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Dual-wavelength laser source for onboard atom interferometry

Tue, 2011-11-01 02:00 — Guest

V. Ménoret, R. Geiger, G. Stern, N. Zahzam, B. Battelier, A. Bresson, A. Landragin, P. Bouyer
We present a compact and stable dual-wavelength laser source for onboard atom interferometry with two different atomic species. It is based on frequency-doubled telecom lasers locked on a femtosecond optical frequency comb. We take advantage of the maturity of fiber telecom technology to reduce the ... [Opt. Lett. 36, 4128-4130 (2011)]

Continuous-wave subwavelength microdisk lasers at λ = 1.53 µm

Mon, 2010-08-30 02:00 — Guest

Zhijun Liu, Jeffrey M. Shainline, Gustavo E. Fernandes, Jimmy Xu, Jianxin Chen, Claire F. Gmachl
Subwavelength InGaAs/AlInAs microdisk lasers are demonstrated under continuous-wave optical pumping at a heat-sink temperature of 45 K. A 1.49 µm diameter, 209 nm thick microdisk lases in single-mode at a wavelength of 1.53 µm, which is identified as the whispering-gallery mode with the ... [Opt. Express 18, 19242-19248 (2010)]

Isotopic composition and concentration measurements of atmospheric CO2 with a diode laser making use of correlations between non-equivalent absorption cells

Sat, 2010-08-21 07:44 — Guest

Abstract  
Correlations between a sample and a sealed reference cell of a tunable diode laser spectrometer for the measurement of the
isotopic composition (δ
13C) and the concentration of atmospheric carbon dioxide in air have been investigated. Likely due to fluctuations of the laser
emission profile, these correlations have been used to improve the performance of the instrument. In a comparison with isotope
ratio mass spectrometer and gas chromatographic measurements, an accuracy of 0.15‰ for δ
13C and 0.05 ppmv for the CO2 concentration is demonstrated for 40 s integration time. Long-term stability and field deployment of the instrument have
been investigated during a few days measurement campaign in Paris.

Evaluation of bimaterial cantilever beam for heat sensing at atmospheric pressure

Fri, 2010-05-14 00:00 — Guest

Masaya Toda, Takahito Ono, Fei Liu, and Ioana Voiculescu
The bimaterial cantilever beam is an important basic structure of microelectromechanical system thermal devices. The research described in this paper is a study of the deflection of the bimaterial cantilever beam operated in the air and irradiated with a laser beam at the free end. The bimaterial ca ... [Rev. Sci. Instrum. 81, 055104 (2010)] published Thu May 13, 2010.

Optically induced fast wavelength modulation in a quantum cascade laser

Thu, 2010-07-08 00:02 — Guest

Gang Chen, Rainer Martini, Seong-wook Park, Clyde G. Bethea, I.-Chun A. Chen et al.
An optically induced fast wavelength shift is demonstrated in a standard middle infrared (MIR) quantum cascade laser (QCL) by illuminating the front facet with a femtosecond (fs) near infrared (NIR) laser, allowing fast optical frequency modulation (FM) for free space optical communication (FSOC) an ... [Appl. Phys. Lett. 97, 011102 (2010)] published Wed Jul 7, 2010.

Angular effects of nanostructure-covered femtosecond laser induced periodic surface structures on metals

Tue, 2010-10-12 00:00 — Guest

Taek Yong Hwang and Chunlei Guo
In this paper, we study nanostructure-covered laser induced periodic surface structures (NC-LIPSSs) on metals produced by femtosecond laser pulses incident at various angles. For the first time, we show that the dependence of NC-LIPSS period on the incident beam angle deviates significantly from tha ... [J. Appl. Phys. 108, 073523 (2010)] published Mon Oct 11, 2010.

VECSEL Optimization Using Microscopic Many-Body Physics

Tue, 2011-12-06 23:00 — Guest

Vertical external cavity surface-emitting lasers (VECSELs) are designed and analyzed using an approach based on fully microscopically computed material properties like gain and carrier recombination rates. Very good agreement between theoretical predictions and measured characteristics of the realized devices is demonstrated. The high accuracy of the theoretical models allows one to determine even small deviations between the nominal designs and actual realizations. The models are used to find optimization strategies. It is shown how the external efficiency can be strongly improved using surface coatings that reduce the pump reflection while retaining the gain-enhancing cavity effects at the lasing wavelength. It is shown how incomplete pump absorption can be detrimental to the device performance and how this problem can be reduced using optimized distributed Bragg reflectors and metallization layers. A combination of improved metallization and use of such a coating more than doubles the external efficiency and maximum power for a realized VECSEL operating at 1010 nm and the theory indicates that further significant improvements are possible.

