MXPA96004164A

MXPA96004164A - Optical sources having a strongly scattering gain medium providing laser-like action

Info

Publication number: MXPA96004164A
Application number: MXPA/A/1996/004164A
Authority: MX
Inventors: M Lawandy Nabil
Original assignee: Brown University Research Foundation
Priority date: 1994-03-18
Filing date: 1995-03-06
Publication date: 1998-10-23

Abstract

A gain medium is comprised of a multi-phase system wherein:a first phase is an electromagnetic radiation emission phase;a second phase is an electromagnetic radiation scattering phase;and a third phase is a transparent matrix phase. By example, the emission phase may consist of dye molecules, the scattering phase may consist of high contrast particles, and the matrix phase may consist of a solvent such as methanol. In some embodiments of this invention the emission and scattering phases may be the same phase, as when semiconductor particles are employed. A smallest dimension of a body comprised of the gain medium may be less than a scattering length associated with the scattering phase. It is shown that nearly thresholdless laser behavior is observed in strongly scattering optically pumped dye-methanol solutions containing colloidal TiO2 or Al2O3 ruby nanoparticles. The emission from the high gain colloid exhibits a slope change in the linear input-output characteristics above a critical pump pulse energy. The change in slope is accompanied by a spectral line narrowing with a bichromatic spectrum appearing at high pump energies.

Description

OPTICAL SOURCES THAT HAVE A STRENGTHLY DISPERSING GAIN MEANS PROVIDES LASER-LIKE ACTION CROSS REFERENCE TO A RELATED PATENT APPLICATION 5 This patent application related to a co-pending patent application Series No. 08 / 210,356, filed on Mar. 18, 1994, entitled "Opt.cal Gain" M dium Having Doped Nanocrystals of '-.emiconductors and Pliso LO Optical catterers ", by Nabil M. Lawandy (Summary of the Representative No. 317-9 5033-NA).

FIELD OF THE INVENTION This invention relates generally to sources d < -i , elect rornagnet energy 1 ac, in particular, the invention relates to highly monochromatic sources (narrow spectral line width). ;, (1) BACKGROUND OF THE INVENTION t: n a publication entitled "Generation of light by scaUermg medium? ith nega-t ive i sonance absorpr ion", v.

Phys., 3ETP, Vol. 26, No. 4, flbp 1 1968 (pp. 835-839),. r ..

I etokhov presents a theoretical analysis of the generation of light by means of dispersion with absorption of negative resonance /) gain. This analysis requires that an average free path of phot n (nß) be much smaller than all dimensions (R) of the active scattering region (equation l) In a discussion of a condition for a generation threshold, a example for an optically excited spherical distribution of ruby particles (? = 7 X 10-5 cm) with radius 2 X 10-4 Cm, e. The critical radius resulting from the region is shown to be approximately 4 rrtm. Letokhov also provides a theoretical analysis for dispersion particles that are distributed in a gaseous medium with negative absorption, such as a mixture of He-Ne or He-Xe gas excited by an electric discharge. It is said that the dispersed particles perform a non-resonant realization, while the gaseous active medium effects resonant amplification. The critical effective radius for such gaseous media is said to be approximately 1.8 cm. A continuous decrease in the human performance is predicted. Reference is also made in this regard in a previous theoretical paper by Letokhov, "St mulated emersion of an ensernble of scattering parts with negative absorption", 7hETF Plasma 5, No. 8, April 15, 1967, (pp. 252-265), wherein the dimensions of the medium are given as R > > nß > > ? where, as before, R is the dimension of the medium, n8 is the average free path of a photon due to scattering, and? is the wavelength of the photon. Reference is also made to a publication by Irnbartsurnyan R.V., Basov N.G., Kryu ov P.G. and Letokhov VS in "Progress in Quantum Electronics" (ed. Sanders JH 8 Stevens KUH) 109-185 (Pergamon Press, Oxford, 1970), where a theoretical presentation is made on pages 152-153 of a case where the free path of a phot n due to scattering, nß - 1 / QßNo, the average dimension of the region occupied by a cloud, R, and the wavelength of the emission X satisfies the ratio R > > í) ß > > X, and where the average distance between the scattered particles is much greater than the wavelength. A clear problem in Letokhov's approach is that all the dimensions of the medium must be much larger than the length of the dispersion. For example, it may be required that each dimension of the medium be of the order of one cent. These dimensional requirements would impede the use of the medium for many valuable applications of high spatial resolution. For example, a particularly valuable application that could not be achieved according to Letokhov's teachings is the formation of a thin layer, cover, or body that includes the means of gain. Another example is a sphere or cylinder whose radius is comparable to the length of the dispersion or smaller. A further problem is the requirement to provide dispersed particles in a gaseous medium, particularly one that is excited by an electric discharge. This may be difficult to achieve in practice, and can be impractical for most applications. Reference is also made to an article entitled "Generation of stirred noncoherent radiation in light-scattering media exhibiting chernical reactions", Sov. 3. Quantum Electron. 12 (5), May 1992, (pp. 588-594), where I.. Tzrnailov and others propose that a real irradiation resulting from dispersion be used to achieve light emission in a dispersed reagent. The feasibility of chemically pumping the laser is estimated based on calculations of the heterophase combustion of a drop of fuel in an oxidizing atmosphere. The reactions between NO and O3, Ba and S2CI2, and Ba and N2O are specifically calculated. A device based on this approach, if it were possible to do so in a practical sense, would seem to be limited to a narrow scale of special applications. Reference is also made to the following three patents of the United States, all of which describe and claim inventions that were made by the inventor of the invention described in this patent application: US Pat. No. 5,157,674, issued on October 20, 1992, entitled "Second Harrnonic Generatjon and Self Frequency Doubling Laser Materials Cornprised of B? Lk Germanosil 1 cat e and Aluminosilicate Glasses"; U.S. Patent No. 5,233,621 issued August 3, 1993, which is a division of the above patent; and U.S. Patent No. 5,253,258, issued October 12, 1993, entitled "Optically Encoded Phase Matched Second Harmony Generation Device and Self Frequency Doubling Laser Material Using Semiconductor Microcrystallite üoped Glasses".

BRIEF DESCRIPTION OF THE INVENTION The above and other problems are solved by a gain means which, according to the first aspect of this invention, is an inultiphasic system wherein: a first phase is a phase of emission and amplification of electromagnetic radiation; a second phase is a phase of dispersion of aggregating elective radiation; and a third phase is a transparent matrix phase. For example, the emission phase may consist of dye molecules, the dispersion phase may consist of AI2O3 particles, and the matrix phase may consist of a solvent such as methanol. In some embodiments of this invention, the emission and dispersion phases may be the same phase, as when using semiconductor particles. A smaller dimension of a compressed body of the gain medium may be smaller than a dispersion length associated with the dispersion phase. In a further embodiment of this invention, the matrix phase has gain, for example, the PPV polymer, and the particles are aggregated for dispersion purposes.

In a specific embodiment of this invention, laser-like activity is generated in an excited nitroethanol solution containing a dye, for example, rhodinoline, and nanoparticles of high contrast ratio, such as T1O2 or 01203. This gain medium It exhibits many of the properties of an efficient laser source, and has an input-output behavior near its threshold. A laser-like activity is intended to encompass a condition in which a well-defined excitation causes the output line width of the emission to be reduced. Significantly, the directional restrictions inherent in the prior art are solved. It is shown that laser-like activity occurs when the gain medium has a dimension that is only slightly greater than, equal to, or even smaller than the scattering length of the photons in the medium. This is in clear contrast to the dimensional requirements of Letokhov et al., As previously described. In an embodiment of the invention, laser-like behavior is achieved almost without threshold in a dye-ethanol solution. optically pumped was a dispersant containing colloidal nanoparticles of T1O2 or AI2O3. The emission from the high gain, optically pumped colloidal medium, exhibits a slope change in its linear input characteristics - going above a critical pump pulse energy. The change in slope is accompanied by a significant decrease in the output spectral line width, with a bichromatic spectrum that appears at high pumping energies with some dyes. It was found that the excitation of the colloidal medium with pulsations of 80 μsec to 532 nrn results in a shorter emission than a resolution time of 300 picoseconds of an optical detection system, thus confirming the occurrence of laser-like behavior. only f1 uorescent behavior e.

