Registers – Records
Reexamination Certificate
1999-11-16
2002-06-11
Frech, Karl D. (Department: 2876)
Registers
Records
C235S454000
Reexamination Certificate
active
06402037
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to styryl dyes and compositions and to methods for using these dyes and compositions; to porous glass-polymer composites and to methods for using these composites; to methods and compositions for generating singlet oxygen and for killing cells and viruses; and to methods and media for storing and reading data generally and, more particularly, for reading and storing data in three dimensions.
BACKGROUND OF THE INVENTION
Frequency Upconversion
Frequency upconversion lasing is an important area of research and has become more interesting and promising in recent years. Compared to other coherent frequency upconversion techniques, such as optical harmonic generation or sum frequency mixing based on second- or third-order nonlinear optical processes, the major advantages of upconversion lasing techniques are: i) elimination of phase-matching requirements, ii) feasibility of using semiconductor lasers as pump sources, and iii) capability of adopting waveguide and fiber configurations. To date, two major technical approaches have been used to achieve frequency upconversion lasing: one is based on direct two-photon (or multi-photon) excitation of a gain medium (two-photon pumped); the other is based on sequential stepwise multi-photon excitation (stepwise multi-photon pumped).
The earliest reported two-photon pumped (“TPP”) lasing was observed in PbTe crystal at 15° K. by Patel et al.
Phys. Rev. Lett
. 16:971-974 (1966). The pump wavelength was 10.6 &mgr;m, and the lasing wavelength was about 6.5 &mgr;m. Since then, TPP lasing action has also been observed in a number of other semiconductor crystals (Yoshida et al.,
Japan. S. Appl. Phys
. 14:1987-1993 (1975); Gribkovskii et al.,
Sov. J. Quantum Electron
. 9:1305-1307 (1979); Gao et al.,
Proc. SPIE
-
Int. Soc. Opt. Eng
. 322:37-43 (1982); and Yang et al.,
Appl. Phys. Lett
. 62:1071-1073 (1993)), but low operating temperature (about 10 to 260° K.) requirements limited their usefulness. A few reference papers report room temperature TPP lasing in metal vapor or gas systems (Bloom et al.,
Appl. Phys. Lett
. 24:427-428 (1974); Willenberg et al.,
Appl. Phys. Lett
. 37:133-135 (1980); and Goldston et al.,
Laser Focus World
, 27:27-29 (1991)). In addition, room-temperature upconversion lasing has been successfully achieved in rare-earth-ion doped crystals (Silversmith et al.,
Appl. Phys. Lett
. 51:1977-1979 (1987); MacFarlane et al.,
Appl. Phys. Lett
. 52:1300-1302 (1988); Pollack et al.,
Appl. Phys. Lett
. 54:869-871 (1989); Nguyen et al.,
Appl. Opt
. 28:3553-3555 (1989); and McFarlane
Appl. Phys. Lett
. 54:2301-2302 (1989)), inorganic glasses (Bennett et al,.
Ceram. Trans
. 28:321-321 (1992) and Mita et al.,
Appl. Phys. Lett
. 62:802-804 (1993)), and optical fibers (Hanna et al.,
Opt. Commun
. 78:187-194 (1990) and Niccacio et al.,
IEEE J. Quantum Electron
. QE-30:2634-2638 (1994)). These systems essentially involve sequential multiple photon absorption with single photon absorption to intermediate metastable states.
