conditions. A first version of an instrumentation based on the GAMOR methodology has been realized and its basic performance has been scrutinized. The refractometer consists of a Zerodur cavity-block and tunable narrow linewidth fiber lasers operating within the C34 communication channel (i.e., around 1.55 μm) at which there are a multitude of fiber coupled off-the-shelf optical, electro-optic, and acousto-optic components. The system is fully computer controlled, which implies it can perform unattended gas assessments over any foreseeable length of time. When applied to a system with no active temperature stabilization, the GAMOR methodology has demonstrated a 3 orders of magnitude improvement of the precision with respect to conventional static detection. When referenced to a dead weight pressure scale the instrumentation has demonstrated assessment of pressures in the kilo-Pascal range (4303 and 7226 Pa) limited by white noise with standard deviations in the 3.2N-1/2-3.5N-1/2 mPa range, where N is the number of measurement cycles (each being 100 s long). For short measurement times (up to around 103 s), the system exhibits a (1σ) total relative precision of 0.7 (0.5) ppm for assessment of pressures in the 4 kPa region and 0.5 (0.4) ppm for pressures around 7 kPa, where the numbers in parentheses represent the part of the total noise that has been attributed to the refractometer. As long as the measurement procedure is performed over short time scales, the inherent properties of the GAMOR methodology allow for high precision assessments by the use of instrumentation that is not actively temperature stabilized or systems that are affected by outgassing or leaks. They also open up for a variety of applications within metrology; e.g., transfer of calibration and characterization of pressure gauges, including piston gauges.

National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:umu:diva-148832 (URN)10.1116/1.5022244 (DOI)000432372400005 ()2-s2.0-85045843634 (Scopus ID)
Conference
AVS 64th International Symposium and Exhibition, OCT 29-NOV 03, 2017, Tampa, FL, USA
Available from: 2018-06-13 Created: 2018-06-13 Last updated: 2018-06-13Bibliographically approved
Hausmaninger, T., Silander, I. & Axner, O. (2016). Doppler-broadened mid-infrared NICE-OHMS system based on an optical parametric oscillator. In: Laser Applications to Chemical, Security and Environmental Analysis: . Paper presented at Imaging and Applied Optics 2016, 25–28 July 2016, Heidelberg, Germany.
Open this publication in new window or tab >>Doppler-broadened mid-infrared NICE-OHMS system based on an optical parametric oscillator
2016 (English)In: Laser Applications to Chemical, Security and Environmental Analysis, 2016Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

An OPO-based NICE-OHMS instrument for trace gas detection addressing fundamental vibration transitions in the mid-IR (3.2-3.9 µm) range has been developed. It shows a detection sensitivity for CH4 of 2.4×10−10cm−1Hz−1∕2 (corresponding to low ppt concentrations).

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-153067 (URN)10.1364/LACSEA.2016.LT2G.2 (DOI)978-1-943580-15-6 (ISBN)
Conference
Imaging and Applied Optics 2016, 25–28 July 2016, Heidelberg, Germany
Available from: 2018-11-06 Created: 2018-11-06 Last updated: 2018-11-06Bibliographically approved
Ma, W., Silander, I., Hausmaninger, T. & Axner, O. (2016). Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition – I. Theoretical Description. Journal of Quantitative Spectroscopy and Radiative Transfer, 168, 217-244
Open this publication in new window or tab >>Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition – I. Theoretical Description
2016 (English)In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 168, p. 217-244Article in journal (Other academic) Published
Abstract [en]