BRIEF DESCRIPTION OF THE DRAWINGS The aspects described above of this invention are made clearer and more fully described in the following detailed description of the invention, which is intended to be read in conjunction with the figures of the accompanying drawings, wherein: Figure 1 graphically illustrates 3 different emission spectrums that were obtained by using (tracing "a") a color-ante uro excited by a source of excitation; (trace "b") the dye in combination with dispersed particles below a threshold excitation, and (trace "c") the color-ante in combination with dispersed particles above the excitation threshold. Figure 2 illustrates an integrated emission graph of wavelength - not a function of pumping pulse energy for the pure-color solution of figure 1, trace "a", (hollow circles) and the coLoidal dye solution of T1O2 nanoparticles (2.8 x 10 * o / oin3) of Figure 1, stroke "b" (full circles). Figure 3 illustrates a peak emission as a function of pumping pulse energy for four different nanoparticities of T1O2. Specifically, nanoparticities of 1. x 109 / crn3, 7.2 x lQ9 / c3 n3, 2.8 x I0io / cm3, and 8.6 x 10 * 1 c3 are shown with solid circles, diamonds, squares and triangles, respectively. The insert shows the data on a logarithmic scale for a density of nanoparticles of 2.8 x 10o / crn3, Figures 4a-4c illustrate an emission line width as a function of pumping pulse energy for three different densities. of nanopart 1 T1O2 cells. More specifically, Figures 4a-4c correspond to the densities of 5.7 x 109 / cm3, (solid circles), 2.8 x l / cm3, and 1.4 x 10 / cm3, respectively. The hollow circles in Figure 4a represent the width of 1 mea of the emission of the pure dye solution of Figure 1, trace "a" as a function of pumping pulse energy. Figure 5 is a graph of intensity versus wavelength for a gain medium consisting of tan 440 and dispersion particles. Figures 6a-6c show the response of the dye solution of figure 1, trace "a", (figure 6a) and the solution of T 2 / dye of figure 1, trace "b" to a course of pulsations of 80 picoseconds of extension in which figure 6a shows the response of pure color-ante to the highest pumping energy, while between figures 6b and 6c show the response of colloidal nanoparticle coloring solution (2.8 x 10i) ° / c? N3) of T1O2 at low pumping energies (1.2 x 10-2rnJ /? Ulsac? On) and high (1.2 x 10-irnJ / pulsation), respectively. Figure 7 is a simplified diagram of a system that includes a mechanism that provides laser-like behavior and from which the data shown in Figure 1-6 was generated. Figure 8a is a graph of the dimension of the critical transverse aperture as a function of color-ante concentration; Figure 8b is a graph of peak intensity versus size of aperture (microns) for a gain medium having a dye concentration of 3.5 x L0-3 M; Figure 8c is a graph of emission line width (nano-lines) versus aperture size (microns) for the gain medium having a color-ante concentration of 3.5 × -3 ri; Figure 8d graphs the intensity of emission against the wavelength for a thin monolithic solid sample (0.5 nm thickness) of the gain medium. Figures 9a and 9b illustrate a modality, each of this invention wherein the means used to form a plurality of pixels of an exposure unit, the pixels being scanned by a laser during use. Figure 10a illustrates an embodiment of this invention wherein the medium is used to pair a plurality of regions on a surface of a transparent substrate to simultaneously provide a plurality of different output wavelengths in response to a length of entry wave. Figure 10b illustrates a multi-leg configuration of a plurality of substrates carrying gain means. Figure 11 illustrates one embodiment of this invention wherein the medium is encapsulated within a small fer-a. Figures 12a and 12b illustrate each embodiment of the invention wherein the medium is employed to form a plurality of regions each of which emits different wavelengths of output in response to a wavelength of in band. Figures 13a-13f illustrate one embodiment of this invention, each, wherein the medium is contained within a portion of an optical fiber or catheter to provide a desired wavelength in a localized region. Figure 14 illustrates an embodiment of this invention that shows a system having a screen that is selectively coated with the medium, and a scanner l to selectively cause the medium to emit a well-defined desired wavelength.

Figures 15a and 15b illustrate one embodiment of this invention, each in which each of a plurality of objects includes a cover comprised of the medium, a laser-for illumination of the objects and a detector for detecting the emitted wavelength. for the covers. Figure 16 illustrates an embodiment of this invention wherein the medium is used to fnd a cue, specifically a bar code, on a surface of an object. Figure 17 illustrates an embodiment of this invention wherein the medium is applied as a cover (solid or solid) to an object capable of internally transmitting a wavelength or wavelengths that are emitted by the cubicle. Figure 18 illustrates an embodiment of this invention wherein the medium is used to overconvert a first wavelength in a second shorter wavelength. Figure 19 illustrates an embodiment of the invention wherein the medium is used as a cover over the lenses of a pair of glasses to provide eye protection against being-. Figures 20a-20c illustrate the use of the medium in a non-linear Rarnan scattering mode. Figure 21 describes a particle including the gain means being accelerated due to a force exerted by an input pumping beam. Figure 22 is a cross-sectional view, not to scale, of an electrically driven light emitting device, based on polymer, which benefits from the amplification and deviation of the emission that are made possible with this invention. Figure 23 is a cross-sectional view, not to scale, of a laser diode embodiment of this invention, wherein the gain means is applied as a cover to an emission front of the laser diode to provide a similar emission to the laser at a wavelength that differs from the fundamental emission wavelength of the laser diode. Figure 24a is an elevation view, not to scale, and Figure 24b is a top view, not to scale, showing an embodiment of this invention wherein the gain means of this invention is used to pump a second gain medium. , such as a coLorante solution or a ser-rod, to modulate a pump wavelength to the second gain node.

DETAILED DESCRIPTION OF THE INVENTION To describe in detail a number of novel embodiments of this invention, a description is first made of the experimental results that clearly illustrate the novel properties of a modality of the means of this invention.

Experimental description: Experiments were carried out in solutions containing a concentration of ix 10-3 to 2.5 X iQ-3 of dye of stem ma 640 in methanol with different amounts of nanoparticles of T1O2 (rutile) or of Al2 3 3 f e e) . The T1O2 particles have a mean diameter of 250 n and the AI2O3 particles have a diameter of either 280 nrn or 33 nm. T1O2 particles were covered with a layer of AI2O3 to prevent flocculation. Based on particle sizes and densities, it was determined that these colloids should exhibit settling times of 14.2 hours, 6.6 hours and 882 hours per one length of 1 cm, respectively. These times are considerably larger than the experimentation times of 30 minutes to 1 hour .. In addition, the < - »Total surface area L available for the absorption of the dye molecules to the nanoparticles, specifically, it was found that the T1O2 particles have an available surface area of 13.4? N2 / gram pair-to accommodate- The molecules of coloring. This value indicates that at a particle density of p-1010 / crn3, about 1% of the dye molecules of a dye solution of 2.5 x 10_3M can be accommodated on the surfaces of the nanoparticles. This upper limit effectively eliminates the possibility that effects with the surface play a significant role in the observed properties similar to the colloidal solution. The optical dispersion properties of the nanoparticles were in the Mie regime. The dispersion of the cross sections at the peak wavelength in the emission of the dye of about 617 nm was calculated using the full Wed solutions and found to be too small to exhibit any morphological resonance. It is believed that this is primarily due to the small size parameter, x = ka, where is the emission wave vector in methanol and a is the particle radius. Using refractive index values of 2.62, 1.77 and L.33 for T1O2, AI2O3 and RN, the cross-sectional dispersion values of 1.86 x 10-9 c 2, 1.13 x I0_9cr2 and 1.0 x 10-13 cm2 were determined for the T1O2 and the two particle sizes of AI2O3 respectively. As described in Figure 7, a transparent cell 10 (at the wavelengths of indices) had a solution 12 with nanopart 1 colloids in ethanol impregnated with rhodamine 6-10 perelorate at concentrations on the 10-3 M scale. The cell 10 theme nominal dimensions of lcx 1 cm x 1 cm. It should be noted that these dimensions of the cell were selected for convenience to carry out the experiments. That is, and as will be described later, these cell dimensions are not to be construed as a limitation in the practice of this invention.

L5 Solution 12 was optically pumped off-axis by 532 ntn radiation polarized 1 meal from a laser 14 of duplicate frequency Nd: YAG at 1064 m. Experiments were performed with a Q-switched laser that predicted only 7 nanosecond pulses, or you in a closed-mode, Q-shaped laser that produced a ren of 125 nanoseconds in length that contained 9 beats of 80 pico-seconds in length. It was found that the 532 nrn radiation had a small serial penetration depth of 50 microns within a 2.5 x 10-3 M solution of pure dye in methanol, making it smaller than the shorter optical dispersion lengths (ls) used. in any of the experiments. It was determined that the laser spot area 16 on the incident front 10a of cells 10 was 2.5 x LO-2 c for 7 nanosecond pulses, and of 7 85 x 10-3 c 2 for the excitation of 80 ?? Seconds The measurements using the long pulses were made at a repetition rate of 5 Hz, although pulse measurements of 80 picosegments were made at a change rate Q of 25 Hz. These low repetition rates were used to avoid any dye degradation effect, and are not a limitation in the practice of the invention. The maximum energy per pulse for the experiments was approximately 10 rnJ and 0.12 rnl for the long and short pulsations, respectively. The output from the front 10a of the cell 10 was collected using a lens 18 and was "sent to an inultant analyzer optical channel 20 with a CCD arrangement cooled with liquid nitrogen 22, as well as through a monochromatic spectroscope 24 to a fast photodiode 26. and oscilloscope 28 that had a global resolution time of 300 picoseconds.

Example: A first sene of experiments was performed using pulses of 7 nanoseconds in length pumping "- Rhochin perchlorate 640 at a concentration of 2.5 x 10_3 M in methanol solution in cell 10. The excitation of the pure color-ante solution resulted in the spectrum shown in Figure 1," a "grade. The spectrum exhibited a main peak at 610 nm with a highlight at 640 nm This spectrum was found to remain constant for the entire scale of pumping pulse energy up to 10 nm. The wavelength of the integrated fluorescence (or one solution of the pumping energy) exhibited a saturation behavior with a saturation energy of 0..26? N3 and is shown by the open circles in Fig. 2. This saturation energy together with the size of the point and the duration of the pumping pulsation agree with the saturation intensity given by Ie - hv / o ts P - 0.7 MU / cm2, where o is the cross section of Absorption of pumping at 532 nm (oP - 1.33 x 10-16 crn2 and r P is the spontaneous life time Si -> So (4 nanoseconds) Pumping experiments were carried out is in the ethanol-dye solution containing 2.8 x 10i / crn3 of the T1O2 nanoparticles.The results of these experiments were markedly different.The spectrum in the lower excitations exhibited a line width of 76 nrn, compared to the 36 nrn of width of the pure dye solution When the energy was increased As a result of the excitation pulsations, the unpolarized emission at X -617 n grew rapidly and was reduced as shown in Figure 1, trace * - b. By increasing the energy of pumping even more, a chromatic spectrum is observed. This spectrum bicrornat 1 co was found to be similar to that reported for the strong-ring eyed laser dye. The emission of 640 n was observed only in thicker cells of 100 microns, and is associated with the stimulated emission in a weaker vibration transition. The flatness of solid circles in Figure 2 shows the integrated emission wavelength (not a function of the pumping energy.) It is important to note that the colloidal solution containing the T1O2 nanoparticles does not exhibit the strong saturation behavior observed in the Pure color-pure solution.Fisto, the use of the medium of this invention provides a non-saturable source of highly monochromatic optical energy.It is also important to observe the dependence of the emission peak? - 617 nin on the pumping energy for different nanopart densities shown in Figure 3. More specifically, Figure 3 shows a well-defined threshold for the change in the efficiency of the slope at 617 n for all concentrations of the particles. a logarithmic scale, the result is the characteristic S-shaped curve par-a 5 laser behavior shown in the insert of figure 3. The curve exhibits a very soft curvature characteristic of laser behaviors with almost no threshold, which approximates a straight line when all modes of spontaneous emission are capable of emitting laser light. The analysis of this data of linear form reveals that at the same pumping energy where a change in slope is observed in the input / output behaviors, the line width of the edition decays rapidly to 4 n Figures 4a-4c show graphs of the total width to a maximum emission mean as a function of the pulse energy of the pumping for three different concentrations of T1O2 nanoparticles. Figure 4a also shows the width of the pure-color line as a reference (shown in open circles). The results plotted in the figure clearly show the laser behavior of almost constant state that takes place in medium 12. It is important to note that this laser behavior of almost constant state occurs in an optically walked solution that is not located within a structure of ? f resonant quality, as is the case par-a laser system of conventional dye.

