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Absorption spectra of two-level atoms interacting with a strong polychromatic pump field and an arbitrarily intense probe field
No full text©1999 The American Physical Society
URL: http://link.aps.org/abstract/PRA/v60/p2547
DOI: 10.1103/PhysRevA.60.2547
PACS: 42.50.Gy, 32.80.-t, 42.50.HzA numerical method is introduced that solves the optical Bloch equations describing a two-level atom interacting with a strong polychromatic pump field with an equidistant spectrum and an arbitrarily intense monochromatic probe field. The method involves a transformation of the optical Bloch equations into a system of equations with time-independent coefficients at steady state via double harmonic expansion of the density-matrix elements, which is then solved by the method of matrix inversion. The solutions so obtained lead immediately to the determination of the polarization of the atomic medium and of the absorption and dispersion spectra. The method is applied to the case when the pump field is bichromatic and trichromatic, and the physical interpretation of the numerically computed spectra is given. [S1050-2947(99)10409-8].This research was supported in part by the Ministry of Science and Technology of Korea under Contract No. KRISS-98-0401-001 and by the Korea Atomic Energy Research Institute. One of the authors (T. H. Yoon) thanks Dr. S. A. Pulkin and J. R. Park for stimulating discussions
Chaotic Sequence and a Simple Model of Return Map in a Driven Nonlinear Oscillator Using a Light-Emitting Didoe
No full textSimple methods for measuring the linewidth enhancement factor in external cavity laser diodes
No full textWe introduce two simple methods, a current scanning method and a reflectivity scanning method, for measuring the linewidth enhancement factor(Lu) in an external cavity laser diode (ECLD). Both methods utilize the functional relationship associated with a between the emission wavelength and effective reflectivity of the compound cavity of ECLD. The change of emission wavelength as a function of an injection current and of an external reflectivity is used to determine the value of a in the current scanning method and in the reflectivity scanning method, respectively. The measured values of a: by the two methods showed a fairly good agreement. (C) 2000 Elsevier Science B.V. All rights reserved
Diffractometric methods for absolute measurement of diffraction-grating spacings
No full textWe propose one- and two-wavelength methods of absolute measurement of diffraction-grating spacings based on the Littman configuration for autocollimation. The one-wavelength method has been applied to measure on the Littman configuration for autocollimation. The one-wavelength method has been applied to measure the spacing of a grating with a nominal value of 2160 grooves/mm. The grating spacing was measured to be 463.16 nm, with an experimental standard deviation of 0.24 nm. It has been demonstrated that the both methods can provide direct traceability in the submicrometer region in terms of wavelength standards for applications in the field of nanometrology. (C) 1999 Optical Society of America
PERTURBATION ANALYSIS OF BISTABILITY AND PERIOD DOUBLING BIFURCATIONS IN DIRECTLY-MODULATED LASER-DIODES
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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