Radhakrishnan, P; V P N Nampoori; Girijavallabhan, C P; Shelly John, M(Measurement Science and Technology, UK, November 12, 1998)
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Abstract:
A novel sensing technique for the in situ monitoring of the rate of pulsed laser
deposition (PLD) of metal thin films has been developed. This optical fibre based sensor
works on the principle of the evanescent wave penetration of waveguide modes into the
uncladded portion of a multimode fibre. The utility of this optical fibre sensor is
demonstrated in the case of PLD of silver thin films obtained by a Q-switched Nd:YAG laser
which is used to irradiate a silver target at the required conditions for the preparation of thin
films. This paper describes the performance and characteristics of the sensor and shows how
the device can be used as an effective tool for the monitoring of the deposition rate of silver
thin films. The fibre optic sensor is very simple, inexpensive and highly sensitive compared
with existing techniques for thin film deposition rate measurements
Radhakrishnan, P; Girijavallabhan, C P; Nibu, A George; Aneeshkumar, B(Journal of Physics D : Applied Physics, April 7, 1999)
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Abstract:
The photobleaching of the lasing dye Rhodamine 6G embedded in the solid
matrix poly(methyl methacrylate) was investigated using a photoacoustic technique.
Chopped laser radiation from an argon ion laser at four different wavelengths was used for
the study. Experimental results indicate that the photobleaching rate is directly proportional
to the incident laser power while it decreases with increase in concentration of the dye
molecules. In the present case we have not observed any dependence of photobleaching on
the chopping frequency. One-photon absorption is found to be responsible for the
photobleaching of the dye within the selected range of laser power.