Doppler-broadened (Db) noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) is conventionally described by an expression (here referred to as the CONV expression) that is restricted to the case when the single-pass absorbance, α0L, is much smaller than the empty cavity losses, π/F [here termed the conventional cavity-limited weak absorption (CCLWA) condition]. This limits the applicability of the technique, primarily its dynamic range and calibration capability. To remedy this, this work derives extended descriptions of Db NICEOHMS that are not restricted to the CCLWA condition. First, the general principles of Db NICEOHMS are scrutinized in some detail. Based solely upon a set of general assumptions, predominantly that it is appropriate to linearize the Beer–Lambert law, that the light is modulated to a triplet, and that the Pound–Drever–Hall sidebands are fully reflected, a general description of Db NICE-OHMS that is not limited to any specific restriction on α0L vs. π/F, here referred to as the FULL description, is derived. However, this description constitutes a set of equations to which no closed form solution has been found. Hence, it needs to be solved numerically (by iterations), which is inconvenient. To circumvent this, for the cases when α0Loπ/F but without the requirement that the stronger CCLWA condition needs to be fulfilled, a couple of simplified extended expressions that are expressible in closed analytical form, referred to as the extended locking and extended transmission description, ELET, and the extended locking and full transmission description, ELFT, have been derived. An analysis based on simulations validates the various descriptions and assesses to which extent they agree. It is shown that in the CCLWA limit, all extended descriptions revert to the CONV expression. The latter one deviates though from the extended ones for α0L around and above 0.1π/F. The two simplified extended descriptions agree with the FULL description for a larger range of α0L than the CONV expression, viz. for the ELET description for α0L up to 0.3π/F and for ELFT for α0L up to 0.6 or 1.0 π/F (depending on the mode of detection). It is then demonstrated that the conventional view of Db NICE-OHMS, which states that the out-of-phase and the in-phase signals can be referred to as a pure absorption and dispersion signal, respectively, breaks down when the CCLWA condition does not hold. In this case, the out-of-phase signal is additionally affected by the phase shifts of the laser components (i.e. dispersion) while the in-phase signal is also influenced by their attenuation. Access to new descriptions broadens considerably the dynamic range of Db NICE-OHMS and facilitates calibration using standard references samples, and thereby its applicability

Keywords
NICE-OHMS, Cavity enhanced spectroscopy, Dynamic range, Frequency modulation spectroscopy, Theoretical model
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-110271 (URN)10.1016/j.jqsrt.2015.09.007 (DOI)000366007000018 ()
Available from: 2015-10-19 Created: 2015-10-19 Last updated: 2018-11-06Bibliographically approved
Hausmaninger, T., Silander, I., Ma, W. & Axner, O. (2016). Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition – II: experimental verification. Journal of Quantitative Spectroscopy and Radiative Transfer, 168, 245-256
Open this publication in new window or tab >>Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition – II: experimental verification
2016 (English)In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 168, p. 245-256Article in journal (Refereed) Published
Abstract [en]

Doppler-broadened (Db) noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) is normally described by an expression, here termed the conventional (CONV) description, that is restricted to the conventional cavity-limited weak absorption condition (CCLWA), i.e. when the single pass absorbance is significantly smaller than the empty cavity losses, i.e. when α0L<<π/F. To describe NICE-OHMS signals beyond this limit two simplified extended descriptions (termed the extended locking and extended transmission description, ELET, and the extended locking and full transmission description, ELFT), which are assumed to be valid under the relaxed cavity-limited weak absorption condition (RCLWA), i.e. when α0L<π/Fα0L<π/F, and a full description (denoted FULL), presumed to be valid also when the α0L<π/Fα0L<π/F condition does not hold, have recently been derived in an accompanying work (Ma W, et al. Doppler-broadened NICE-OHMS beyond the cavity-limited weak absorption condition - I. Theoretical Description. J Quant Spectrosc Radiat Transfer, 2015, http://dx.doi.org/10.1016/j.jqsrt.2015.09.007, this issue). The present work constitutes an experimental verification and assessment of the validity of these, performed in the Doppler limit for a set of Fα0L/πFα0L/π values (up to 3.5); it is shown under which conditions the various descriptions are valid. It is concluded that for samples with Fα0L/πFα0L/π up to 0.01, all descriptions replicate the data well. It is shown that the CONV description is adequate and provides accurate assessments of the signal strength (and thereby the analyte concentration) up to Fα0L/πFα0L/π of around 0.1, while the ELET is accurate for Fα0L/πFα0L/π up to around 0.3. The ELFT description mimics the Db NICE-OHMS signal well for Fα0L/πFα0L/π up to around unity, while the FULL description is adequate for all Fα0L/πFα0L/π values investigated. Access to these descriptions both increases considerably the dynamic range of the technique and facilitates calibration using certified reference gases, which thereby significantly broadens the applicability of the Db NICE-OHMS technique.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
NICE OHMS, Frequency modulation spectroscopy, Cavity enhanced spect, Experimental verification
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-110273 (URN)10.1016/j.jqsrt.2015.09.008 (DOI)000366007000019 ()
Available from: 2015-10-19 Created: 2015-10-19 Last updated: 2018-11-06Bibliographically approved
Silander, I. (2015). Cavity enhanced optical sensing. (Doctoral dissertation). Umeå: Umeå universitet
Open this publication in new window or tab >>Cavity enhanced optical sensing
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Kavitetsförstärkt optisk detektion
Abstract [en]