The data collected in various concentrations of nanoparticles was used to determine the relative dependence of the slope efficiency, €, on the laser concentration of the particles. The results revealed a linear dependence of eop up to a critical value pc = 5 x 10io / crn3, where when increasing the particle density there is no appreciable increase in the efficiency of the slope pair-to the output of light emitted to X 617 n. Similar results are observed with the other two particle density densities which correspond to the comparable mean free dispersion paths. In addition, it was found that the dispersion efficiency was also dependent on the dye concentration on the scale from 1 x 10 -3 M to 5 x 10 -3 M. In a further group of experiments, the light emitted from the LO cell was sent through the monochromatic spectacle 24 to the fast photodiode 26 and oscillated theoopium 28 to determine the temporal characteristics of the emission at different wavelengths. Figures 5a-5c show the recorded plots for excitation of 3 rnJ per pulse (7 nanoseconds of lar-go) of the pure dye. The intense emission of 617 nm and the emission peak of 640 nm. These results indicate that the pure dye and the emission of 640 nrn both have a peak after the pumping pulse, while the radiation of 617 nrn reaches a maximum before the peak of the pumping pulse. The excitation with a pulse train of 80 pi sequesters also revealed a threshold behavior in the temporal characteristics of the colloidal colorant solution / nitroethanol / nonoparticles 12. When the pumping pulsation energy was below that required for the appearance of the laser action, the emission peak at 614 nrn exhibited a 4 nanosecond drop in length at all pumping energies that was identical to that observed in the pure dye solution. In addition, a larger antecedent signal was observed since the pulses arrived every 13. US nanoseconds, a rate of repetition of pulsation that scarcely allowed the relation of the excitation. However, when the pumping pulse energy was increased beyond the threshold point an acute peak appeared that was shorter in duration than the 300 picosecond resolution of the oscilloscope 8. An additional increase in energy resulted only in the sharp peak, and in an almost complete recovery between the pulsations in the closed node and the change gear Q. These results are shown in the oscilloscope traces of figure 6. The data that were previously presented with reference to figures 1 -6 clearly show that laser-like activity occurs in medium 12. This can be established because: a) the observed change in slope to a well-defined pumping energy; b) the linear input-output behavior below and above the threshold; c) the spectral mea, narrowing above a well-defined energy of oombeo; and d) temporary compression over a threshold excitation. The comparison of these data with the results obtained for the mixture of the pure dye reinforces the determi- nation of the laser action. Figure 8a is a graph of critical cross-sectional dimension as a function of dye concentration; Figure 8b is a graph of the intensity of the tic against the size of the aperture (microns) for a means of "-gang having a dye concentration of 3.5 x 10_ 3; - Figure 8c is a graph" I read the line width of the emission (manometers) against the size of the aperture (microns) for the gain medium that has a dye concentration of 3.5 x 10-3 n, and figure 8d graphs the intensity of the emission against the wavelength f> for a thin solid monolithic sample (0.5 nm thick) of the gain medium .. It can be seen that an emission from the gain medium 12 is possible over a region having at least one dimension ( size (He aperture or transverse dimension) which is less than or of the order of the associated dispersion length of the medium 12. This is an important aspect of this invention, in which it makes possible a wide range of applications where it is desired to provide the medium 12 within a small volume, or as a cover or thin layer. The following analysis is presented to aid the qualitative understanding of this invention. Although it is not intended to limit the scope of this invention by theory: >; ". > Now it will be presented, this theory is believed to be accurate and consistent with observable facts and accepted scientific principles. The explanation for the observed behavior similar to the laser of the optically pumped colloidal gain medium is not fully understood to date. A first look is to think in terms of button diffusion as to provide a type of real non-resonant activation for the high gain dye. One of the main problems in evoking the method of diffusing light as the origin of the pseudo-cavity makes evident the detailed experiments before it is that the effect requires that the small dimensions of the medium of dispersion be larger compared to the length of optical dispersion. However, in the case of the experiments detailed above, the length of diffusion at the laser light emission wavelength was typically of the order of 200 microns, requiring that each dimension of the sample be in the order of several millimeters -a that the po of button diffusion is a nificative concept. As was described above in relation to Figures 8a-8d, the similar behavior-to-be was observed with samples which were 100 microns thick. In a subsequent series of experiments it was found that the line width drop could be observed in thickness - in cell thicknesses as small as 30 microns, or one sixth of the length of the dispersion. These results suggest that the diffuse type model predicted by Letokhov in its simplest form, is inadequate to explain the activity similar to the average gain laser 12. Experiments with ours have each dimension smaller than the length of the dispersion, and which is the refractive index matched at the borders, it also exhibits laser-like behaviors. The reduction of the line width within a region having a dimension that is less than the length of the dispersion of medium 12 is believed to be due to a previously unrecognized or unrecognized type of radioactive decay of a population of dye molecules . Conventionally, a population of dye molecules exhibits an inconsistent path, where the total power of the radiation and it is the sum of the potencies of each dye molecule, or power equal to S i. The effect observed or in the medium 12 of this invention rather seems to exhibit the operation of a coherent decay mecha- nism in which the power emitted is well given by (SA_) 2"For example, for a conventional two-molecule system dye The total emitted power is 2, while for the medium 12 of this invention the total emitted power is 4. The result is an emission of a region, which has a small dimension of only hundreds of centimeters or less, of substantial light monochromatic light that has a high intensity or brilliance. Having thus described the physical and optical characteristics of the means 12 of this invention, now a description will be provided of a number of embodiments of this invention employing the means 12. In some of these embodiments, the means 12 is provided. as a cover or layer, similar to a paint or cream. For certain of these embodiments, the dye molecules and the dispersed particles are provided in conjunction with a transparent binder (a Wavelengths of interest) or mat material, such as a polymer. That is, dye molecules and scattered particles are immobilized within the matrix. Also, in the following description it should be understood that the teaching of this invention is not limited to use only with the dye molecules. For example, the invention may also be practiced with small particles of a semiconductor (such as CdSe) of a type suitable for emission of light in response to optical input or electrical energy. In this embodiment the semiconductor particles can be used with the dispersed particles described above or they can themselves serve as dispersion particles in a later embodiment of this invention the gain material and the matrix are one and the same, and they have scattered particles throughout the matrix. For example, the gain / matrix material is composed of the polymer such as polyphenylene vinyl ina (PPV), and the dispersed particles are nanoparticles of AI2O3 and / or T2 which are dispersed with the PPV. Also for example, the CdSe particles may be provided in the PMMA polymer, or PPV particles may be provided in PMMA. Figure 9a illustrates an embodiment of this invention wherein the means 12 is used to form a plurality of pixels of an exposure apparatus, the pixels being scrutinized during use by a l. More particularly, an exposure system 30 includes a pixel plane 32 comprising a transparent substrate 33 having a plurality of pixels 32a formed on or within a surface thereof. Each pixel 32a may be comprised of a plurality of subpixels 32 of each of which is comprised of the medium 12. Each subpixels 32b may have dimensions of one hundred percent or more or less. The medium 12 is provided with, for example, only 6 subpixels each containing a different type of dye molecule in combination with dispersed particles. In the example shown, two of the regions (Rl and R2) emit wavelengths within the network portion of the spectrum, two of the regions (Gl and G2) emit wavelengths within the green portion of the spectrum, and two of the regions (Bl and B2) emit wavelengths within the blue region of the spectrum. In one embodiment an LCI array 34 is posi cloned adjacent to a surface of the screen or pixel plane 32. The LCD array 34 is controlled by a control signal to selectively allow the radiation emitted from one or more of the subpixels 32b pass through an observer. Se 2b provides a scanning laser 36 to scrutinize pixel array 32 under the control of a video scrolling signal. The scrutiny of the pixel array causes each of the non-saturable subpixels 32b of a scrutinized pixel 32a to emit a narrow band of wavelengths that has been determined by the constituent dye molecules. Due to the presence of the scattered particles, the output of a given sub pixel 32b appears to an observer as a small point of bpLLan, essentially monochromatic light. The Light is not collimated due to the scattering nature of each pixel, and thus is not innate to a narrow scale of angles. Co-operatively with the subpixel illumination s 32b, one or more elements of the LCD array 34 is selectively "open" to allow the wavelength emitted from one or more of the subpixels 32b to pass to the observer. When the pixel array is scrutinized at video speeds the visual effect is the formation of a bright-color image without saturation, thus allowing the view to a distance. It should be understood that at least 6 subpixels 32 can be employed for a given pixel 32a. The use of 6 subpixel allows two different shades of each primary color (for example 620 nrn and 640 nrn for red) to be generated, and also a hexagonal subpixel pattern to be formed which provides an efficient packing density. 2 ? In an additional mode, three subpixels are provided, for red, green and blue. In another modality, two sbpixels are provided, for example ro and green, and the pixels are scanned with a laser-which provides the blue color. The laser 36 can be positioned to illuminate the array of pixels from the back side, or they can be positioned to illuminate the array of side pixels, thus reducing the overall depth of the exposure. Figure 9b shows a portion of a substrate 33 having a plurality of pixels 35 disposed on a surface thereof. The pixels 35 can be deposited in a liquid form and subsequently tattooed or dried. Each pixel is comprised of the optical gain means of this invention. In the embodiment of Figure 9b the plurality of light guides 37 are provided on a surface or within a surface of the substrate 33 and are provided with a first wavelength of a laser (not shown) which is disposed at Length of one edge of the subst. If the light guides 37 are optical fibers, a break of the input wavelength is used to optically pump the adjacent pixels. If the Light Guides 37 are rather waveguide type structures, then evanescent radiation coupling is employed outside the wave paths to optically pump the pixel s dyacent is. In a further embodiment of the invention, each of the pixels 35 can be coupled to an associated thin film transistor (TFT) which injects, when energized, load carrier within the pixels. In this mode the charge carriers are used as an excitation source to cause the pixels to emit the desired wavelengths. In all of the embodiments of an exposure apparatus, the pixels operate so that they are substantially non-saturable and so that the electromagnetic radiation comes out.

