초록 ▼

The present invention relates to a numerous user laser communications optical system. Numerous optical signals comprising a number of channels are simultaneously received and demultiplexed (and/or multiplexed and transmitted) at a numerous access communication device. The numerous access communicati

The present invention relates to a numerous user laser communications optical system. Numerous optical signals comprising a number of channels are simultaneously received and demultiplexed (and/or multiplexed and transmitted) at a numerous access communication device. The numerous access communication device may comprise multiple stages that each include a multiple order waveplate and a polarizing beam splitter. The multiple order waveplate is configured so that it retards a first electrical field component of signals corresponding to certain channels in a frequency grid in an integer multiple of wavelengths with respect to a second electrical field component, and retards a first electrical field component of signals corresponding to other channels in the frequency grid in an integer multiple of wavelengths plus one-half a wavelength with respect to a second electrical field component. Separation can then be performed on the basis of the resulting opposite polarization.

대표청구항 ▼

What is claimed is: 1. A method for demultiplexing optical signals, comprising: simultaneously receiving at a telescope having a first aperture a plurality of optical signals transmitted from at least a first remote source, said optical signals spaced from one another substantially regularly in fre

What is claimed is: 1. A method for demultiplexing optical signals, comprising: simultaneously receiving at a telescope having a first aperture a plurality of optical signals transmitted from at least a first remote source, said optical signals spaced from one another substantially regularly in frequency and having the same polarization, said optical signals including a primary set of even signals including at least one even signal and a primary set of odd signals including at least one odd signal, wherein said plurality of optical signals comprise a plurality of communication channels; retarding a first electrical field component of said at least one primary even signal with respect to a second electrical field component of said at least one primary even signal by about an integer multiple of wavelengths of said at least one primary even signal, wherein said at least one primary even signal has a first polarization after said retarding; retarding a first electrical field component of said at least one primary odd signal with respect to a second electrical field component of said at least one primary odd signal by an integer multiple of wavelengths plus about one-half a wavelength, wherein said at least one primary even signal and said at least one primary odd signal are approximately oppositely polarized from one another, wherein said at least one primary odd signal has a second polarization after said retarding; directing said at least one primary even signal having said first polarization along a first path; and directing said at least one primary odd signal having said second polarization along a second path. 2. The method of claim 1, further comprising: linearizing a polarization of said plurality of received optical signals before retarding. 3. The method of claim 1, further comprising: receiving said at least one even signal directed along said first path at a first receiver; and receiving said at least one odd signal directed along said second path at a second receiver. 4. The method of claim 1, wherein said retarding a first electrical field component of said at least one even signal with respect to a second electrical field component of said at least one even signal by about an integer number of wavelengths and said retarding a first electrical field component of at least one odd signal with respect to a second electrical field component of said at least one odd signal by about an integer number of wavelengths plus about one-half a wavelength comprises passing said plurality of optical signals through a first waveplate, wherein said first waveplate has indices of refraction along transmission axes of said first waveplate and a thickness such that said first electrical field component of said at least one primary even signal is retarded with respect to said second electrical field component of said at least one primary even signal by said first waveplate by about an integer multiple of wavelengths and such that said first electrical field component of said at least one primary odd signal is retarded with respect to said second electrical field component of said at least one primary odd signal by said first waveplate by an integer multiple of wavelengths plus about one-half a wavelength. 5. The method of claim 1, wherein said plurality of optical signals includes a plurality of at least one of said at least one even signal and said at least one odd signal, the method further comprising: separating said plurality of at least one of said at least one even signal and said at least one odd signal using at least one of a bandpass and a bandstop filter in combination with a second polarizing beam splitter. 6. The method of claim 1, wherein said plurality of optical signals includes a plurality of at least one of said at least one even signal and said at least one odd signal, the method further comprising: separating said plurality of at least one of said at least one even signal and said at least one odd signal using a tilted dichroic filter. 7. The method of claim 1, wherein said plurality of optical signals are received from a telescope having a single aperture. 8. The method of claim 1, further comprising: directing one primary even signal to a first receiver; and directing one primary odd signal to a second receiver. 9. A method for demultiplexing optical signals, comprising: receiving at a telescope having a first aperture a plurality of optical signals, said optical signals spaced from one another substantially regularly in frequency and having the same polarization, said optical signals including a primary set of even signals including at least one even signal and a primary set of odd signals including at least one odd signal, wherein at least first and second even signals are included in said primary set of even signals, and wherein at least first and second odd signals are included in said primary set of odd signals; retarding a first electrical field component of said at least one primary even signal with respect to a second electrical field component of said at least one primary even signal by about an integer multiple of wavelengths of said at least one primary even signal, wherein said at least one primary even signal has a first polarization after said retarding; retarding a first electrical field component of said at least one primary odd signal with respect to a second electrical field component of said at least one primary odd signal by an integer multiple of wavelengths