共查询到20条相似文献,搜索用时 31 毫秒
1.
Stable, low noise, infrared squeezed state tight at 1064 nm is generated by utilizing optical parametric down-conversion (OPDC)
technique based on periodically poled KTiOPO4 in a optical parametric amplifier (OPA) resonator. A non-classical noise reduction of 2.58 dB below the shot noise is observed
through balanced homodyne detection. The squeezed state light is used to set up an imaging system for high-resolution imaging,
and it is found that the resolution of image based on the amplitude-squeezed light is 1.26 times larger than that of infrared
coherent light under the same intensity. The experimental results indicate that squeezed light is an important non-classical
light, which can overcome the coherent laser shot-noise, the classical diffraction limit and limit of quantum noise. 相似文献
2.
Sagnac effect enhancement can improve optical gyro precision. For a certain input intensity, we suggest that the other input port of beam splitter(BS) should be fed with some quantum light to break through shot noise limit(SNL) to improve Sagnac effect without increasing radiation-pressure noise(NRP). We design a Sagnac effect quantum enhancement criterion(SQEC) to judge whether some quantum light can enhance Sagnac effect and present a Sagnac effect enhancement scheme that utilizing Fock state light and parity measurement technique to extract the output phase. The results of the theoretical analysis show that the maximum sensitivity can be reached at θ = 0, and the phase precision can break through SNL and even achieve Heisenberg limit(HL). When the Fock state average photon number n is far less than coherent state, the minimum measurable angular rate is improved with (2n+1)~(1/2) times, which can deduce shot noise and increase NRP little. 相似文献
3.
Optical interference fringes due to unwanted etalons are often the limiting uncertainty in diode laser spectroscopic trace gas measurements. Temporal variations in the fringe spacings, phases, and amplitudes introduce systematic baseline changes that limit useful signal averaging times to ∼1000 s, and constrain minimum detectable absorbances to between one and three orders of magnitude worse than the fundamental limiting noise sources (shot noise and/or detector thermal noise). We describe an adaptive numerical filtering method based on singular value decomposition (SVD) that shows, for the system studied, a fivefold reduction in baseline drift due to unwanted etalons over a one-week-measurement period. The adaptive algorithm is fast (<1 ms per computation), robust, and uses linear methods. It is computationally equivalent to principal component analysis (PCA). The test system was acetylene detected using a near-infrared telecommunications laser operating at 6541.96 cm-1. The gas detection limit was 20 ppb (1σ) over the one-week measurement. PACS 07.05.Kf; 07.07.Df; 07.60.-j; 42.60.-v; 42.62.-b; 42.62.Fi 相似文献
4.
Low noise, continuous-wave single-frequency 1.5-μm laser generated by a singly resonant optical parametric oscillator 下载免费PDF全文
We report a low noise continuous-wave (CW) single-frequency 1.5-μm laser source obtained by a singly resonant optical parametric oscillator (SRO) based on periodically poled lithium niobate (PPLN). The SRO was pumped by a CW single-frequency Nd:YVO4 laser at 1.06 μm. The 1.02 W of CW single-frequency signal laser at 1.5 μm was obtained at pump power of 6 W. At the output power of around 0.75 W, the power stability was better than ±1.5% and no mode-hopping was observed in 30 min and frequency stability was better than 8.5 MHz in 1 min. The signal wavelength could be tuned from 1.57 to 1.59 μm by varying the PPLN temperature. The 1.5-μm laser exhibits low noise characteristics, the intensity noise of the laser reaches the shot noise limit (SNL) at an analysis frequency of 4 MHz and the phase noise is less than 1 dB above the SNL at analysis frequencies above 10 MHz. 相似文献
5.