By contrast, there were more reported experimental results of TPP lasing behavior in organic dye solutions using commercial dyes, such as Rhodamine 6G, Rhodamine B, dimethyl POPOP (“DMP”), and 1,3,1′,3′-tetramethyl-2,2′-dioxopyrimide-6,6′-carbocyanine hydrogen sulfate (“PYC”). (Rapp et al.,
Phys. Lett
. 8:529-531 (1971); Topp et al.,
Phys. Rev
. A3:358-364 (1971); Rubinov et al.,
Appl. Phys. Lett
. 27:358-360 (1975); Prokhorenko et al.,
Sov. S. Quantum Electron
. 11:139-141(1981); Qiu et al.,
Appl. Phys
. B48:115-124 (1989); Zaporozhchenko et al.,
Sov. J. Quantum Electron
. 19:1179-1181 (1989); and Swok et al.,
Op. Lett
. 17:1435-1437 (1992)). However, commercial applications, especially those in recording, printing, display, communication, and the like, require, compact, lightweight, inexpensive, minimal maintenance lasers. In this respect, liquid dye lasers suffer a number of drawbacks, including the toxicity of the solvents used to dissolve the dye, concern over solvent evaporation, flow fluctations in the dye solution, and difficulty of use in terms of size and maintenance. Moreover, most two-photon absorption (“TPA”) induced stimulated emissions in dye solutions are cavityless lasing or superradiation (directional ASE). Recently, TPP upconversion stimulated emission was reported by Mukherjee,
Appl. Phys. Lett
. 62, 3423-3425 (1993) in a 4-dicyanomethylene-2-methyl-6-p-dimethylaminostyryl-4H-pyran (“DCM”) doped poly(methyl methacrylate) (“PMMA”) channel waveguide configuration.
However, DCM, like most commercial and other known dyes, has a TPA cross-section of from approximately 1×10
−50
cm
4
-sec to approximately 1×10
−48
cm
4
-sec, which is insufficient to achieve practical conversion efficiencies. In addition, solid state dye lasers have low damage resistance, which has been attributed to either polymer photodegradation or conversion of the dye to a non-emissive species. In view of the deficiencies in present day solid state dye lasers, dyes having greater TPA cross-sections and solid dye laser systems more resistant to photodegradation are desirable.
Optical Limiting
Optical limiting effects and devices are becoming increasingly important in the areas of nonlinear optics and opto-electronics. In particular, these materials are used in protective eyewear against intense infrared laser radiation exposure, in windows for sensitive detectors, and as stabilizers for laser beams used in optical communications and data processing by reducing beam intensity fluctuation. For optical power limiting applications, the material must have a low absorption of light at low intensity and must show a decrease of transmissivity at high intensities so that, at sufficiently high intensities, transmitted intensity levels off. There are several different mechanisms, such as reverse saturable absorption (“RSA”), two-photon absorption (“TPA”), nonlinear refraction (including all types of beam-induced refractive index changes), and optically induced scattering, which could lead to optical limiting behavior (Tutt et al.,
Prog. Quant. Electr
. 17:299 (1993)). A number of research studies of optical limiting effects, related to TPA processes in semiconductor materials, have been reported (Walker et al.,
Appl. Phys. Lett
. 48:683 (1986); Chang et al.,
J. Appl.Phys
. 71:1349 (1992); Van Stryland et al.,
Opt. Eng
. 24:613 (1985); and Hutchings et al.,
J. Opt. Soc. Am
. B9:2065 (1992)). However, the two-photon absorption cross section of these materials is quite weak, which limits their applicability in many optical power-limiting situations. The search for new materials having larger TPA cross-sections and stronger optical power-limiting properties in the infrared continues.
Infrared Beam Detection
Since infrared light is not visible to the human eye, focusing, aligning, and adjusting the shape of infrared beams, particularly infrared laser beams, requires the use of a device which permits the user to visualize the beam. Conventional, commercially available infrared detection and indication cards, manufactured by Kodak and Kentek, respectively, typically employ a material which operates on thermal release effect principles, becoming visible when exposed to infrared radiation. Because of the nature of the visible effect, i.e. a color change in the surface layer of the card, the card is opaque and must be viewed from the side from which it is exposed. This is frequently inconvenient and makes beam alignment difficult, if not impossible. Furthermore, the commercially available detection sheets exhibit saturation at intensities lower than those used in most infrared laser applications. Consequently, these cards are of little value in assessing the intensity or intensity profile of the beam to which they are exposed. Moreover these detection cards have undesirably short lifetimes, especially when used to detect intense infrared laser beams, and degrade non-uniformly and unpredictably, making their use unreliable. The nature o
Bhawalker Jayant D.
Cheng Ping Chin
Pan Shan Jen
Prasad Paras N.
Frech Karl D.
Nixon & Peabody LLP
The Research Foundation of State University of New York
LandOfFree
Two-photon upconverting dyes and applications does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Two-photon upconverting dyes and applications, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Two-photon upconverting dyes and applications will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2897821