"Within a narrow band of wavelengths." Co or such, the pixels of this invention are easily distinguished from the conventional phosphorous pixels commonly used in televisions, video monitors and the like. This invention wherein the medium 12 is used to form a plurality of regions on a surface of a transparent substrate to simultaneously provide a plurality of different output wavelengths in response to an input wavelength. cross section view of the structure 40 comprised of transparent substrate 42 having one or more regions of layers 44a-44d each of which is composed of medium 12. Each layer 44a-44d contains dye molecules selected to provide a wavelength output desired (X? -? v) in response to an input wavelength (i ") provided from a suitable laser source (not shown) If the layers 44a-44d are simultaneously illuminated then the plurality of wavelengths output are issued simultaneously.A valuable application for structure 40 is to provide a plurality of different wavelengths to a surface of the skin to eliminate undesirable skin pigmentations such as port wine stain and tattoos., the layers 44a-44d are formed in the shape of the area of the pigment to be removed, with each layer containing for example, a molecule of dye or semiconductor particles selected to emit a wavelength that is strongly absorbed by the underlying pigment. Preferably, the substrate 42 is made flexible so as to conform to the contour of the body part. The presence of the substrate 42 is optional, although it is useful when first stitching the layers 44a-44d into a desired pattern, and also to avoid contact of the medium 12 with the skin. It is also within the scope of this invention to use a low diffusion angle in order to mix the wavelength emitted with another, instead of providing well-defined spatial regions each emitting a very narrow specific band of wavelengths. It is also within the scope of this invention to stack two or more gain means that carry substrates one over the other in a multi-layer configuration. In this case, the emitted wavelengths of the upper substrates can level transparent non-obstructed transparent portions (at wavelengths of indices) of lower substrates; or a wavelength emitted from a higher substrate can be used to pump a region of gain medium onto a lower substrate. These two cases are generally shown in Fig. 10b, where Xi and X2 pass through the multilayer structure, and where 2 is used to optically pump the lower gain medium region to generate X3. Figure 1 illustrates an embodiment of this invention wherein the medium is encapsulated within a small 5U sphere. For example, the sphere 50 has a diameter of the critical diameter of the layer, the sphere 50 has an outer surface 52 and an internal region 54 that contains the medium 12. In response to illumination with a first wavelength the medium 12 it emits the second wavelength as determined by the means of consis- tent gain in combination with the corresponding parts. In use, a large number of spheres 50 can be used which can be used to cover a surface such as, for example, a surface on or adjacent to a road or track. In response to the laser illumination, that portion of the surface having the spheres 50 emits a bright and substantially monochromatic light thus making a particular portion of the surface and slender easily accommodated or to a suitable detector. In this regard, the medium 12 may contain dye molecules that respond to infrared or near infrared wavelengths that can easily penetrate the haze and rain.A suitable dye for this application is known in the art as TR 144. it is within the scope of this invention to suspend the small gain medium bodies within the atmosphere to be used, for example, as an atmospheric marker for adaptive optical calibration, in which case the small gain media bodies can be optically pumped by a laser-based or non-earth-based laser source It is also within the scope of the invention to pump the gain medium with a natural L pumping source, such as the alba.It is also within range of this invention pump the gain medium with a magnesium bulb.Also according to this embodiment of the invention, the spheres 50 can be poured over water so that they leave a detectable trail behind a ship. This allows, for example, that an aircraft carrier leaves a detectable track that can be followed by a r-etorno airplane. In this example, each airplane is equipped with an L-source suitable for illuminating the surface of the water and with a suitable detector, such as an image array TR, for detecting the emitted wavelengths. The particular choice of a wavelength for a given day or mission can be selected to provide a degree of security. This is, the airplane expects to detect a specific wavelength and may be provided with a corresponding filter or detector for the expected wavelength. In addition, in this regard, the medium 12 can be used as a cover dispensed, for example, by an aerosol or a liquid to identify targets of trust ordinance having a sensor that is sensitive to the wavelength emitted. In general, means 12 finds use in "friend or enemy" detection systems. For example, in a battlefield situation all vehicles are provided with a portion covered with medium 12 containing molecules of dyes selected to emit a predetermined wavelength. When illuminated by a laser source only those vehicles that have the cover will emit the expected wavelength. Any vehicle that does not emit a length of light when it is illuminated or does not emit the predetermined wavelength will be suspected. It may be appreciated that the medium 12 may be provided in a low cost manner as a cover applied directly to the vehicle. an object, or a changeable portion of the object such as a removable panel. For example, a vehicle can be provided with a group of plastic panels that are easily installed on an external surface, with a particular pan being specified for use for a predetermined period of time. Each panel may include a cover of gain medium with scattered particles, or may itself be a body comprised of the gain medium and scattered particles (eg ppv and T1O2). Although the sphere 50 of Figure 11 is shown to contain a volume of the medium 12, it is within the scope of the invention to construct the sphere from a polymer that is impregnated with the molecules of the desired dye and the dispersed particles. Alternatively, the spheres can be small particles of a polymer such as dispersed particles containing the ppv. It is also within the scope of the invention to impregnate a porous material such as certain glasses and sun gels with the gain medium. It is also within the scope of the invention to employ a refractive constraint index between, for example, a solution of dye molecules contained within the pores and interstices of a host material, and the surrounding host material itself as the dispersion phase. . In this case the color-ante molecules provide the optical gain phase while the host material forms both the co matrix and the dispersion phase. According to one aspect of this invention, at least one dimension of a host / dye body can be made very small (ie, dozens or hundreds of fibers in thickness- or diameters) while exceeding similar activity to it. when it is excited properly. Figure 12a illustrates an embodiment of the invention wherein the means 12 is employed to form a plurality of regions 62a-62d on a surface of a translatable transposable substrate 60 to provide one of a plurality of different output wavelengths (? 2_? S) in response to an ent -ada wavelength (? I). in the illustrated embodiment the substrate 12 has an axis of rotation of odo that a portion having the regions 62a-62d is positioned in the output ace from a laser 64. The wavelength emitted from one of the given regions that is positioned within the beam is coupled within an optical fiber 66 having an input coupler 66a and an output coupler 66b. Optically coupled to the salt coupler 66b is a radiation receiver 68. A controller 70 is mechanically coupled (70a) to the substrate 60 by rotation of the substrate 60 to provide different wavelengths to those emitted to the receiver 68. The controller 70 is also electrically coupled (70b) to the receiver-68 to inform the flue receiver 68 Wavelength is currently being emitted from the substrate 60. This arrangement allows the construction (ie a secure communication system, where the laser 64 is modulated with information to be transmitted and wherein the emitted wavelength is periodically and randomly changed by rotation of the substrate 60. As used herein, certain embodiments of this invention employ a relative movement between the gain means 2 and a source of optical excitation The movement can be generally linear or rotational, and can be achieved by physically moving one or both of the Gain 1? and the optical excitation. Figure 12b illustrates a further embodiment of a communication system wherein a substrate 61 includes a plurality of region 63 (similar to the pixels illustrated in Figure 9b). A bundle of fiber optic conductors 65 carries the emitted Light from region 63 to coupler 66a, fiber optic 66, coupler 66b, and receiver 68. In this embodiment a laser- (not shown) scans different regions. to 63 in accordance with a predetermined scrutiny algorithm while modulating the information in the scanned beam. The emission from one or more of the pixels is thus transmitted to the receiver 68. As long as the receiver 68 is sensitive to the scrutiny algorithm used by the source of l ser-, there is no control connection between the transmitter- and the receiver-. In other embodiments of the present invention the substrates 60 or 61 may be implemented as part of a optical source that selectively provides one of a plurality of different wavelengths in response to a single wavelength to be used for example in chromatography instrumentation and color printing applications. Figure 13a illustrates an embodiment of this invention wherein the medium 12 is contained within a portion -) |. end 74 of an optical fiber 72, such as within the liner layer to provide a desired wavelength (/?) on a localized region. An l be 76 is used to introduce a first wavelength (Xi) into a second end of the optical fiber 77. An important but not limiting application for this embodiment of the invention is to provide radiation having a predetermined wavelength to a Localized region of tissue. An important aspect of this embodiment of the invention is the radiation pattern that can be achieved, but also within the scope of this invention to include a focus lens, a type of fiber auto-focus, for provide a more directed beam. Figure 13b illustrates a further embodiment wherein a fiber 72b has the gain means including scattered particles distributed within the lining layer of the optical fiber 72. When inserted as a catheter into a structure such as a vein 73, and when pumped through the coupler 72a by the laser 76, the catheter is capable of providing electromagnetic radiation within a predetermined scale of lengths (ie wave along a substantial length of the vein 73. This is useful To provide an optical source directly inside a patient, the radiation can be selected to reduce tissue, cauterize or any number of desired medical procedures.One advantage of this modality is that a single laser source 76 can be used to provide in combination with the terrestrial cat 72b, any of a number of different wavelengths desired.In addition, the catheter outlet is ihernly ornmdirectional and of this type. It can simultaneously irradiate a significant arc of the inner surface or surfaces of the vein 73 or other structure. In this embodiment the radiation is coupled from the core of the fiber 72b within the liner is used to stimulate emission from the gain material 12 that is contained within the liner layer. It is also within the scope of the invention to place a reflector at a terminal end of the catheter in order to reflect the radiation to be returned along the length of the catheter to improve the efficiency of the generation of the catheter. desired wavelength .. Figure 13c illustrates an embodiment of this invention wherein only a portion of the liner layer has in the gain means of this invention that a portion of a surrounding structure is selectively radii. Alternatively, a portion meaning the length of the liner layer may include the gain 12 medium, blunt in Figure 13b, and the surface of the catheter fiber is selectively masked so that the emission to X2 occurs only in one or more predetermined locations. Figure L3c, and also 13d, TB generally indicates a border of jido. Figure 13d illustrates an embodiment of this invention wherein the gain means 12 is contained within the optical coupler 72a. In this case the wavelength? is generated externally to the fabric boundary and is thrown downwardly of the fiber 72b. For this modality a cornun source and a fiber catheter can be used, and the desired wavelengths are provided by placing a particular coupler 72a within the optical path. Figure 13e shows an embodiment of this invention wherein a terminal portion of the fiber 72b is provided with a structure 73 for converting a portion of the pumped wavelength? I into? 2, and also for directing the radiation in a desired address. In this embodiment the structure 73 includes a first portion 73a and a second portion 73b that are disposed at a predetermined angle from each other to the terminal end of the fiber catheter 72b. A surface of the portion 73a includes a layer or cover of the gain material 12, while a surface of the line 73b may be made retlective if desired. Figure L3f illustrates a further embodiment of this invention wherein the terminal portion of the fiber catheter 72b has a region 78 that is frosted or is some other shape to cause the radiation output to the length of 2 2 to be In general, the invention provides a number of valuable medical applications for treating and / or removing tissues selectively, for example the wavelength generated can be used in a manner analogous to the scalpel ar tissue.