P. Gorrotxategi-Carbajo E. Fasci I. Ventrillard M. Carras G. Maisons D. Romanini 《Applied physics. B, Lasers and optics》2013,110(3):309-314
We report on the first application of Optical Feedback-Cavity Enhanced Absorption Spectroscopy to formaldehyde trace gas analysis at mid-infrared wavelengths. A continuous-wave room-temperature, distributed-feedback quantum cascade laser emitting around 1,769 cm?1 has been successfully coupled to an optical cavity with finesse 10,000 in an OF-CEAS spectrometer operating on the ν2 fundamental absorption band of formaldehyde. This compact setup (easily transportable) is able to monitor H2CO at ambient concentrations within few seconds, presently limited by the sample exchange rate. The minimum detectable absorption is 1.6 × 10?9 cm?1 for a single laser scan (100 ms, 100 data points), with a detectable H2CO mixing ratio of 60 pptv at 10 Hz. The corresponding detection limit at 1 Hz is 5 × 10?10 cm?1, with a normalized figure of merit of 5 × 10?11cm $^{-1}/\sqrt{\rm Hz}$ (100 data points recorded in each spectrum taken at 10 Hz rate). A preliminary Allan variance analysis shows white noise averaging down to a minimum detection limit of 5 pptv at an optimal integration time of 10 s, which is significantly better than previous results based on multi-pass or cavity-enhanced tunable QCL absorption spectroscopy. 相似文献
6.
7.
A. Foltynowicz P. Masłowski A. J. Fleisher B. J. Bjork J. Ye 《Applied physics. B, Lasers and optics》2013,110(2):163-175
We demonstrate the first cavity-enhanced optical frequency comb spectroscopy in the mid-infrared wavelength region and report the sensitive real-time trace detection of hydrogen peroxide in the presence of a large amount of water. The experimental apparatus is based on a mid-infrared optical parametric oscillator synchronously pumped by a high-power Yb:fiber laser, a high-finesse broadband cavity, and a fast-scanning Fourier transform spectrometer with autobalancing detection. The comb spectrum with a bandwidth of 200 nm centered around 3.76 μm is simultaneously coupled to the cavity and both degrees of freedom of the comb, i.e. the repetition rate and carrier envelope offset frequency, are locked to the cavity to ensure stable transmission. The autobalancing detection scheme reduces the intensity noise by a factor of 300, and a sensitivity of 5.4×10?9 cm?1?Hz?1/2 with a resolution of 800 MHz is achieved (corresponding to 6.9×10?11 cm?1?Hz?1/2 per spectral element for 6000 resolved elements). This yields a noise equivalent detection limit for hydrogen peroxide of 8 parts-per-billion (ppb); in the presence of 2.8 % of water the detection limit is 130 ppb. Spectra of acetylene, methane, and nitrous oxide at atmospheric pressure are also presented, and a line-shape model is developed to simulate the experimental data. 相似文献
8.
Ultra-sensitive mid-infrared cavity leak-out spectroscopy using a cw optical parametric oscillator 总被引:1,自引:0,他引:1
A. Popp F. Müller F. Kühnemann S. Schiller G. von Basum H. Dahnke P. Hering M. Mürtz 《Applied physics. B, Lasers and optics》2002,75(6-7):751-754
We report a portable, all-solid-state, mid-infrared spectrometer for trace-gas analysis. The light source is a continuous-wave
optical parametric oscillator based on PPLN and pumped by a Nd:YAG laser at 1064 nm. The generated single-frequency idler
output covers the wavelength region between 2.35 and 3.75 μm. With its narrow line width, this light source is suitable for
precise trace-gas analysis with very high sensitivity. Using cavity leak-out spectroscopy we achieved a minimum detectable
absorption coefficient of 1.2×10-9 /cm (integration time: 16 s), corresponding, for example, to a detection limit of 300 parts per trillion ethane. This sensitivity
and the compact design make this trace-gas analyzer a promising tool for various in situ environmental and medical applications.
Received: 19 September 2002 / Published online: 15 November 2002
RID="*"
ID="*"Corresponding author. Fax: +49-228/733-474, E-mail: frank.kuehnemann@iap.uni-bonn.de 相似文献
9.
von Basum G Halmer D Hering P Mürtz M Schiller S Müller F Popp A Kühnemann F 《Optics letters》2004,29(8):797-799
Spectroscopic detection of ethane in the 3-microm wavelength region was performed by means of a cw optical parametric oscillator and cavity leak-out. We achieved a minimum detectable absorption coefficient of 1.6 x 10(-10) cm 1/square root of Hz, corresponding to an ethane detection limit of 6 parts per trillion/square root of Hz. For 3-min integration time the detection limit was 0.5 parts per trillion. The levels are to our knowledge the best demonstrated so far. These frequency-tuning capabilities facilitated multigas analysis with simultaneous monitoring of ethane, methane, and water vapor in human breath. 相似文献
10.