An optical cavity comprises a set of mirrors between which light can be reflected a number of times. The selectivity and stability of optical cavities make them extremely useful as frequency references or discri­mi­nators. With light coupled into the cavity, a sample placed inside a cavity will experience a significantly increased interaction length. Hence, they can be used also as amplifiers for sensing purposes. In the field of laser spectroscopy, some of the most sensitive techniques are therefore built upon optical cavities. In this work optical cavities are used to measure properties of gas samples, i.e. absorption, dispersion, and refractivity, with unprecedented precision.

The most sensitive detection technique of all, Doppler-broadened noise-immune cavity enhanced optical heterodyne molecular spectrometry (Db NICE-OHMS), has in this work been developed to an ultra-sensitive spectroscopic technique with unprecedented detection sensitivity. By identifying limiting factors, realizing new experimental setups, and deter­mining optimal detection conditions, the sensitivity of the technique has been improved several orders of magnitude, from 8 × 10-11 to 9 × 10-14 cm-1. The pressure interval in which NICE-OHMS can be applied has been extended by deri­vation and verification of dispersions equations for so-called Dicke narrowing and speed dependent broadening effects. The theoretical description of NICE-OHMS has been expanded through the development of a formalism that can be applied to the situations when the cavity absorption cannot be considered to be small, which has expanded the dynamic range of the technique. In order to enable analysis of a large number of molecules at their most sensitive transitions (mainly their funda­mental CH vibrational transitions) NICE-OHMS instrumentation has also been developed for measurements in the mid-infrared (MIR) region. While it has been difficult to realize this in the past due to a lack of optical modulators in the MIR range, the system has been based on an optical para­metric oscillator, which can be modulated in the near-infrared (NIR) range.

As the index of refraction can be related to density, it is possible to retrieve gas density from measurements of the index of refraction. Two such instru­men­tations have been realized. The first one is based on a laser locked to a measure­ment cavity whose frequency is measured by compassion with an optical frequency comb. The second one is based on two lasers locked to a dual-cavity (i.e. one reference and one measurement cavity). By these methods changes in gas density down to 1 × 10-9 kg/m3 can be detected.

All instrumentations presented in this work have pushed forward the limits of what previously has been considered measurable. The knowledge acquired will be of great use for future ultrasensitive cavity-based detection methods.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2015. p. 124
Keywords
Optical resonators, Fiber Laser, Parametric oscillators, Optical frequency comb, Infrared, Spectroscopy heterodyne, Spectroscopy molecular, Absorption, Dispersion, Lineshapes, Optical standards and testing, Refractivety measurements
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-110278 (URN)978-91-7601-338-0 (ISBN)
Public defence
2015-11-13, KBC-huset, KB3A9 (lilla hörsalen i KBC-huset), Umeå universitet, Umeå, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Research CouncilThe Kempe Foundations
Available from: 2015-10-23 Created: 2015-10-19 Last updated: 2018-06-07Bibliographically approved
Silander, I., Hausmaninger, T., Ma, W., Harren, F. J. M. & Axner, O. (2015). Doppler-broadened mid-infrared noise-immune cavity-enhanced optical heterodyne molecular spectrometry based on an optical parametric oscillator for trace gas detection. Optics Letters, 40(4), 439-442
Open this publication in new window or tab >>Doppler-broadened mid-infrared noise-immune cavity-enhanced optical heterodyne molecular spectrometry based on an optical parametric oscillator for trace gas detection
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2015 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 40, no 4, p. 439-442Article in journal (Refereed) Published
Abstract [en]

An optical parametric oscillator based Doppler-broadened (Db) noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) system suitable for addressing fundamental vibrational transitions in the 3.2-3.9 mu m mid-infrared (MIR) region has been realized. An Allan-Werle analysis provides a detection sensitivity of methane of 1.5 x 10-9 cm(-1) with a 20 s integration time, which corresponds to 90 ppt of CH4 if detected at the strongest transition addressed at 40 Torr. This supersedes that of previous Db MIR NICE-OHMS demonstrations and suggests that the technique can be suitable for detection of both the environmentally important (CH4)-C-13 and CH3D isotopologues. It also opens up for detection of many other molecular species at ppt and sub-ppt concentration levels.