It should also be understood that the fiber 72b does not need to be inserted into a structure, but can also be used to irradiate a portion of the surface thereof. For example, and with reference to the embodiment of Figure 13d, the fiber 72 can be placed in a suitable support structure or jacket that allows it to be held in the hand, and a practitioner can then selectively apply the length of wave 2 that is emitted from the terminal end to a localized region of tissue, such as the skin, or to an internal tissue during a surgical procedure. Figure 14 illustrates an embodiment of this invention showing a projection system having a screen 82 that is uniformly or selectively covered with the medium 2. For example, only the regions 86a and 86b are covered with the medium. A conventional projector 84 is used to project light 84a carrying an image, such as a moving image, on the screen 82. The system 80 also includes a laser scanner 88 projecting and rapidly scanning a beam 88a having a first length of wave (Xi) selectively on screen 82, and in particular 'in Regions 86a and 85b. Regions 86a and 06b, when scanned by beam 88a, emit a bright and substantially monochromatic light that is seen by an audience. As a result, localized regions of the screen 82 are illuminated to provide special effects. Can the scrutiny control signal be provided from the projector 84 by recording the same on a track of the film? another image storage means that is used to project the image 84a. For example, curnapna dye 120 in combination with AI2O3 can be placed on a surface as a cover or layer and will be substantially invisible to an observer until it is illuminated by a suitable excitation source. When illuminated, the portion of the screened particle / particle layer emits a bright blue light that is non-saturable. In a further embodiment of the invention, the screen 82 is a billboard having an advertisement message printed thereon, and the laser scanner is mounted to scan the billboard in the selected regions R6a and 86b so as to cause the selected portions of the billboard to be scanned. announced message emits a substantially monochromatic bright light having one or more wavelengths (\ 2 and \ 3) » In general, iffedio 12 can be used for a number of external applications where it is desired to provide an easily visible or detectable mark or region. These applications include, but are not limited to, emergency marker, road barricades, marking predetermined routes for robotic vehicles, and safety clothing for pedestrians. The middle 12 can also be used as a paint component to mark roadways and to paint road signs. For this applications the automobiles, school buses and the like can be equipped with a suitable source for irradiating the markers that are comprised of the medium 12. The markers can also be used on automobiles to increase the operation of the finding systems of the scale of Car-mounted laser used to avoid collision. That is, the marks provide a strong and quickly detectable return from a car when it is illuminated with a suitable laser detector. In addition, the use of different wavelengths for different classes of vehicles allows the discrimination of the target to be carried out quickly. Figure 15a illustrates an embodiment of this invention wherein a plurality of objects 92a-92b each include a covered region 93-93b comprised of the medium 12. A laser-90 emits a first wavelength (Xi) to illuminate the objects 92. A detector 94 is positioned to detect at least one of the wavelengths (? 2 and? 3) emitted by the covered regions. In the illustrated example, the objects 92a are all identical and all emit at the same wavelength \ 2. Fl object 92b emits at wavelength \ 3. This arrangement is useful in, for example, quality control and classification operations where it is desired to provide a homogeneous population of objects by detecting and removing different objects from the population. For example, and for a given operation where it is desired to provide only the objects 92a, the detector 94 may be provided with a filter or other means to pass only the wavelength (3 3). The output of the detector 94 is connected to a control unit 96 that generates an output signal in response to a detection of the wavelength X3. The output signal can be used to generate a visual or audio alarm signal or activate a diverter mechanism to automatically reset the object 92b. Each article can be coded with more than one covered region (for example each one can include these regions) allowing greater selectivity. Figure 15b illustrates an additional embodiment in which a robot manipulator arm 98 has an end effector portion 98a for grasping objects, such as a plurality of bolts comprising the equipment 92. In this embodiment of the invention the laser 90, such as a diode or laser, is provided on or near the end effector portion 98a to irradiate- Objects that are disposed in proximity to the effector extr-erno. Alternatively, the laser 90 may be remotely provided and the output thereof tr-passed through an optical fiber to the end effector portion 98a. The detector 94 is also arranged to detect the radiation emitted from the objects that are illuminated by the laser 90. In the illustrated embodiment the bolts of a first length include a covered region comprised of the means 12 so as to emit the radiation of a first wavelength, while the second length pins include a covered region comprised of the medium 12 so as to emit radiation of a second wavelength. A manipulator controller (not shown) is responsible for the detected radiation to select or prevent an object from emitting a particular wavelength. It can be appreciated that this embodiment of the invention does not require complex image processing software to distinguish the objects from each other. Rather, the objects are inherently distinguishable due to the wavelength that each of them emits. Figure 16 illustrates an embodiment of this invention wherein the means 12 is employed to specifically form a bar code 104 on a surface of an object 102. Fn response to illumination with a long wavelength? I by a If 100, the bar code 104 emits a bright light substantially monochromatically at a wavelength of \ 2. A detector 106 is sensitive to the emitted light and is coupled to a conventional bar code reader (not shown). This embodiment of the invention provides a bar code that has a superior visual contrast. In addition, this embodiment of the invention allows the wavelength to encode Bar-ras code information. This is, all or a part of the bar code information can have a meaning at a first wavelength and a meaning modified or completely different at a second wavelength. In this case the bar code reader preferably includes a wavelength discrimination means, such as a filter and / or a grid, to also identify and detect the emitted wavelength. It is also within the scope of the invention to select a means 12 which is substantially invisible to an observer so as to provide an "invisible" bar code when it is not irradiated Figure 17 illustrates an embodiment of this invention wherein the means 12 is applied as a cover 114 to an object 110 that is capable of internally transmitting a wavelength or wavelengths that are emitted by the cover 114. This mode exploits the response times (Je short and rapid pulsation of the medium 12. In response to the pulsed laser source that emits a wavelength?, the cover 114 emits light with the wavelength X2. The emitted light propagates within the object 110. In response to a discontinuity (change in the refractive index), such as a body 112 that is located within the object 110, a portion of the wavelength 2 is reflected back behind the surface having the cover 114. The reflected portion passing through the cover 114 sows the color-ante molecules contained within the cover 114 thus increasing the exit of the cover 114 to the wavelength X2 when it is simultaneously illuminated with a pulsation of the pulse laser source. A detector 116 is positioned to detect the amplitude of the pulse (J return to the wavelength \ 2.) The return pulse conveys temporal and spatial information concerning the internal structure of the object 110. For example, this mode of the invention can be used in a typing application where it is desired to detect an object within the human body It is also within the scope of the invention to use a plurality of covers 114 in different surface regions, and to employ triangulation techniques for locate * exactly the body 112. As in the embodiment of Figure 10, the cover 1 L4 can be applied to a transparent substrate (not shown) prior to application to the surface of the object 110. Also, the cover 114 can be comprised of of a plurality of different regions emitting each at different wavelengths In this case, the detector 116 is made sensitive to the different lengths of through the use of eg suitable filters and grids. In general, the inter-pulse space (TD) between the pulses (the output), in combination with a delay in the detection of the emitted wavelength (2) gives information about the depth and / or localization of the body 112 from the surface of the object Figure 18 illustrates an embodiment of this invention wherein the means 12 is employed to over-convert a first wavelength (?) to a short wavelength (X2). medium 12 is provided as a thin layer or volume 120 and operates by a resonantly enhanced two-photon absorption process.A suitable colorant for this application is DCM used in combination with dispersion particles as described above. wavelength of 735 n means 12 emits at 630 nm Figure 19 shows an embodiment of the invention wherein means 12 is provided on or within the lens material of a laser eye protector 130. This modality d provides non-saturable eye protection wherein the incident laser radiation is converted to the optical signal at the second wavelength. When the medium 12 is provided with a thin layer a significant portion of the emitted light is directed transversively within the layer. As a result, a significant portion of the input energy is directed out of the eye. Due to the presence of dispersed particles a volume of the medium 12 may appear opaque lucent substance. However, when applied as a thin layer, according to one aspect of this invention, a significant amount of light is able to pass through the layer. This ability to use thin layers or covers of the medium 12 makes use of the medium 12 suitable for a number of applications that could be difficult or impossible to achieve if the smaller dimensions were required to be much larger than the length dispersion . For example, a substrate material can be a tissue that is treated with the medium 12. In response to incident laser radiation from for example a hostile source, a significant portion of the incident reversal power is converted to an emission in one or several wavelengths. This provides the user with a degree of protection from damage due to hostile laser radiation source. Although it was described hitherto primarily in the context of a laser dye in combination with scattered particles that are illuminated and radiated by a laser source -It should be appreciated that in other embodiments of the invention a surgical material can be used in combination with the dye and the dispersion particles. This eliminates the need to use an optical source to pump the dye molecules while the urine material provides sufficient energy. A suitable solvent-based system includes an alkali metal base (e.g., sodium hydroxide), hydrogen peroxide, a non-hydroxyl solvent (e.g., (dibutyl-tinlate), an oxalate ester (e.g. -tpclorofeni lo), and a laser dye to be excited (for example a suitable rhodarnin) in combination with a suitable dispersion phase (nanoparticles, voids, etc.). The electrically stimulated gain means are also within the For example, the PPV material can be used in combination with dispersion particles, thus eliminating the need to provide a colorant.The PPV can be electrically driven or optically driven to provide similar optical emission to the being, or It is also known that the fluorescence of some dyes, generally known as electrochromic dyes, can be modulated. by application of an electric field in the order of 1K V / crn. As such, the use of an electrochromic dye in combination with the dispersion particles allows the emitted wavelength to be modulated on a wavelength scale. Due to the thinness of the film, in accordance with one aspect of the invention, only a relatively modest electrical potential (eg, one volt) is required to generate the electric field potential required. In general, due to the very small dimensions of the regions of the gain medium that are made possible by the teachings of this invention (for example dozens of wavelengths), the volume of the medium that is required to obtain the emission subst ancial monochromatic desired er-ta in the order of the size of the structures of the cell. This allows a microscopic amount of the medium 12 to be used to observe and / or influence the operation of the cell. In view of the above description of a number of embodiments of this invention, it should be understood that Modifications to these modalities can be made, and that these modifications are all within the scope of the teaching of this invention, For example, the use of the invention is not limited only to those specific applications that have been expressly described before, nor is teaching of this invention limited only to the specific materials, concentrations, wavelengths that have been described in detail above For example, the invention can be used in a modality that obtains gain through a non-linear treatment by dispersion Rarnan stimulated or spontaneous This is illustrated in Figures 20a-20c In Figure 20a a Ra an scattering system includes a gain medium first non-linear (a gas such as methane or O 2) contained within a housing 140. Typically, high input powers are required to stimulate emission from a gain medium. In the illustrated embodiment a pumping wavelength (x?) Is provided at a length of mirrors 142 which directs most of the pumping into the housing 140. Part of the pumped radiation is diverted to a cell, cover or body The medium 12 includes a second wavelength (? 2) which acts as a seed to effectively decrease the threshold of the scattering amplifier Ra an enclosed within the housing 140. This is a non-linear mechanism, as opposed to to a linear gain mechanism In the embodiment of Fig. 20b the means 12 is provided on an input front of the housing 140 thus simplifying the embodiment of Fig. 20a.