Experimental demonstration of unconditional entanglement swapping for continuous variables 总被引:2,自引:0,他引:2
The unconditional entanglement swapping for continuous variables is experimentally demonstrated. Two initial entangled states are produced from two nondegenerate optical parametric amplifiers operating at de-amplification. Through implementing the direct measurement of the Bell-state between two optical beams from each amplifier the remaining two optical beams, which have never directly interacted with each other, are entangled. The quantum correlation degrees of 1.23 and 1.12 dB below the shot noise limit for the amplitude and phase quadratures resulting from the entanglement swapping are measured straightly. 相似文献
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A simple and robust absorption technique is developed which combines cavity enhanced absorption spectroscopy and wavelength modulation spectroscopy and measures the integrated output of unlocked cavities. The detection power of the technique is affected by peculiarities of the laser injection into a cavity causing excess noise which exceeds the shot noise. The noise and ways for its reduction are discussed. The new method is demonstrated by absorption measurements of excited carbon atoms in a microwave induced plasma. Preliminary detection limits equivalent to optical depths below 10-6 were obtained. PACS 42.55.Px; 42.62.Fi; 42.60.Mi 相似文献
13.
I. Courtillot J. Morville V. Motto-Ros D. Romanini 《Applied physics. B, Lasers and optics》2006,85(2-3):407-412
We report preliminary results on the first application of optical feedback cavity-enhanced absorption spectroscopy with a blue (411 nm) extended cavity diode laser (ECDL) for NO2 detection. While this technique was originally developed to operate with distributed feedback diode lasers in the near infrared, it is here extended to ECDLs and applied to the blue spectral region. With a simple and compact optical setup, we demonstrate from the baseline noise a minimum detectable NO2 concentration of 6×109 molecules/cm3 for a single laser scan (70 ms), which extrapolated under atmospheric conditions corresponds to 200 pptv. Signal averaging should allow further lowering of this limit. Observed absorption spectra display more structure than previous spectra obtained at lower resolution by Fourier-transform spectroscopy at the same wavelength. PACS 07.88.+y; 42.55.Px; 42.62.Fi 相似文献
14.
Jingsong Li Xiaoming Gao Li Fang Weijun Zhang Hyungki Cha 《Optics & Laser Technology》2007,39(6):1144-1149
A resonant photoacoustic detection system based on a low-power distributed feedback diode laser is developed. This sensor has been applied to the detection of acetylene (C2H2) using a specifically designed photoacoustic cell operating on its second longitudinal mode. The minimum detectable limit of about 10 parts-per-million volume (SNR=1) is achieved with an average laser power of 3.5 mW at atmospheric pressure, and an integration time constant of 3 ms; thus, the minimum detectable absorption coefficient normalised by power and bandwidth is 4.0×10−8 W cm−1/√Hz. The optimum operating pressure buffered with N2 is also investigated. The realisation of our system is described and experimental results are compared with different modulation techniques and other results reported in the literature. A number of issues arising from the conventional use of mechanical chopping of the beam can be effectively suppressed in wavelength modulation PA spectroscopy (WM-PAS) and second harmonic detection. 相似文献
15.
F. Y. Hou L. Yu X. J. Jia Y. H. Zheng C. D. Xie K. C. Peng 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,62(3):433-437
We report the experimental generation of the optical non-classical states with
1.34 μm wavelength which is close to one of the fiber telecommunication
windows (1.31 μm). The single-mode amplitude squeezed states with quantum
fluctuation of 2.3 ± 0.1 dB below the shot noise limit (SNL) and the entangled
states with quantum correlation of 1.1 ± 0.1 dB below the SNL are produced by an optical
parametric amplifier with a type-I phase-matched PPKTP crystal and a pair of properly
oriented type-II phase-matched KTP crystals, respectively. 相似文献
16.
Chirped laser dispersion spectroscopy (CLaDS) has been introduced recently as a technique that performs molecular detection based on measurement of optical dispersion. In this paper, a new detection scheme based on chirp modulation (CM) and subsequent phase-sensitive detection is described. CM-CLaDS inherits the full advantages of conventional CLaDS and additionally overcomes some of its limitations. A prototype CM-CLaDS instrument has been developed and characterized in laboratory conditions. The system is based on a distributed feedback quantum cascade laser which operates around 4.52???m and can probe the most intense nitrous oxide (N2O) ro-vibrational transitions. Preliminary performance tests are presented and provide a path/bandwidth normalized minimum N2O detection limit below 100?ppbv?m/Hz1/2. 相似文献
17.