plus about one-half a wavelength, wherein said at least one primary even signal and said at least one primary odd signal are approximately oppositely polarized from one another, wherein said at least one primary odd signal has a second polarization after said retarding; directing said at least one primary even signal having said first polarization along a first path, wherein said directing said at least one primary even signal having said first polarization along a first path comprises directing said first and second even signals along said first path, wherein said first even signal comprises a first secondary even signal and said second even signal comprises a first secondary odd signal; directing said at least one primary odd signal having said second polarization along second path, wherein said directing said at least one primary odd signal having said second polarization along said second path comprises directing said first and second odd signals along said second path, wherein said first odd signal comprises a second secondary odd signal and said second odd signal comprises a second secondary even signal; retarding a first electrical field component of said first secondary even signal with respect to a second electrical field component of said first secondary even signal by about an integer multiple of wavelengths of said first secondary even signal, wherein said first secondary even signal has said first polarization after said retarding; retarding a first electrical field component of said first secondary odd signal with respect to a second electrical field component of said first secondary odd signal by an integer multiple of wavelengths plus about one-half a wavelength, wherein said first secondary odd signal has a second polarization after said retarding, wherein said first secondary even signal and said first secondary odd signal are approximately oppositely polarized from one another; directing said first secondary even signal having said first polarization along a third path; directing said first secondary odd signal having said second polarization along a fourth path; retarding a first electrical field component of said second secondary even signal with respect to a second electrical field component of said second secondary even signal by about an integer multiple of wavelengths of said second secondary even signal, wherein said second secondary even signal has said first polarization after said retarding; retarding a first electrical field component of said second secondary odd signal with respect to a second electrical field component of said second secondary odd signal by an integer multiple of wavelengths plus about one-half a wavelength, wherein said second secondary odd signal has a second polarization after said retarding, wherein said second secondary even signal and said second secondary odd signal are approximately oppositely polarized from one another; directing said second secondary even signal having said first polarization along a fifth path; and directing said second secondary odd signal having said second polarization along a sixth path. 10. The method of claim 9, wherein said retarding a first electrical field component of said first secondary even signal with respect to a second electrical field component of said first secondary even signal by about an integer multiple of wavelengths of said first secondary even signal and said retarding a first electrical field component of said first secondary odd signal with respect to a second electrical field component of said first secondary odd signal by an integer multiple of wavelengths plus about one-half a wavelength comprises passing said first secondary even signal and said first secondary odd signal through a second waveplate, wherein said second waveplate has indices of refraction along transmission axes of said second waveplate and a thickness such that said first electrical field component of said first secondary even signal is retarded with respect to said second electrical field component of said first secondary even signal by said second waveplate by about an integer multiple of wavelengths, and wherein said first electrical field component of said first secondary odd signal is retarded with respect to said second electrical field component of said first secondary odd signal by said second waveplate by an integer multiple of wavelengths plus about one-half a wavelength. 11. A communication device, comprising: a telescope having a first aperture; a first differentiating waveplate having a first area, wherein said first differentiating waveplate receives optical signals collected by said telescope, wherein said first differentiating waveplate has fixed indices of refraction and a thickness selected such that a first optical signal having a first wavelength and having a first polarization when received anywhere within said area of said first differentiating waveplate exits said first differentiating waveplate having said first polarization, wherein a second optical signal having a second wavelength and having said first polarization when received anywhere within said area of said first differentiating waveplate exits said first differentiating waveplate having a second polarization, wherein said first differentiating waveplate retards at least one component of said first signal by an integer number of wavelengths, and wherein said first differentiating waveplate retards at least one component of said second signal by an integer number of wavelengths plus or minus about one-half a wavelength; and a first polarizing beam splitter, wherein said first polarizing beam splitter receives said first and second optical signals from said first differentiating waveplate, wherein said first polarizing beam splitter directs said first optical signal having said first polarization along a first path, and wherein said first polarizing beam splitter directs said second optical signal having said second polarization along a second path. 12. The system of claim 11, wherein said first differentiating waveplate has a first index of refraction in a first direction and a second index of refraction in a second direction, and wherein said first index of refraction is different than said second index of refraction. 13. The system of claim 11, wherein said first differentiating waveplate has a thickness and indices of refraction such that it retards an electrical component of said first optical signal by no less than 50 waves with respect to a second electrical component of said first optical signal. 14. The system of claim 11, further comprising a linearizing waveplate in an optical path between said telescope and said first differentiating waveplate, wherein said linearizing waveplate transforms signals received by said telescope as circularly polarized optical signals to signals having said first polarization, wherein said first polarization is a linear polarization. 15. The system of claim 14, wherein said first differentiating waveplate is a birefringent waveplate with crystal axes that are aligned at an angle of about 45 degrees to a plane of said first polarization. 