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Title: Quantum amplifier having passive core and active cladding providing signal gain by interaction of evanescent-wave components of signal and pump beams propagating along the core
Claims: We claim: 1. Apparatus for amplifying signal light energy of a first given band of wavelengths, comprising a. an elongated dielectric waveguide structure having an entry face and an opposed exit face; b. a source of coherent laser light pumping energy of a second band of different wavelengths; and c. means including a dichroic mirror for directing said signal light energy and a beam of said coherent laser light pumping energy simultaneously into said entry face, said means for directing said signal light energy further including 1. a mode-converting volume hologram (110) having a spatial interference pattern recorded throughout the volume of the holographic medium such that signal light energy having a first predetermined wave front distribution incident thereon is transmitted through said hologram and converted to a desired mode order number by internal reflection from said interference pattern into a second predetermined wave front distribution, and 2. a first optical lens (15) for focusing the light transmitted by said volume hologram into the entry face of said waveguide structure to launch said signal light energy for propagation along said waveguide structure as a predetermined higher order number mode of said waveguide; d. said waveguide structure including 1. a passive dielectric core having low absorption to said given bands of wavelengths, said core having a smooth continuous side wall portion throughout the length thereof, and 2. a cladding of a laser material intimately adhered on said side wall portion, a. said cladding having an index of refraction lower than the index of refraction of said core and confining the signal and pumping energies propagating along said core as bound modes of the structure, b. said cladding including an active medium capable of being optically pumped by ion coupling with evanescent-wave components of said laser light pumping energy and capable of interacting with evanescent-wave components of signal light propagating along said core and being stimulated to fluoresce in said first given band of wavelengths, whereby to amplify said signal light. 2. Apparatus as defined in claim 1, and further including e. an output optical transmission line (101); f. second hologram means (25) arranged between the waveguide structure exit face and said output line, said second hologram means comprising a volume hologram having an interference pattern such that when amplified signal light energy issuing from said exit face having a third predetermined wavefront distribution is incident on said second hologram means, said amplified light enrgy is transmitted through said second hologram means and is converted to a predetermined lower order number mode by internal reflection from said interference pattern into a fourth predetermined wave front distribution; and g. second optical lens means (26) for focusing the amplified light energy upon said output line for propagation therealong as said predetermined lower order number mode. 3. Apparatus for amplifying signal light energy as defined in claim 2, wherein said pumping light energy is of longer wavelength than said signal light energy and is directed into said entry face. 4. Apparatus for amplifying signal light energy as defined in claim 3, wherein said signal light energy is the radiation output lobe of a fiber optic waveguide transmission line, and further wherein said output transmission line is also a fiber optic waveguide. Other info: Inventors: Hill, Kenneth O. (Kanata, CA, US) Watanabe, Akira (Kanata, CA, US) Chambers, John G. (Kanata, CA, US) Application Number: 350687 Filing Date: 1973-04-13 Publication_date: 1976-04-13 Assignee: Canadian Patents and Development Limited (Ottawa, CA) Primary Class(es): 359/1 359/341.31, 359/342, 359/345, 372/9 Other Classes: US Patent Ref:
Other Refs: Other References: Ippen et al., "An Evanescent Field Pumped Dye Laser", 2/10/72, PPTLA4- 1 to 4, Opt. Soc. of Amer., Integrated Optics Meeting Technical Papers. Watanabe et al., "Amplification of Light . . . Pumping", 4/1/73, pp. 761-771, Canadian Journal of Physics, Vol. 51, No. 7. Hill et al., "Amplification of . . . Interactions", 10/7/71, p. 1579, Jour. Opt. Soc. of Amer., Vol. 61, No. 11. Ippen et al., "Evanescent-Field Pumped Dye Laser", 10/1/72, pp. 301-302, A.P.L., Vol. 21, No. 7. Koester, "Laser Action by . . . Reflection", 9/66, pp. 580-584, IEEE, J.Q.R., Vol. QR-2, No. 9. | |