A.K.Y. Ngai S.T. Persijn I.D. Lindsay A.A. Kosterev P. Gro? C.J. Lee S.M. Cristescu F.K. Tittel K.-J. Boller F.J.M. Harren 《Applied physics. B, Lasers and optics》2007,89(1):123-128
A continuous wave optical parametric oscillator, generating up to 300 mW idler output in the 3–4 μm wavelength region, and
pumped by a fiber-amplified DBR diode laser is used for trace gas detection by means of quartz-enhanced photoacoustic spectroscopy
(QEPAS). Mode-hop-free tuning of the OPO output over 5.2 cm-1 and continuous spectral coverage exceeding 16.5 cm-1 were achieved via electronic pump source tuning alone. Online monitoring of the idler wavelength, with feedback to the DBR
diode laser, provided an automated closed-loop control allowing arbitrary idler wavelength selection within the pump tuning
range and locking of the idler wavelength with a stability of 1.7×10-3 cm-1 over at least 30 min.
Using this approach, we locked the idler wavelength at an ethane absorption peak and obtained QEPAS data to verify the linear
response of the QEPAS signal at different ethane concentrations (100 ppbv-20 ppmv) and different power levels. The detection
limit for ethane was determined to be 13 ppbv (20 s averaging), corresponding to a normalized noise equivalent absorption
coefficient of 4.4×10-7 cm-1 W/Hz1/2.
PACS 42.55.Wd; 42.65.Yj; 42.62.Fi 相似文献
18.
光外差-磁旋转-浓度调制光谱技术 总被引:1,自引:0,他引:1
介绍了一种针对瞬态分子光谱测量的新技术:光外差磁旋转浓度调制光谱技术,这种光谱技术具有很高的灵敏度,综合了光外差探测技术、磁旋转光谱技术和浓度调制光谱技术的特点,利用浓度调制光谱技术针对寿命很短的瞬态分子和激发态分子的光谱进行测量,利用光外差探测技术可以消除来自光源的幅度涨落噪声,实现散粒噪声的测量极限,利用磁旋转光谱技术可以对顺磁性分子进行选择性的测量,并且进一步提高探测灵敏度。详细讨论了这种光谱技术的工作原理,并用这种技术对O2分子的b1Σg+-X3Σg-三重禁戒跃迁光谱进行测量,获得了很好的测量信噪比。并对该技术的灵敏度作了详细的分析,估计最小相对吸收度可达1.9×10-9以及O2分子三重禁戒跃迁的吸收截面为σ=2.4×10-24cm2。 相似文献
19.
A dual-beam laser absorption spectrometer with balanced detection for high sensitivity detection of oxygen via the A-band
at 760 nm is described. The 2×2 vertical-cavity surface-emitting laser arrays used for this set-up are characterized by their
wavelength tuning behavior with temperature and current, amplitude modulation, side-mode suppression ratio and polarization
contrast. The spectrometer performance is determined over time periods of up to 10 h using the variation in the differential
absorption between two beam paths. With the R11R11 line at STP, 670 μW laser power and 200 mm-long absorption cells, we realized
an excellent linearity (R=0.9999) and over a 5-min interval a record sensitivity for VCSEL-based spectrometers of 35 ppmV,
corresponding to an optical density (O.D.) of 7×10-7. For this specific set-up, this sensitivity is only a factor of 2.7 above the shot noise limit, giving us a normalized detection
limit of 7.6 ppmV·m·. Over a 10-h interval we achieved a standard deviation of 65 ppmV.
Received: 26 July 2000 / Revised version: 1 November 2000 / Published online: 6 December 2000 相似文献
20.
We report on the detection of picosecond pulsed squeezed light generated by an optical parametric amplification in a periodically poled MgO:LiNbO(3) waveguide. By using a temporally shaped local oscillator in a balanced homodyne detection, we obverved the squeezing of -5.0 dB below the shot noise level. The squeezing level at the exit of the waveguide was estimated to be -9.7±0.8 dB. 相似文献