Guosheng Zhou

Low-frequency wavelength modulation spectroscopy with D 2 transition of atomic cesium by use of an external-cavity diode laser

Low-frequency wavelength modulation spectroscopy is acquired with an external-cavity diode laser. The wavelength modulation is achieved with voltage tuning by means of scanning with the piezoelectric stepper motor, which rotates the end mirror in the laser cavity. With optimum 1-kHz frequency modulation and harmonic detection, direct absorption experiments for the 6S(1/2)(F = 4) --> 6P(3/2) transition of the cesium D(2) line were carried out. We found that 6f-harmonic detection is best here with a signal-to-noise voltage ratio of 460.

N-soliton solutions in the higher-order nonlinear Schroedinger equation

We investigated the possible solutions of the higher order nonlinear Schrodinger (HNLS) equation describing femtosecond optical pulses in an optical fiber system. By using the Hirota direct method, we derived a fundamental solitary wave solution for arbitrary parameters and a N-soliton solution under some conditions. The significance of the soliton solution was discussed.

Two-photon resonant three-photon ionization and atomic energy-pooling-induced ionization in potassium vapor

The decay curves of potassium ion produced by Two-Photon Resonant Three-photon Ionization were measured. From the relation between ion current and multi-photon dynamic parameter, photo-ionization cross-section of 6S state of atomic potassium was determined. Potassium atom was ionized by Energy Pooling Effect when excited wavelength was 766.4 nm or 769.8 nm corresponding to the first excited state of potassium atom.

Applications of 4f and 6f harmonics detection in resolution of modulation-broadened spectra

In this paper, the experiments are carried out by voltage modulating an external-cavity tunable diode laser (TDL). The 2f, 4f and 6f signals of the modulation frequency are measured with cesium D2 line and the experiment results are compared with theory. Studying results in that there are certain advantages to be gained by going to harmonic- detection greater than usual second (2f) the smaller signal strength at higher harmonics notwithstanding. It is shown that nearly overlapping lines may be better resolved by using 4f and 6f harmonic detection considering the much less modulation-broadened spectra. Results are applicable to trace gas detection using TDLs, and to other areas of spectroscopy and magnetic resonance where harmonic detection techniques are routinely employed to monitor weak signals.

Low-frequency wavelength modulation spectroscopy using an external-cavity diode laser

A low-frequency wavelength modulation spectroscopy is acquired with a Harvey-Myatt external-cavity diode laser. The wavelength modulation is achieved using the voltage tuning by scanning the piezoelectric stepper motor with rotating of the end mirror in the laser cavity. With optimum modulation frequency 1-kHz and harmonic detection direct absorption experiments with cesium D2 line were carried out. We find that 6f-harmonic detection is best here with the signal-to-noise voltage ratio being 460.

Quasi-soliton in optical fiber link with periodical dispersion management and power balance

Quasi-soliton exits in optical fibre link with periodical dispersion management and power balance. The analytical approximate expressions for the quasi-soliton are given. The evolution of the optical pulse width has the shape like a saw-tooth. The pulse width at the end of each unit cell is basically dependent on balance the average dispersion and nonlinear effect

Liquid thermal diffusivity measurement by pulsed photothermal deflection technique

In this paper the liquid thermal diffusivity measurement through pulsed photothermal deflection in a modified collinear configuration is presented and discussed. The condition that the pulsed beam is regarded as in the form of a Dirac delta function here is given out. Comparison between theory and experiment is also shown.

Optical pulse with time-space asymmetry in saturable self-focusing Kerr medium

The problem of propagation of (2 + 1) dimensional optical pulse with time-space asymmetry in a saturable Kerr medium is discussed. That pseudo-momentum and energy of the optical pulse keep conservative along propagation is obtained by using variational method. The impacts of initial asymmetry, saturable strength and coupling strength on pulse width, beam width are studied by using numerical method.

Interplay among diffraction, dispersion, and nonlinearity in two spatial dimensions

The combined effect of diffraction, anomalous dispersion and nonlinear refraction under both symmetric and unsymmetric initial conditions is studied by using a variational approach and numerical simulation. It is shown that the compression parameter Bo which strongly depends on the initial condition and the nonlinear interplay strength, plays an important role. When Bo > 0, the beam width and pulse width blow up vibrantly as z yields (infinity) . When Bo < 0, the pulse collapses oscillatorily and simultaneously both in space and time.