In the embodiment of FIG. 20c the means 12 is provided on a rear face of the housing 140. In this configuration the medium 12 responds to the wavelength pumped by emitting the radiation seeded back into the housing 140. A mirror said ico external 143 directs the second wavelength to a desired optical path. In this modality, the beam of the Raman scattering amplifier exhibits a broad spectrum of approximately 4 manometers having a very narrow peak (LO-2), as an additional example of the utility of this invention. reference is made to figure 21 which illustrates a small particle or a sphere having a nominal diameter of for example about 30u.The sphere includes the medium 12 in or within a surface region thereof or distributed throughout the entire sphere volume An excitation source provides a first wavelength that is focused downward at approximately the diameter of the sphere.In this mode the sphere absorbs the input wavelength and, because of the fast emission properties of the means 12, almost immediately emits the second wavelength, that is, in which the medium 12 is substantially non-saturable, the sphere is able to repeatedly receive pulses of incoming radiation. It must be shown that a significant force is exerted on this sphere by this treatment, in which the emission from the sphere is isotropic. As such, and if the sphere were suspended in a spray or liquid, the sphere moved away from the incoming pumping beam at a high velocity without significant heating. It can be appreciated that this embodiment of the invention provides a pair-particle accelerator in the order of tens of 5 micro meters in diameter. The resulting particle flow can be used to treat material, such as cutting and surface erosion. The resulting particle stream can also be used to release small amounts of a substance, such as a pharmaceutical product to a specific region.

Lf) inside an object. This modality takes advantage of the capacity of the medium 1. 2 to emit laser light isofropically and very rapidly away from the energy received from the incoming pumping beam. Figure 22 is a cross-sectional view not to scale of a polymer-based light emitting device 150 which benefits from the enlargement and reduction of the emission that is possible by this invention. The aspect of the enlargement and decrease of the emission is seen by comparing the trace a of Figure 1 0 to trace b of Figure i. The device 150 includes a first electrode L52, a region 153 comprised of the gain medium of this invention, and a second electrode 154 substantially transparent. An electrical power source (AC or DC 5) is shown schematically as a battery 156 which is coupled through electrodes 152 and L54.

The region 153 may be comprised of a layer (having a thickness within the range of about 1,000A to 5000 fi) of an organic polymer such as polyphenelin vmelma (PPV) having dispersion particles of suitable dimensions (for example 30fi a 50fi) conforming aggregates (Jad with this invention) The electrode 152 may be comprised of oxidized aluminum having the region 153 of the espm coated thereon.The transparent electrode L54 may be comprised of (mio-tin oxide (TT0) ) "During the operation, the injection of carrier-charge battery 156 causes an emission of the PPV in a known manner In accordance with this invention, the dispersion particles cause an expansion and a decrease in the emission of PPV, As indicated in Figure 1, trace "a." It is also within the scope of this invention to add a suitable colorant to region 153 which absorbs and remits the PPV emission. non-scale cross-sectional view of an electrically operated optical source 160 that is constructed in accordance with an aspect of this invention, wherein the gain means 12 of this invention is applied as a cover 164 to an emitting face of a semiconductor laser iodine 162 to provide an emission at a wavelength (2) that differs from the length of fundamental emission wave (? i) of the iodine of l. A suitable source of electrical energy, shown schematically, as a battery 166 is applied through a laser iodine union 162 of conventional shape. The laser output 162 may be operated in a gain change mode, and may be a type of transverse edit, as illustrated or a vertical emission type. This embodiment of the invention allows one type of laser diode to be constructed so as to provide one of a number of different desired output wavelengths, as a function of the optical properties of the selected gain medium of the cover 164. FIG. 24a is an elevation view not to scale, and FIG. 24b is a non-scale top view showing an embodiment of this invention wherein the gain means 12 of this invention is used as a spectral converter to pump a second medium of gain 172 which is a solution of fluid dye or a roller of l in order to modulate a pump wavelength (i) to the requirements of the second gain means. This pumping source 170 thus employs a layer or cover 174 of the gain medium 12 which is interposed in an optical pump 176, for example a magnesium bulb, and the second gain means 172. The layer or cover 174 provides an emission wavelength (? 2) that is selected as optimal or almost optimal for the second gain medium 17 ?. This embodiment of the invention thus optimizes the optical pump wavelength for the second gain means 172 and allows a single type of pump source 166 to be used with a variety of second gain means. It should be appreciated that in view of the numerous applications and embodiments made possible by this invention, the teaching of this invention is not intended to be limited in scope only to the applications and modalities described below. For example, it is also within the scope of the invention to employ one or more additives to the gain medium to improve performance. For example, a tri-tip extinguisher color, such as COT or hexatpene in combination with the colorant and the dispersion particles, can be used. This allows an almost continuous operation of the medium 12. Also by example, a former dye life tensor such as DA O may be used as an additive. For example, it is also possible to use a sunscreen additive, such as ARQUARD. For a system in which the gain medium is incorporated into an acrylic plastic, such as PMMA, the HEMA solubilizer additive can be used to increase the solubility of the selected dye in the plastic. It should be clear that this invention teaches a gain means which is a multi-phasic system, wherein a first phase is a phase of emission and ampliication of electromagnetic radiation.; a second phase is a phase of dispersion of electromagnetic radiation; and a third phase is a transparent matrix phase.