16. The system of claim 11, further comprising: a receiving fiber, wherein said receiving fiber receives an optical signal from one of said first polarizing beam splitter and a second polarizing beam splitter. 17. The system of claim 11, wherein said first differentiating waveplate comprises a multiple order waveplate. 18. A communication device, comprising: a telescope having a first aperture; a first differentiating waveplate, wherein said first differentiating waveplate receives optical signals collected by said telescope, wherein said first differentiating waveplate has indices of refraction and a thickness selected such that a first optical signal having a first wavelength and having a first polarization when received at said first differentiating waveplate exits said first differentiating waveplate having said first polarization, wherein a second signal having a second wavelength and having said first polarization when received at said first differentiating waveplate exits said first differentiating waveplate having a second polarization, and wherein a third optical signal having a third wavelength and having said first polarization when received at said first differentiating waveplate exits said first differentiating waveplate having said first polarization; a first polarizing beam splitter, wherein said first polarizing beam splitter receives said first, second, and third optical signals from said first differentiating waveplate, wherein said first polarizing beam splitter directs said first optical signal having said first polarization along a first path, wherein said first polarizing beam splitter directs said second optical signal having said second polarization along a second path, and wherein said first polarizing beam splitter directs said third optical signal having said first polarization along said first path; a second differentiating waveplate, wherein said second differentiating waveplate receives said first and third optical signals directed along said first path by said first polarizing beam splitter, wherein said second differentiating waveplate has indices of refraction and a thickness selected such that said first optical signal having a first optical wavelength and said first polarization when received at said second differentiating waveplate exits said second differentiating waveplate having said first polarization, and wherein said third signal having a third wavelength and having said first polarization when received at said second differentiating waveplate exits said second differentiating waveplate having said second polarization; and a second polarizing beam splitter, wherein said second polarizing beam splitter receives said first optical signal and said third optical signal from said second differentiating waveplate, and wherein said second polarizing beam splitter directs said first optical signal having said first polarization along a third path, and wherein said second polarizing beam splitter directs said third optical signal having said second polarization along a fourth path. 19. The system of claim 18, further comprising: a fast steering mirror interposed between at least one of said first polarizing beam splitter and a second polarizing beam splitter, wherein said fast steering mirror directs at least one optical signal towards said receiving fiber. 20. A communication device, comprising: a telescope having a first aperture; a first differentiating waveplate, wherein said first differentiating waveplate receives optical signals collected by said telescope, wherein said first differentiating waveplate has indices of refraction and a thickness selected such that a first optical signal having a first wavelength and having a first polarization when received at said first differentiating waveplate exits said first differentiating waveplate having said first polarization, and wherein a second signal having a second wavelength and having said first polarization when received at said first differentiating waveplate exits said first differentiating waveplate having a second polarization; a first polarizing beam splitter, wherein said first polarizing beam splitter receives said first and second optical signals from said first differentiating waveplate, wherein said first polarizing beam splitter directs said first optical signal having said first polarization along a first path, and wherein said first polarizing beam splitter directs said second optical signal having said second polarization along a second path; a first transmitting fiber, wherein said first transmitting fiber generates a third optical signal having a third wavelength and said first polarization that is received by said first polarizing beam splitter, wherein said third optical signal is directed to said first waveplate, and wherein said third optical signal leaves said first waveplate and enters said telescope having a circular polarization; and a second transmitting fiber, wherein said first transmitting fiber generates a fourth optical signal having a fourth wavelength and said second polarization that is received by said first polarizing beam splitter, wherein said fourth optical signal is directed to said first waveplate, and wherein said fourth optical signal leaves said first waveplate and enters said telescope having said circular polarization. 21. A communication system, comprising: means for gathering light, wherein said light comprises a plurality of optical signals received at said means for gathering light simultaneously, and wherein said plurality of optical signals comprise a plurality of communication channels; means for multiplexing/demultiplexing at least some of said plurality of optical signals, wherein said means for multiplexing/demultiplexing at least some of said plurality of optical signals further comprise means for retarding at least one component of said signals by an integer number of wavelengths and means for retarding at least one component of said signals by an integer number of wavelengths plus or minus about one-half a wavelength; and means for receiving/transmitting said at least some of said optical signals, wherein said at least some of said optical signals passed between said means for multiplexing/demultiplexing are at least one of received and generated. 22. The system of claim 21, wherein said means for multiplexing/demultiplexing comprise a first means for differentially polarizing, wherein adjacent ones of said optical signals alternate between even and odd channels, wherein even optical signals passed to said means for multiplexing/demultiplexing by said means for gathering light pass through said means for differentially polarizing without having their polarization altered, and wherein odd optical signals passed to said means for multiplexing/demultiplexing by said means for gathering light pass through said means for differentially polarizing with their polarization changed to a polarization that is about opposite the polarization of said even optical signals.