National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-101400 (URN)10.1364/OL.40.000439 (DOI)000349848400001 ()25680119 (PubMedID)
Available from: 2015-07-02 Created: 2015-03-30 Last updated: 2018-11-06Bibliographically approved
Silander, I., Hausmaninger, T., Ma, W., Ehlers, P. & Axner, O. (2015). Doppler-broadened noise-immune cavity-enhanced optical heterodyne molecular spectrometry down to 4 x 10-13 cm-1 Hz-1/2: implementation of a 50,000 finesse cavity. Optics Letters, 40(9), 2004-2007
Open this publication in new window or tab >>Doppler-broadened noise-immune cavity-enhanced optical heterodyne molecular spectrometry down to 4 x 10-13 cm-1 Hz-1/2: implementation of a 50,000 finesse cavity
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2015 (English)In: Optics Letters, ISSN 0146-9592, E-ISSN 1539-4794, Vol. 40, no 9, p. 2004-2007Article in journal (Refereed) Published
Abstract [en]

We report on the realization of a Doppler-broadened noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) instrumentation based on a high-finesse (50,000) cavity with a detection sensitivity of 4 x 10(-13) cm(-1) Hz(-1/2). For the P-e(11) transition targeted at 1.5316 mu m, this corresponds to a C2H2 concentration of 240 ppq (parts-per-quadrillion) detected at 100 Torr. The setup was originally affected by recurrent dips in the cavity transmission, which were attributed to excitation of high-order transverse mode by scattering from the mirrors. The effect of these was reduced by insertion of a small pinhole in the cavity.

Place, publisher, year, edition, pages
Optical Society of America, 2015
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-106284 (URN)10.1364/OL.40.002004 (DOI)000353924600031 ()25927769 (PubMedID)
Available from: 2015-07-10 Created: 2015-07-09 Last updated: 2018-06-07Bibliographically approved
Silander, I., Hausmaninger, T. & Axner, O. (2015). Model for in-coupling of etalons into signal strengths extracted from spectral line shape fitting and methodology for predicting the optimum scanning range: demonstration of Doppler-broadened, noise-immune, cavity-enhanced optical heterodyne molecular spectroscopy down to 9  ×  10−14 cm−1. Journal of the Optical Society of America. B, Optical physics, 32(10), 2104-2114
Open this publication in new window or tab >>Model for in-coupling of etalons into signal strengths extracted from spectral line shape fitting and methodology for predicting the optimum scanning range: demonstration of Doppler-broadened, noise-immune, cavity-enhanced optical heterodyne molecular spectroscopy down to 9  ×  10−14 cm−1
2015 (English)In: Journal of the Optical Society of America. B, Optical physics, ISSN 0740-3224, E-ISSN 1520-8540, Vol. 32, no 10, p. 2104-2114Article in journal (Refereed) Published
Abstract [en]

Expressions for the in-coupling of white noise and etalons into fitted signal strengths are derived. These show that the amount of noise picked up is affected by the scanning range. A methodology for finding the optimum scanning range from a single set of measurements has been developed. This was used to estimate the optimum conditions of a noise-immune, cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) setup. The methodology was validated by measurements. This resulted in a spectral noise equivalent absorption per unit length of 2.6 × 10−13 cm−1 Hz−1∕2 and a minimum Allan deviation of 9 × 10−14 cm−1 at 30 s, which are, to our knowledge, the lowest reported for Doppler-broadened NICE-OHMS