For example, only, the emission and amplification phase may comprise one or more types of dye molecules and / or semiconductor nanocpstals; the dispersion phase was comprised of oxide particles such as AI2O3, T1O2, S1O2, or Fß2? 3, or metal particles such as Au or Ag; and the matrix phase can comprise a liquid such as methanol, et ilengl 1 col, DMSO, or H2O, or a liquid semi-liquid. , such as a cream, gel, or an epoxy, or a solid such as a polymer selected from for example PMMA, PPV, polyester * or polystyrene. Generally, the dispersion phase is incorporated as a high index of dispersion sites. Retraction contrast such as nanoparticles of an oxide, metal or semiconductor. The dispersion sites may also be incorporated as voids within a porous matrix or substrate, and / or as defects and point discontinuities within the matrix, either alone in combination with the particles. With respect to the use of semiconductor nanocnstals, reference may be made to a publication entitled "Synthesis and Charactenzation of Mearly Monodisperse CDE (E = S, Se, le) Semiconductor Nanocrystal lites ", CB Murray et al., 3. Am. Chern. Soc. 1993, 115, 8706-8715, which teaches a method for producing nanocpstals or semiconductor crystals, from approximately 12 fi to 115 fi in diameter, Which are suitable for use in the practice of this invention In general, a number of direct space semiconductors of the group TI-VT and group IT1-V can be employed, as can indirect space material such as porous silicone. In some embodiments of the invention, the emission and amplification phases and also the dispersion phase may be the same phase, as when using semiconductor particles.A smaller dimension of a body, layer or region comprised of the gain medium may be less that or in the order of the length of the dispersion associated with the dispersion phase.The gain medium can be incorporated into a monolithic one-piece structure such as a leaf, block or sphere or can be to be arranged as one or more layers or regions within or above a subst. Suitable substrates include glasses, dielectrics, polymers, a layer of the gain medium itself, tissue, semiconducting materials, fabrics and metals. A further aspect of this invention is a method of expanding and reducing a band of mission wavelengths of a color-ante, polymer, semiconductor or other emission sources by the steps of a) providing a sample comprised of an optical emitter, such as one or more types of dye molecules or a polymer, in combination with a plurality of dispersion particles or dispersion sites and also a medium that is substantially transparent to the emission wavelength band; b) input energy within the sample with an electric current or with electromagnetic radiation having adequate wavelengths to generate an emission from the optical emitter; c) enlargement and reduction of a band of wavelengths of emission from the optical emitter by dispersion of the emission with the particles or dispersion sites. It should also be apparent that it is within the scope of this invention to employ the electromagnetic radiation that is emitted from the gain medium as a source of heat. In addition, as previously indicated, the teaching of this invention is not intended to be limited in scope by any specific explanation or theoretical reason for the physical, optical, and physical procedures that result in the generation of similar activity to be within of the medium 12. In this way, the teaching of this invention is intended for (in scope) the scope of the following claims.

