| Budget Amount *help |
¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2005: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2004: ¥2,100,000 (Direct Cost: ¥2,100,000)
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| Research Abstract |
We studied nonlinear dynamics of laser-diode (LD)-pumped microchip solid-state lasers for finding generic behaviors inherent in complex systems toward a new field nonlinear laser science. A promising application of LD-pumped microchip lasers to self-mixing laser-Doppler measurements has also been investigated.
1.NONLINEAR DYNAMICS
i)Using LD-pumped microchip multimode lasers, we have discovered such generic dynamics in complex systems as "formation of information network" and "chaos synchronization" among modes, "chaotic itinerancy" as well as "burst synchronization" experimentally. These complex dynamics have been characterized by useful methodologies we developed, such as ‘information circulation analysis' and ‘joint time-frequency analysis', and reproduced by numerical simulation of model equations.
ii)We have investigated novel transverse lasing pattern formations in LD-pumped wide-aperture thin-slice solid-state lasers with coated end-mirrors, using several materials, e.g. LNP, Nd :
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GdVO_4 and Nd:YAG ceramics. We found that formation of self-induced multiple "lasing channels" and the resultant instabilities take place in such thin laser with extremely large Fresnel numbers, resulting from small statistical roughness of reflective end surfaces polished by the standard technique as well as from grain boundaries. We discovered several new types of nonlinear transverse lasing patterns consisting of coupled "local modes" which are formed through channeling.
2.LASER MEASUREMENTS WITH EXTREME OPTICAL SENSITIVITY
i)Using LD-pumped thin-slice solid-state lasers, we have developed two-channel real-time nanometer-vibration measurement systems by introducing a ‘carrier-frequency-multiplexing' technique into self-mixing laser vibrometry we invented.
ii)We have applied our self-mixing laser vibrometry system to real-time measurements of small particles in Brownian motion. Quick and accurate measurements of sizes of Brownian particles in water, ranging from 20 nm- 10 μm, with concentrations down to 0.001% (i.e., 10 ppm) have been demonstrated successfully. We have realized real-time measurements of averaged motion of many Brownian particles and discovered random sequences of Loretz-type in averaged motion.
iii)We have succeeded in particle sizing of plankton in seawater, and velocity distributions of plankton in Brownian motion and self-mobile plankton have been have been identified with the self-mixing laser, for the first time. Less
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