Manganite heterojunction photodetectors for femtosecond pulse laser measurements

Sat, 2012-02-25 23:59 — Guest

Publication year: 2012
Source: Optics & Laser Technology, Available online 24 February 2012
Saisai Zhao, Kun Zhao, Hao Ni, Wenfeng Xiang, Songqing Zhao, ...
We report a sensitive photodetector, based on a manganite junction La2/3Ca1/3MnO3/Si, for femtosecond (fs) pulse laser energy per pulse and average power measurements. The La2/3Ca1/3MnO3/Si photodetector exhibitsD(normalized detectivity) greater than 5.229×10 cm Hz W. The open-circuit photovoltage and short-circuit photocurrent responsivities reach ∼268 V/mJ and ∼275 A/mJ for single pulse irradiation, respectively, and the open-circuit photovoltage responsivity reaches ∼1.7 V/W for average power illumination. The experimental results make the manganite junction a promising fs laser measurement detector and reference standard for calibrating fs lasers.

Wide temperature range 0 < T < 85 °C narrow linewidth discrete mode laser diodes for coherent communications applications

Mon, 2011-12-12 02:00 — Guest

John O’Carroll, Richard Phelan, Brian Kelly, Diarmuid Byrne, Liam P. Barry, James O’Gorman
Cost effective lasers meeting the linewidth requirements for coherent communication systems are a key element in reducing the overall cost of future coherent systems. We report on monolithic devices with linewidths as low as 138 kHz which operate in a narrow linewidth, single wavelength mode with ... [Opt. Express 19, B90-B95 (2011)]

Second harmonic generation in quantum cascade lasers pumped by femtosecond mid-infrared pulses

Tue, 2011-09-20 18:01 — Guest

Sheng Liu

(刘晟)

, Hong Cai

(蔡虹)

, Elaine Lalanne, Peter Q. Liu, Xiaojun Wang et al.
Second harmonic generation (SHG) pulses at lambda ~ 2.25 [mu]m have been obtained from a 4.5 [mu]m quantum cascade laser (QCL) when it is resonantly pumped by transverse magnetic polarized 120 fs, lambda = 4.5 [mu]m pulses through the QCL's front facet at room temperature. The measured SHG spectrum ... [Appl. Phys. Lett. 99, 122104 (2011)] published Tue Sep 20, 2011.

Spatiotemporal propagation characteristics based on the exact solutions of the generalized nonlinear Schrödinger equation by intensity moments

Fri, 2012-03-02 02:02 — Guest

Publication year: 2012
Source: Optics Communications, Available online 28 February 2012
Yangbao Deng, Xiquan Fu, Chao Tan

High power 2 MHz passively Q-switched nanosecond Nd:YVO_4/Cr^4+:YAG 914 nm laser

Thu, 2012-05-10 02:00 — Guest

Xin Yu, Renpeng Yan, Xudong Li, Yufei Ma, Deying Chen, Junhua Yu
We report a high-power, high-repetition-rate end-pumped passively Q-switched Nd:YVO_4/Cr^4+: yttrium aluminum garnet 914 nm laser. The maximum output power of 3.8 W at 914 nm is achieved at 2 MHz with the absorbed pump power of 25.2 W. The highest single pulse energy of a pulsed 914 nm laser ... [Appl. Opt. 51, 2728-2732 (2012)]

Atomic phase shifts in mixed-glass, multi-petawatt laser systems

Mon, 2011-10-10 02:00 — Guest

Catalin V. Filip
The influence of the active gain medium on the spectral amplitude and phase of amplified, femtosecond pulses in a laser system is studied. Results from a case study of a 15-petawatt laser based on Nd-doped mixed glasses show that gain-induced atomic phase shifts will distort the pulses, reducing ... [Opt. Express 19, 20953-20959 (2011)]

Chaotic dynamics of erbium-doped fiber laser with nonlinear optical loop mirror

Thu, 2011-09-29 02:52 — Guest

Publication year: 2011
Source: Optics Communications, Available online 28 September 2011
Lingzhen Yang, Li Zhang, Rong Yang, Li Yang, Baohua Yue, ...
We experimentally and numerically demonstrate the chaotic dynamics of the erbium-doped fiber laser with a nonlinear optical loop mirror. When the polarization controllers are fixed at an appropriate orientation, we observe that the fiber laser exhibits a period-doubling route to chaos with increasing the pump power in the experiment and simulation. The numerical simulation shows a good agreement with the experimental results. The results show experimentally and numerically that the chaotic dynamics of the erbium-doped fiber laser is related to the polarization state and the pump power of light in the cavity.