Place, publisher, year, edition, pages
Optical Society of America, 2015
Keywords
Absorption, Spectroscopy - heterodyne, Spectroscopy - modulation, Spectroscopy - molecular
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-110081 (URN)10.1364/JOSAB.32.002104 (DOI)000367235700012 ()
Available from: 2015-10-15 Created: 2015-10-15 Last updated: 2018-06-07Bibliographically approved
Hausmaninger, T., Silander, I. & Axner, O. (2015). Narrowing of the linewidth of an optical parametric oscillator by an acousto-optic modulator for the realization of mid-IR noise-immune cavity-enhanced optical heterodyne molecular spectrometry down to 10(-10) cm(-1) Hz(-1/2). Optics Express, 23(26), 33641-33655, Article ID UNSP 252446.
Open this publication in new window or tab >>Narrowing of the linewidth of an optical parametric oscillator by an acousto-optic modulator for the realization of mid-IR noise-immune cavity-enhanced optical heterodyne molecular spectrometry down to 10(-10) cm(-1) Hz(-1/2)
2015 (English)In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 23, no 26, p. 33641-33655, article id UNSP 252446Article in journal (Refereed) Published
Abstract [en]

The linewidth of a singly resonant optical parametric oscillator (OPO) has been narrowed with respect to an external cavity by the use of an acousto-optic modulator (AOM). This made possible an improvement of the sensitivity of a previously realized OPO-based noise-immune cavity-enhanced optical heterodyne molecular spectrometry instrument for the 3.2 - 3.9 mu m mid-infrared region by one order of magnitude. The resulting system shows a detection sensitivity for methane of 2.4 x 10(-10) cm(-1) Hz(-1/2) and 1.3 x 10(-10) cm(-1) at 20 s, which allows for detection of both the environmentally important (CH4)-C-13 and CH3D isotopologues in atmospheric samples. (C) 2015 Optical Society of America

Keywords
VOE RG, 1984, PHYSICAL REVIEW A, V30, P2827 ittaker K. E., 2012, APPLIED PHYSICS B-LASERS AND OPTICS, V109, P333 Cartt A. D., 2015, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM
National Category
Physical Sciences
Identifiers
urn:nbn:se:umu:diva-116097 (URN)10.1364/OE.23.033641 (DOI)000368004600074 ()
Available from: 2016-02-08 Created: 2016-02-08 Last updated: 2018-11-06Bibliographically approved
Ehlers, P., Wang, J., Silander, I. & Axner, O. (2014). Doppler broadened NICE-OHMS beyond the triplet formalism: assessment of optimum modulation index. Journal of the Optical Society of America. B, Optical physics, 31(7), 1499-1507
Open this publication in new window or tab >>Doppler broadened NICE-OHMS beyond the triplet formalism: assessment of optimum modulation index
2014 (English)In: Journal of the Optical Society of America. B, Optical physics, ISSN 0740-3224, E-ISSN 1520-8540, Vol. 31, no 7, p. 1499-1507Article in journal (Refereed) Published
Abstract [en]

The dependence of Doppler broadened noise-immune cavity-enhanced optical heterodyne molecular spectrometry (NICE-OHMS) on the modulation index, beta, has been investigated experimentally on C2H2 and CO2, both in the absence and the presence of optical saturation. It is shown that the maximum signals are obtained for beta that produce more than one pair of sidebands: in the Doppler limit and for the prevailing conditions (unsaturated transition and the pertinent modulation frequency and Doppler widths) around 1 and 1.4 for the dispersion and absorption detection phases, respectively. The results verify predictions given in an accompanying work. It is also shown that there is no substantial broadening of the NICE-OHMS signal for beta < 1. The use of beta of unity has yielded a Db-NICE-OHMS detection sensitivity of 4.9 x 10(-12) cm(-1) Hz(-1/2), which is the lowest (best) value so far achieved for NICE-OHMS based on a tunable laser. The number of sidebands that needs to be included in fits of the line-shape function to obtain good accuracy has been assessed. It is concluded that it is enough to consider three pairs of sidebands whenever the systematic errors in a concentration assessment should be below 1% when beta < 2 are used and <1 parts per thousand for beta < 1.5.

Place, publisher, year, edition, pages
Optical Society of America, 2014
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-91852 (URN)10.1364/JOSAB.31.001499 (DOI)000338931700013 ()
Note

Ingår i Patrick Ehlers doktorsavhandling som delarbete nr XI med titeln: NICE-OHMS beyond the triplet formalism: assessment of the optimum modulation index.

Available from: 2014-08-26 Created: 2014-08-18 Last updated: 2018-06-07Bibliographically approved
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