We have performed thermal diffusion measurements
of nanofluid containing gold and rhodamine 6G dye
in various ratios. At certain concentrations, gold is nearly
four times more efficient than water in dissipating small
temperature fluctuations in a medium, and therefore it will
find applications as heat transfer fluids. We have employed
dual-beam mode-matched thermal lens technique for the
present investigation. It is a sensitive technique in measuring
photothermal parameters because of the use of a lowpower,
stabilized laser source as the probe. We also present
the results of fluorescence measurements of the dye in the
nanogold environment.
Bindu M, Krishna; Manu P, John; Nandakumaran, V M(Indian Academy of Sciences, February , 2010)
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Abstract:
Chaotic synchronization of two directly modulated semiconductor lasers with
negative delayed optoelectronic feedback is investigated and this scheme is found to be
useful for e±cient bidirectional communication between the lasers. A symmetric bidirec-
tional coupling is identified as a suitable method for isochronal synchronization of such
lasers. The optimum values of coupling and feedback strength that can provide maxi-
mum quality of synchronization are identified. This method is successfully employed for
encoding/decoding both analog and digital messages. The importance of a symmetric
coupling is demonstrated by studying the variation of decoding efficiency with respect to
asymmetric coupling.
Bindu M, Krishna; Manu P, John; Nandakumaran, V M(Elsevier, April , 2010)
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Abstract:
Isochronal synchronisation between the elements of an array of three mutually coupled directly modulated semiconductor lasers is utilized for the purpose of simultaneous bidirectional secure communication. Chaotic synchronisation is achieved by adding the coupling signal to the self feedback signal provided to each element of the array. A symmetric coupling is effective in inducing synchronisation between the elements of the array. This coupling scheme provides a direct link between every pair of elements thus making the method suitable for simultaneous bidirectional communication between them. Both analog and digital messages are successfully encrypted and decrypted simultaneously by each element of the array.