High Resolution Etching of Gaas and Cds Crystals

1982 ◽  
Vol 17 ◽  
Author(s):  
D. V. Podlesnik ◽  
H.H. Gilgen ◽  
R.M. Osgood ◽  
A. Sanchez ◽  
V. Daneu
Keyword(s):  
High Resolution ◽  
Surface Properties ◽  
Laser Intensity ◽  
Optical Measurements ◽  
Laser Beams ◽  
Etching Time ◽  
Grating Fabrication ◽  
High Laser ◽  
High Laser Intensity

ABSTRACTSubmicrometer gratings have been etched in GaAs and CdS crystals which have been immersed in an oxidizing etch and illuminated with interferring laser beams. A resolution of 170 nm was obtained. At high laser intensity and with prolonged etching time the surface properties of the material are degraded. The use of in-situ optical measurements of grating parameters allows ready optimization of the grating fabrication process.

Quantitative fs-TALIF in high-pressure NRP discharges: Calibration using VUV absorption spectroscopy

2021 ◽  
Author(s):  
Ciprian Dumitrache ◽  
Arnaud Gallant ◽  
Nelson de Oliveira ◽  
Christophe O Laux ◽  
Gabi Daniel Stancu
Keyword(s):  
Laser Intensity ◽  
Limit Of Detection ◽  
Diagnostic Technique ◽  
Low Pressure ◽  
Photon Absorption ◽  
Post Discharge ◽  
Pure Nitrogen ◽  
High Laser ◽  
High Laser Intensity ◽  
Intensity Regime

Abstract This work presents a femtosecond two-photon absorption laser-induced fluorescence (fs-TALIF) diagnostic for measuring ground-state atomic nitrogen in nanosecond repetitively pulsed (NRP) discharges. Absolute atom density is obtained from the TALIF signal via a novel calibration technique based on one-photon direct absorption measurements performed in a low-pressure DC discharge. The VUV measurements were done at the Soleil synchrotron facility using the high-resolution Fourier-transform spectrometer (minimum linewidth Δ̃ = 0.08 cm-1). The main goal of this work was to develop a quench-free diagnostic technique, which would allow measurements at elevated pressures with high spatial and temporal resolution. Here fs-TALIF measurements of N(4S) are demonstrated in the NRP post-discharge between 1-500 μs after the nanosecond high-voltage pulse. A maximum number density of N-atoms of × − was measured at 1 μs after the pulse when the discharge was operated at 1 bar in pure nitrogen. This corresponds to a dissociation fraction of ~ 0.1 %. The fs-TALIF technique at high laser intensity regime (> 1 TW cm-2) calibrated using VUV absorption was compared with the fs-TALIF at low laser intensity regime (< 100 MW cm-2) calibrated via the well-established non-saturated TALIF technique using krypton as an etalon gas. It was found that the two measurements of N(4S) in the NRP post-discharge agree within a factor of 3. Importantly, the limit of detection of the fs-TALIF at high laser intensity regime was determined to be ()~ e 1/. This is approximately one order of magnitude better than previously reported by ns-TALIF in low-pressure discharges.

The Influence of High-Frequency Phase of Laser Wavefront on the Distribution of Focal Spot

2014 ◽  
Vol 644-650 ◽  
pp. 1433-1437
Author(s):  
Fu Xing Fu
Keyword(s):  
Laser Beam ◽  
Surface Properties ◽  
High Frequency ◽  
Focal Spot ◽  
Laser Intensity ◽  
Side Lobe ◽  
Laser Beams ◽  
Damage Effect ◽  
Frequency Phase ◽  
Peak Value

When laser beam is effected on the material, the surface properties of material can be damaged, and the damage effect is different for the different laser beams. Nevertheless, the distribution of laser intensity is influenced by the proportion of high-frequency phase in wavefront. By researching the propagation character of wavefront phase, the relation of high-frequency phase and laser intensity is given in this paper. The results show that the focal spot increases gradually with the increase of the proportion of high-frequency phase, the peak value of intensity decreases obviously, and the number of side lobe increases observably.

Multiphoton Ionization of Rare Gases at Very High Laser Intensity (1015W/cm2) by a 30-psec Laser Pulse at 1.06 μm

1976 ◽  
Vol 36 (16) ◽  
pp. 949-952 ◽  
Author(s):  
L. A. Lompre ◽  
G. Mainfray ◽  
C. Manus ◽  
S. Repoux ◽  
J. Thebault
Keyword(s):  
Laser Pulse ◽  
Laser Intensity ◽  
Multiphoton Ionization ◽  
Rare Gases ◽  
High Laser ◽  
Very High ◽  
High Laser Intensity

Multiple Harmonic Generation in Rare Gases at High Laser Intensity

The Electron ◽  
1991 ◽  
pp. 321-332
Author(s):  
Anne L’huillier ◽  
Louis-André Lompre ◽  
Mainfray Gérard
Keyword(s):  
Harmonic Generation ◽  
Laser Intensity ◽  
Rare Gases ◽  
High Laser ◽  
High Laser Intensity

Coherent Transients in a Gas 13CH3F Generated by Step Switch of Electric Field

2011 ◽  
Vol 6 (3) ◽  
pp. 5-10
Author(s):  
Anton A. Rozhin ◽  
Dmitry V. Ledovskikh ◽  
Natalia N. Rubtsova
Keyword(s):  
Electric Field ◽  
Vibration Mode ◽  
Laser Intensity ◽  
Rotational Transition ◽  
Low Intensity ◽  
High Laser ◽  
Decay Signal ◽  
Resonant Radiation ◽  
High Laser Intensity ◽  
Free Polarization

Transient signals of optical nutations and free polarization decay arising in a gas 13CH3F (rotational transition R(4,3) of vibration mode 0–1 ν3 ) at the step-wise switch of electric field in the presence of resonant radiation of CO2 laser are investigated. In the limit of low intensity of radiation the peaks of free polarization decay are observed; the frequency of their appearance is proportional to the electric field strength. The number of observable peaks of free polarization decay decreases at laser intensity growth, and free polarization decay signal becomes indistinguishable at a background of optical nutations at high laser intensity. At high laser intensity the signal of transient optical nutations dominates. Results of calculations are in qualitative agreement with experimental data

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