Claims

NOVELTY OF LR INVENTION CLAIMS 1. - A means of monetary gain comprising: a first phase of said multi-phase gain means constituted by means for the spontaneous emission of electomagnetic radiation in response to an excitation and for the amplification of said electromagnetic radiation emitted by the stimulated emission; and a second phase of said multi-phasic gain means constituted by means for the dispersion of the electromagnetic radiation emitted and amplified to increase the residence time of said electromagnetic radiation within said first phase, characterized in that said means of gain The physical volume has a volume and the amplification of said romagnetic radiation occurs in a portion of said volume of the gain medium.
2. A means of multiphase gain as explained in claim 1, further characterized in that it comprises a third phase of said phase gain means that is substantially transparent at least at the wavelengths of said stimulated emission, said third phase being mixed with the first phase and said second phase within said volume of said gain means.
3. A means of ultimate gain as explained in claim 1, further characterized in that the first phase is comprised of one or more types of dye molecules and wherein the second phase is composed of scattering sites.
4. A means of multi-phase gain as explained in claim 1, further characterized in that the first phase and the second phase are constituted of a semiconductor material.
5. A multi-phase gain means as explained in claim 2, further characterized in that the first phase and the third phase are composed of a polun n co material. 6"- A medium of hypothetical gain as explained in Claim L, further characterized in that the gain means is excited by electromagnetic energy having a prime wavelength for the transmission of electonormal energy by emission. n stimulated, the electromagnetic energy transmitted having wavelengths primarily within a band of wavelengths centered near a second wavelength that is different from the first wavelength. 7. A means of profit as explained in claim 6, further characterized in that the first wavelength is shorter than the second length (Je wave) 8. A medium of phasic gain with explained in claim 6, further characterized in that the first wavelength is longer than the second wavelength 9.- A nultiphasic gain means as explained in claim 1, further characterized in that said first phase is constituted of a polymer, and wherein the second phase is made up of dispersion sites contained within said polymer 10. A multiplying profit medium is explained in claim 1, further characterized because the first phase is constituted of a semiconductor material. that it is provided in the form of particles, and wherein at least a portion of said second phase of the gain medium is constituted by particles of the semiconductor material. * 11.- U The multi-phase gain means as set forth in claim 1, further characterized in that said first phase is constituted of at least one type of dye molecules, and wherein the dye molecules are contained within dent holes. of a matrix material that is substantially transparent to the wavelengths (said stimulated emission and said matrix material containing said dye molecules). 12. A multi-phase gain means as explained in claim 1, further characterized in that said volume of said gain means is arranged adjacent to a surface of a substrate. 13.- A medium of physical profit as explained in claim 12, further characterized in that the volume of the gain means is disposed on said surface as a cover and wherein said surface has a plurality of covers formed thereon. 14. A means of ultiphasic gain as explained in claim 1, further characterized in that the gain means forms a portion of an optical source for the emission of electromagnetic energy and also comprises a source r of energy to stimulate said source. volume of the gain medium for emitting electromagnetic energy primarily within a predetermined band of wavelengths. 15. A multi-phase gain means as explained in claim 14, further characterized in that said predetermined band of wavelengths is centered close to a first wavelength, and wherein the energy source stimulates the volume of the wavelength. said gain means with electronagnetic energy within a band of centered wavelengths close of a second wavelength that differs from the first wavelength. 16. A means of ultiphasic gain as explained in Claim 14, further characterized in that said power source consists of a source of chemical energy. 17. A means of multipurpose gain as explained in claim 14, further characterized because said source of energy is constituted by a power source e Lectr *? Ca. 18. - A means of ultiphasic gain as explained in claim 12, further characterized in that said gain meter forms a portion of an apparatus that includes a source of electromagnetic radiation, said apparatus further comprising: a source of energy to stimulate the volume of the medium of gain for emitting electromagnetic energy primarily within a band of wavelengths that includes a predetermined wavelength, wherein said energy source transmits a beam of electromagnetic energy having a wavelength that differs from said predetermined wavelength; and means for causing relative movement between said beam and said substrate. 19. A means of multi-phase gain as explained in claim 18, further characterized in that the means for causing a relative movement include means for the translation of said substrate. 20. A medium of three-phase gain as explained in claim 18, further characterized in that said means for causing a relative movement include means for scanning said beam. 21. A multi-phase gain means as explained in Claim L, further characterized that said gain value is arranged on a surface of a substrate as a plurality of covers, wherein said individual covers, when excited. , emit energy b3 electromagnetic that is primarily within a narrow band of wavelengths centered near a predetermined length, and wherein the predetermined wavelengths of at least two of said covers are different in each case. 72.- A multi phasic gain means as explained in claim 12, further characterized in that there is a plurality of such substrates each having at least one region of said gain means disposed adjacent to a surface thereof, each being of said substantially transparent substrates at least at the wavelengths of said stimulated emission, and wherein the individual substrates are arranged one over the other in a multi-layered arrangement. 23.- A means of gain m This method is explained in claim 1, further characterized in that said gain means is arranged adjacent to a surface of a substrate within at least one region of said surface, this region being constituted of a plurality of subregions, wherein said gain medium, within the individual sbregions of said plurality, emits electonagnetic energy, when excited, which is primarily within of a band of wavelengths centered near a predetermined wavelength and wherein the predetermined wavelengths of said gain medium, within (At least two such subregions, are different from each other. 24. - A multiphase gain means as explained in claim 1, further characterized in that said volume of gain means is contained within a three-dimensional monolithic structure. 25. A means of nultifasic gain as explained in claim 24, further characterized in that said structure is substantially spherical in shape. 26. A multi-phase gain medium as explained in claim 2, further characterized in that said third phase consists of a material selected from a group consisting of a liquid, a semiliquid, a gel, a cream, a sernisolide, a solid and combinations thereof. 27. A means of optical gain comprising a medium that is substantially transparent at least at a selected wavelength; a plurality of dye molecules contained within said means for the emission and amplification of electromagnetic radiation at at least said selected wavelength, in response to the excitation; and a plurality of particles contained within said medium, said particles having a refractive index that differs from a refractive index of said medium for the dispersion of the electromagnetic radiation that is emitted from said pLity of dye molecules to increase the residence time of the electromagnetic radiation within said medium. 78.- A means of gain co or was explained in claim 27, further characterized in that said plurality of particles have an associated photon scattering length.; and wherein at least one dimension of a volume of said gain means is not significantly greater than the length of the photon scattering. 29. An optical gain means comprising: a medium that is substantially transparent at least at a selected wavelength; and a plurality of particles contained within said medium, said particles being selected from a material emitting electromagnetic radiation by stimulated emission at least at a selected wavelength, in response to excitation, said particles having a refractive index that It differs from a refractive index of said medium for the dispersion of the electromagnetic radiation emitted to increase the residence time of the electromagnetic radiation within said medium, whereby optical gain occurs at least at said length (Je selected wave. 30. A gain means as explained in claim 29, further characterized in that said plurality of particles have an associated photon scattering length, and wherein at least one dimension of a volume of said gain means is not significantly greater. that the scattering length of the photon 31.- A gain medium that exhibits simulated activity ilar to the laser when excited with an excitation source comprising, a medium that is substantially transparent at least at a selected wavelength, said medium having a volume and being constituted by a material selected for emission and amplification of electromagnetic radiation in response to an excitement; and a plurality of particles contained within said medium, said particles having a refractive index that differs from a refractive index of said medium for the dispersion of the electromagnetic radiation emitted to increase * the residence time of the electromagnetic radiation within said means, wherein amplification of said electromagnetic radiation occurs within a portion of the volume of said medium. 32. A gain means as explained in claim 31, further characterized in that said plurality of particles has a scattering length of phot n associated; and wherein at least one dimension of a volume of said gain means is not significantly greater than the length of the scatter of the photon. 33.- An apparatus for the exposure of an image, comprising, an exposure screen having a surface, the surface having a plurality of pixels, each of said pixels being constituted of a substantially non-saturable optical gain means that is sensitive at an excitation above a threshold energy for the emission of electromagnetic radiation within a predetermined narrow band of wavelengths; and a fountain b 7 coupled to said pixels to provide the excitation. 34. An apparatus as set forth in claim 33, further characterized in that said substantially non-saturable optical gain means is constituted of a multi-phase gain means wherein a first phase of said multi-phasic gain means is constituted means for the spontaneous emission of electromagnetic radiation in response to an excitation and for the amplification of said electromagnetic radiation emitted by stimulated emission; and a second phase of said multi-phase gain means is constituted by means for dispersing the electromagnetic radiation emitted and amplified to increase the residence time of the electromagnetic radiation within the first phase. 35. An apparatus as explained in claim 33, further characterized in that said source coupled to said μLelity of pixels is constituted by a power source e1ec t r-oinagne ic., 36.- An apparatus as explained in claim 33, further characterized in that said source copied to said plurality of pixels is constituted by means for injecting charge carriers into each of said pixels. 37., - An apparatus for irradiating a region with electromagnetic radiation having wavelengths within a predetermined band of wavelengths, said apparatus comprising an elongated structure having an input port for coupling to a source of electromagnetic radiation transmitting at least a first wavelength, said elongated structure being comprised along at least a portion of a length thereof of a multi-optical optical gain means constituted of a material having a first phase for the spontaneous emission of electromagnetic radiation within the band of wavelengths in response to electromagnetic radiation having said first wavelength, said first phase then amplifying the electromagnetic radiation emitted by stimulated emission; said material further being constituted of a second phase for the dispersion of the electromagnetic radiation emitted and amplified to increase the residence time of the electromagnetic radiation in said first phase. 38.- An apparition as explained in the claim 37, further characterized in that said elongated structure os fl xibl. 39. An apparatus co or explained in claim 37, further characterized in that said first wavelength is a wavelength outside the predetermined band of wavelengths. 40.- An apparatus as explained in claim 317, further characterized in that said entrance door is coupled to a first end of said elongated structure, and further comprising means coupled to a second extension of said elongated structure to direct at least said electromagnetic radiation emitted and amplified in at least one predetermined direction. 41.- A method to identify an object, including the p > Asses of, provide at least one surface of individual objects within a predetermined class of objects with a means of initial gain where a first phase of the means of mathematical gain is constituted / _. of means for the spontaneous emission of electromagnetic radiation in response to an excitation and for the amplification of said electromagnetic radiation emitted by stimulated emission, and wherein a second phase of the classical phase gain means is constituted of means for dispersion of electromagnetic radiation emitted and amplified to increase the residence time of said electromagnetic radiation within said first phase, the multi-phase gain means being sensitive to electromagnetic radiation having a first wavelength for the emission of electromagnetic radiation with wavelengths within a predetermined band of wavelengths; irradiate objects with the first wavelength; detecting an emission from the irradiated objects, the emission including one or more second wavelengths that are within the predetermined band of wavelengths; and identifying an object as belonging to a predetermined class of objects in accordance with the detected emission including said one or more second wavelengths. OR 42. - A method as explained in the reiviication 41, further characterized in that there is a group of objects comprising one or more predetermined classes of objects and further comprising a step of separating an identified object from the group of objects. 43.- A method for the protection of an object from damage caused by energy contained within incident electromagnetic radiation having wavelengths within a first band of wavelengths, comprising the steps of providing the object with medium of optical gain constituted of a material having a first phase for the spontaneous emission of electromagnetic radiation within a second band of wavelengths in response to excitation with electromagnetic radiation having wavelengths within the first band of wavelengths , the first phase further amplifying the radioactive radiation omitted by * stimulated emission; the material further being constituted of a second phase comprising means for the dispersion of I? electromagnetic radiation emitted and amplified to increase the residence time of electromagnetic radiation within the first phase; and in response to an irradiation of the object with electromagnetic radiation within the first band of wavelengths, using the optical gain means, converting a portion of the energy of the electromagnetic radiation within the first wavelength band to a emission of electromagnetic radiation inside The second band of wavelengths. 44.- An optical system comprising,? N housing containing a medium optical gain ppmer; an optical source for pumping the first optical gain means with a first electromagnetic radiation having a first wavelength; means for converting a portion of the first electromagnetic radiation to a second wavelength for seeding the first gain medium at the second wavelength; wherein said conversion means includes a second optical gain means constituted of a material having a first phase for the spontaneous emission of electromagnetic radiation having the second wavelength, in response to excitation with electromagnetic radiation having the first wavelength, the first phase also amplifying the electromagnetic radiation emitted by * stimulated emission; the material further being constituted of a second phase containing means for the dispersion of electromagnetic radiation emitted and amplified to increase the residence time of the electromagnetic radiation within the first phase. 45. An optical system as explained in claim 44, further characterized in that the second optical gain means is arranged externally to said housing. 46. An optical system as explained in claim 44, further characterized in that said second optical gain means is arranged adjacent to a surface of said housing. 47. An optical system as explained in claim 44, further characterized in that said first optical gain means operates by a non-linear method wherein the optical gain is a non-linear function of an intensity of the electromagnetic radiation having at least one the first wavelength. 48.- A method for the acceleration of an object, comprising the steps of, providing the object with a means of ultiphasic gain where a first phase is constituted of means for the spontaneous emission of electromagnetic radiation in response to an excitation and to amplify - said electromagnetic radiation emitted by stimulated emission; and wherein a second phase of the multi-phase gain means is constituted by means for the dispersion of electromagnetic radiation emitted and amplified to increase the residence time that said electromagnetic radiation within said first phase, the multi-rate gain means being sensitive to the radiation electromagnetic that has a first wavelength for the emission of electromagnetic radiation with wavelengths within a narrow band of wavelengths having a second wavelength that differs from the first wavelength; and in response to an illumination of the object with electromagnetic radiation having the first wavelength, using the gain means, converting a significant portion of the electromagnetic radiation energy at the first wavelength to an isotropic emission of electromagnetic radiation at a second wavelength, where the conversion occurs within a period of time that results in an acceleration force that is applied to the object due to an absorption of photons from the electromagnetic radiation. 49. A method as explained in claim 48, further characterized in that the object is constituted of a selected material and transports the selected material in response to the acceleration force. 50. A laser diode comprising, an active region having an output front to transmit an optical emission within a first wavelength scale; and a cover disposed on said exit face to convert at least a portion of said optical emission to an optical emission within a second wavelength scale, said cover being constituted of a material having a first phase for spontaneous emission of electromagnetic radiation having wavelengths within the second scale of wavelengths in response to excitation with electromagnetic radiation having wavelengths with the first wavelength scale, the first phase also amplifying the electromagnetic radiation emitted stimulated the material further being constituted of a second phase comprising means for the dispersion of the electromagnetic radiation emitted and amplified to increase the residence time of the electromagnetic radiation within the first phase. 51. A laser diode as explained in claim 50, further characterized in that a second phase is constituted by a plurality of particles that are dispersed within said cover and that have an associated cross-section of dispersion; and wherein at least one dimension of said cover is comparable in size to a dimension of said dispersion cross section. 52.- A method for the amplification and deviation of a band of wavelengths of emission from an optical emitter, comprising the steps of, providing an optical emitter in combination with a plurality of dispersion centres that are mixed within a medium which is substantially transparent to the band of emission of wavelengths; introduction of energy within the system to generate a spontaneous emission from the optical emitter; and amplifying and shifting a band of emission wavelengths from the optical emitter by scattering the emission to the dispersion centres. 53.- A method for detecting the presence of a structure within an object, comprising the steps of, providing a surface region of the object with a means of ultimate gain where a first phase is constituted of means for the emission spontaneous electromagnetic radiation in response to an excitation and for the amplification of said electomagnetic radiation emitted by stimulated emission; and wherein a second phase of the multi phasic gain means is constituted by means for the dispersion of the electromagnetic radiation emitted and amplified to increase the residence time of the electromagnetic radiation within the first phase, the multi-phasic gain means being sensitive to electromagnetic radiation having a first wavelength for the emission of electromagnetic radiation with wavelengths within a band of wavelengths having a second wavelength that differs from the first wavelength; irradiating the gain medium with a first pulse of radiation having the first wavelength; propagation of the emitted radiation that has the second wavelength inside the object; in response to the propagation of radiation by finding a change in a refractive index that is associated with the structure, reflecting a portion of the radiation back to the surface of the object; in response to the reflected radiation entering the multi-phase gain medium coincidentally with a second pulse, increasing the emission of the electromagnetic radiation with wavelengths within the wavelength band having the second wavelength; detecting the increased emission; and correlating the detected increased emission with a time between the occurrence of the first and second pulsations to determine at least one distance from the structure to the surface of the object. RESUSCITATION OF THE INVENTION A gain means is constituted of a multi-phase system where: a first phase is a phase of emission 5 of electromagnetic radiation; a second phase is a phase (ie dispersion of electromagnetic radiation) and a third phase is a transparent matrix phase, for example, the emission phase may consist of dye molecules, the dispersion phase may consist of high contrast particles and the The matrix phase may consist of a solvent such as rnet nol; in some embodiments of this invention, the emission and dispersion phases may be the same phase, as when semiconductor particles are used; a smaller dimension of a body comprised of the means of gain may be less than L5 a dispersion length associated with the dispersion phase; it is shown that almost no threshold laser vision is observed in optically pumped tmte-rnef nol solutions The strong dispersion containing colloidal T1O2 or ruby nanoparticles of AI2O3; the emission from the high gain colloid 20 exhibits a slope change in the linear input-output characteristics above a critical pumping pulse energy; the change in slope is accompanied by a reduction in the spectral line with an attic bicro spectrum that appears at high pumping energies. ? 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