Single mode

Single mode generation can be achieved by carefully controlling the frequency and wavenumber bandwidths of the excitation. The frequency bandwidth can readily be limited by employing windowed toneburst excitation signals [2] while the wavenumber bandwidth is... 

Of course, real molecules are not hamronic oscillators, and the energy level expression can be expanded in powers of (v + 1/2). For a single mode we have... 

Johnson A M and Shank C V 1989 Pulse compression in single-mode fibres—picoseconds to femtoseconds The Supercontinuum Laser Source ed R R Alfano (New York Springer) pp 399-449... 

Figure B2.5.17. (a) Time-dependent intensity / and redueed fluenee F/Fq for a single-mode CO2 laser pulse used in the IR laser photolysis of CF I. Fq is the total fluenee of the laser pulse, (b) VIS-REMPI iodine atom signals obtained with CO2 laser pulses of different fluenee (after [113]).

As described above for small a and NA, a fibre is single mode if U < 2.405. Here only one mode, with one group velocity, is possible. This lack of modal dispersion is why single-mode fibre dominates transport media in long-haul communication systems. 

The method shown affords easy generalization to higher order coupling in the important case where a single mode is engaged, that is, G i = g i = (l/i /2) e . Then the two off-diagonal terms derived above are, after physics-based constant coefficients have been affixed, in the upper right comer... 

Fig. 3. Types of optical fiber (a) multimode stepped index, (b) multimode graded index, and (c) single-mode stepped index.

Fig. 5. (a) Types of dispersion A, material B, total chromatic and C, waveguide, (b) Dispersion in single-mode lightguides where (—) corresponds to a 1.3... 

B. MacChesney, D. W. Johnson, P.. Lemaire, L. G. Cohen, and E. M. Rabinovich, "FluorosUicate Substrate Tubes to Eliminate Leaky-Mode Losses in MCVD Single-Mode Fibers with Depressed Index Cladding," paper no. WH2 in Technica/ Digest of Optica/ Fiber Communications Conference, San Diego, Ca/if, Optical Society of America, Washington, D.C., 1985. 

In addition, the frequency cooo, as well as the tunneUng distance can also be extracted from the same empirical data. Thus all the information needed to construct a PES is available. Of course, this PES is a rather crude approximation, since all the skeleton vibrations are replaced by a single mode with effective frequency cooo and coupling parameter C. From the experimental data it is known that the strong hydrogen bond (roo < 2.6 A) is usually typical of intramolecular hydrogen transfer. 

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