In this work modulation of laser emission from polymer
nano-structured lasers was explored
through three different optical techniques.
We show all optical control of polymer distributed feedback lasers based on polyfluorenes (PFO
and F8BT) by applying a gating pulse, which completely switch-off emission in the sub-ps time
scale. The switching mechanism is assigned to photo-injection of charge carriers induced by the
gate transition. This is a resonant non-linear process, that might work at high bit-rate, paving the
way toward plastic, large-scale integrated, ultrafast optical logic.
New opportunities may also be offered by two other techniques:
Two-photon two-color pumping
allows lasing action only in presence of two different pulses, one in the visible and one in the IR,
resonant with the second telecommunication window. This may allow to convert
telecommunication signal from a fiber to visible range and thus to Plastic Optical Fibers for organic
photonics. Another technique we explored uses a blend of F8BT and a photochromic material,
(1,2-bis-(5-phenyl-2-methyl-3-tienyl) perfluocyclopentene))(C4). With a UV pulse we are able to
change C4 structure, thus overlapping its absorption spectrum with F8BT emission and modulating
yellow ASE emission.
KEYWORDS: Sensors, Cones, Retina, Color vision, Multispectral imaging, Visual system, Human vision and color perception, Resolution enhancement technologies, Machine vision, Human subjects
In principle, an artificial retina should mimic as much as possible the spectral sensitivities of the real retina.
For technological reasons, building such an artificial device can lead to spectral approximations in comparison
with the real sensitivities. To understand if possible discrepancies can determine big differences in the final
perception, the whole visual system should be taken into consideration, not only the retinal input signal difference.
This paper aims at investigate how retinal sensitivity differences should affect the final perception. However,
answering to this question is a very complex problem related to the whole visual system, that we do not want
to extensively address in this paper. We only want to investigate the relationship between the spatial aspects
of color perception and the spectral differences among cone sensitivities. Moreover, a personal interdifference
has been observed in cone spatial distribution between human subjects, without any corresponding significant
difference in final color sensation. It is likely that spatial compensation, performed by human observers, strongly
decreases this subjectivity in color signal. We aim at address if a similar principle should be considered in
artificial vision. In this paper we analyze the interdifference among integrated values obtained using different
organic-based artificial sensors with different spectral sensitivities. Experiments show a significant decrease of
the effect of spectral sensitivity sensor differences when a spatial color correction is applied.
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