Optical waveguides – Directional optical modulation within an optical waveguide – Light intensity dependent
Reexamination Certificate
2005-03-22
2005-03-22
Ullah, Akm Enayet (Department: 2874)
Optical waveguides
Directional optical modulation within an optical waveguide
Light intensity dependent
C385S122000, C359S326000
Reexamination Certificate
active
06870970
ABSTRACT:
The present invention provides a method for fast switching of optical properties in photonic crystals using pulsed/modulated free-carrier injection. The results disclosed herein indicate that several types of photonic crystal devices can be designed in which free carriers are used to vary dispersion curves, stop gaps in materials with photonic bandgaps to vary the bandgaps, reflection, transmission, absorption, gain, or phase. The use of pulsed free carrier injection to control the properties of photonic crystals on fast timescales forms the basis for all-optical switching using photonic crystals. Ultrafast switching of the band edge of a two-dimensional silicon photonic crystal is demonstrated near a wavelength of 1.9 μm. Changes in the refractive index are optically induced by injecting free carriers with 800 nm, 300 fs pulses. Band-edge shifts have been induced in silicon photonic crystals of up to 29 nm that occurs on the time-scale of the pump pulse. The present invention also provides a method of producing a virtual or temporary photonic crystal using free carrier injection into pure semiconductors, bulk or thin film, in which the carriers are generated in patterns which create a patterned refractive index contrast used to steer light beams in the semiconductor while it is being pulsed.
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Gosele Ulrich
Leonard Stephen W.
Schilling Jorg
Senz Stefan
van Driel Henry M.
Hill & Schumacher
Schumacher Lynn C.
Ullah Akm Enayet
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