scholarly journals Effect of Nonlinear Level Crossing on the Output of a Gas Laser

1975 ◽  
Vol 28 (6) ◽  
pp. 665
Author(s):  
BK Mohanty ◽  
N Nayak
Keyword(s):  
Single Mode ◽  
Level Crossing ◽  
Third Order ◽  
Intensity Parameter ◽  
Gas Laser ◽  
Two Photon ◽  
The Third ◽  
Photon Process ◽  
Limit Approximation ◽  
Lorentzian Shape

A generalized expression for electromagnetic polarization under level crossing in a single-mode gas laser is derived up to the third order in the field strength. This is made possible by the use of the probability integral of complex arguments to avoid the Doppler limit approximation. The level crossing effect is seen to appear in the third order, and its linewidth is shown to be asymmetric. It is also broader than the Lorentzian shape usually obtained under the Doppler limit. The dimensionless intensity parameter of the laser field is seen to lose its symmetry about the resonance value in the presence of level crossing. This is attributed to incoherence among different transitions. Further, the other terms like those describing the two-photon process in the third-order value are briefly discussed.

SU(1,1) SQUEEZED STATES AS DAMPED OSCILLATORS

1989 ◽  
Vol 03 (16) ◽  
pp. 1213-1220 ◽  
Author(s):  
E. CELEGHINI ◽  
M. RASETTI ◽  
M. TARLINI ◽  
G. VITIELLO
Keyword(s):  
Quantum Optics ◽  
Coherent States ◽  
Single Mode ◽  
Explicit Construction ◽  
Squeezed States ◽  
Two Photon ◽  
Generalized Coherent States ◽  
Photon Process ◽  
Damped Oscillators ◽  
Damped Oscillator

The conventional squeezed states of quantum optics, which can be thought of as generalized coherent states for the algebra SU(1,1), are dynamically generated by single-mode hamiltonians characterized by two-photon process interactions. By the explicit construction of a (highly non-linear) faithful realization of the group [Formula: see text] of automorphisms of SU(1,1), such hamiltonians are shown to be equivalent — up just to elements of [Formula: see text] — to that describing quantum mechanically a damped oscillator.

Two-Photon Absorption and Degenerate Four-Wave Mixing Studies of Sulfide Semiconductor Nanoparticles in Polymeric Solutions

2008 ◽  
Vol 8 (3) ◽  
pp. 1364-1370 ◽  
Author(s):  
Wenling Jia ◽  
Fengqi Guo ◽  
Elliot P. Douglas ◽  
Wenfang Sun
Keyword(s):  
Four Wave Mixing ◽  
Semiconductor Nanoparticles ◽  
Photon Absorption ◽  
Wave Mixing ◽  
Absorption Coefficients ◽  
Third Order ◽  
Two Photon Absorption ◽  
Two Photon ◽  
The Third ◽  
Degenerate Four Wave Mixing

The two-photon absorption coefficients (β) and the third-order nonlinear susceptibilities (χ(3)) of several semiconductor nanoparticles (CdS, CdxAg1–xS, and core–shell CdS/Ag2S) that are confined and stabilized by random and block ionomers have been measured by nonlinear transmission and degenerate four-wave mixing techniques using 21 picosecond laser pulses at near-infrared spectral region. The imaginary part of the third-order nonlinear susceptibility that is related to the two-photon absorption coefficient was then calculated. The absorptive nonlinearity of the nanoparticles (2∼9 nm) was found to be dependent on the particle size, composition and wavelength, i.e., larger CdS particles exhibit higher two-photon absorption coefficients and the presence of Ag improves two-photon absorption of CdS nanoparticles. The obtained two-photon absorption coefficients of nanoparticles corrected for their volume fraction in solution are significantly greater that those of corresponding bulk semiconductors.

TWO-PHOTON ABSORPTION IN QUANTUM DOTS OFCdSxSe1-xUSING OPEN APERTURE Z-SCAN AND FEMTOSECOND LASER

NANO ◽  
2009 ◽  
Vol 04 (01) ◽  
pp. 23-29 ◽  
Author(s):  
JITENDER KUMAR ◽  
A. VERMA ◽  
P. K. PANDEY ◽  
P. K. BHATNAGAR ◽  
P. C. MATHUR ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Femtosecond Laser ◽  
Photon Absorption ◽  
Open Aperture ◽  
Annealing Duration ◽  
Third Order ◽  
Two Photon Absorption ◽  
Two Photon ◽  
The Third ◽  
Rate Of Increase

Two-photon optical nonlinear absorption has been studied in quantum dots of CdSxSe1-xgrown in borosilicate glass matrix by two-step annealing technique. Femtosecond laser and open aperture Z-scan technique has been used for measuring the third-order nonlinear two-photon absorption coefficient (β(3)). Only the third-order and not the fifth-order nonlinear effects are observed at low intensities (1.6–3.2 GW cm-2) of laser used in the present experiment. At such low intensities, the variation of β(3)is found to be almost intensity-independent. For a given annealing duration of the quantum dots, the value of β(3)is found to be higher for sulfur-rich samples as compared to that for selenium-rich samples. This is attributed to the presence of shallow traps formed due to sulfur vacancies in the sulfur-rich samples. Further, the value of β(3)increases with the increase in the size of quantum dots and the rate of increase of β(3)with the increase of average radius is found to be higher for sulfur-rich samples.

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