Mathematic model analysis of Gaussian beam propagation through an arbitrary thickness random phase screen

Mon, 2011-09-12 02:00 — Guest

Yuzhen Tian, Jin Guo, Rui Wang, Tingfeng Wang
In order to research the statistical properties of Gaussian beam propagation through an arbitrary thickness random phase screen for adaptive optics and laser communication application in the laboratory, we establish mathematic models of statistical quantities, which are based on the Rytov method ... [Opt. Express 19, 18216-18228 (2011)]

Spectral Analysis of Quantum-Dash Lasers: Effect of Inhomogeneous Broadening of the Active-Gain Region

Tue, 2012-03-06 01:00 — Guest

The effect of the active region inhomogeneity on the spectral characteristics of InAs/InP quantum-dash (Qdash) lasers is examined theoretically by solving the coupled set of carrier-photon rate equations. The inhomogeneity due to dash size or composition fluctuation is included in the model by considering dispersive energy states and characterized by a Gaussian envelope. In addition, the technique incorporates multilongitudinal photon modes and homogeneous broadening of the optical gain. The results predict a red shift in the central lasing wavelength of Qdash lasers on increasing the inhomogeneous broadening either explicitly or implicitly, which supports various experimental observations. The threshold current density and the lasing bandwidth are also found to increase.

Nanocrystalline SnO2–TiO2thin film deposited on base of equilateral prism as an opto-electronic humidity sensor

Wed, 2012-02-29 02:50 — Guest

Publication year: 2012
Source: Optics & Laser Technology, Available online 28 February 2012
B.C. Yadav, Nidhi Verma, Satyendra Singh

Stimulated Raman rotational photoacoustic spectroscopy using a quartz tuning fork and femtosecond excitation

Sat, 2011-09-10 17:47 — Guest

Abstract  
Molecular alignment of linear molecules (O2, N2, CO2 and CO) is measured photoacoustically in the gas phase. The rotational excitation is accomplished using a simple femtosecond
stimulated Raman excitation scheme, employing two femtosecond pulses with variable delay between the pulses. Molecular alignment
is determined directly by measuring the energy dumped into the gas by quartz-enhanced photoacoustic spectroscopy (QEPAS),
utilizing a quartz tuning fork as a sensitive photoacoustic transducer. The experimental results demonstrate for the first
time the use of a tuning fork for resonant photoacoustic detection of Raman spectra excited by femtosecond double pulses and
match both simulation and literature values.

Gaussian laser beam tailoring using acoustooptic cell

Sun, 2011-12-04 23:50 — Guest

Publication year: 2011
Source: Optics & Laser Technology, Available online 3 December 2011
Abdelhalim Bencheikh, Kouider Ferria
Profile shaping of a Gaussian laser beam by an acoustic wave is well described using Collins integral and ABCD matrix formalism. It is shown by a numerical simulation that the relative width of the laser beam to the ultrasonic wavelength and the acoustic pressure inside the acoustooptic cell act on the light intensity diffraction pattern.Obtained results show that the output intensity profile differs from the incident Gaussian beam shape, and it is more broadened with an increase in the acoustic pressure. The intensity of a focused laser beam is transformed in a flat form in the central region if the acoustic pressure is proprely controlled.On the other hand the intensity longitudinal range (ILR) of the flat shape is discussed along the propagation axes, we have found the ILR is about 2 mm for a focal length distancef=100 mm.

Probability density of irradiance fluctuations observed over terrestrial ranges

Sat, 2011-12-10 02:00 — Guest

Rita Mahon, Christopher I. Moore, Harris R. Burris, Mike Ferraro, William S. Rabinovich, Michel Suite, Linda M. Thomas
The irradiance fluctuations imposed on a laser beam that has propagated over horizontal terrestrial paths in the range of 2?to 24?km are compared to lognormal (LN) and gamma-gamma (GG) distributions. For the direct links reported here the irradiance fluctuations follow a LN distribution except in ... [Appl. Opt. 50, 6476-6483 (2011)]

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