USPL-FSO lasercom point-to-point and point-to-multipoint optical wireless communication

Abstract

Enhancements in optical beam propagation performance can be realized through the utilization of ultra-short pulse laser (USPL) sources for laser transmit platforms, which are can be used throughout the telecommunication network infrastructure fabric. One or more of the described and illustrated features of USPL free space-optical (USPL-FSO) laser communications can be used in improving optical propagation through the atmosphere, for example by mitigating optical attenuation and scintillation effects, thereby enhancing effective system availability as well as link budget considerations, as evidenced through experimental studies and theoretical calculations between USPL and fog related atmospheric events.

What is claimed is: 
     
       1. An optical communication transceiver system comprising:
 an ultra-short-pulse-laser (USPL) source operating in the wavelength range of 1.3 to 1.6 microns, the USPL source configured to generate a beam having a mode-locked pulse repetition rate comprising light pulses each having a duration of approximately one (1) nanosecond or shorter; 
 an electronic switching element external to the said USPL source configured to provide an electronic clock signal suitable to control the mode-locked pulse repetition rate of the USPL source; 
 an optical modulation element external to the said USPL source driven by an electronic data signal from the said external electronic switching element that is synchronized with the said clock signal and configured to apply a non-return to zero modulation signal to the said optical modulation element resulting in first data impressed on the said light pulses in a return to zero first modulated optical signal configured for transmission to a second optical communication transceiver system located remote from the optical communication transceiver system; and 
 an optical receiver configured to receive a second modulated optical signal comprising second data from the second optical communication transceiver system. 
 
     
     
       2. An optical communication transceiver system as in  claim 1 , wherein the said electronic switching element operates in accordance with Ethernet protocols including an output electronic data signal in a non-return to zero form. 
     
     
       3. An optical communication transceiver system as in  claim 1  with a pulse multiplier module external to the said USPL source and located in the output optical beam path before the said external modulator element and configured to receive the beam and increase the pulse repetition rate of the beam. 
     
     
       4. An optical communication transceiver system as in  claim 3  such that the pulse multiplier module comprises a laser beam splitter and a laser beam recombiner and at least one of the following located between the laser beam splitter and laser beam recombiner: (1) a series of fixed length fiber optic delay lines having varying lengths, (2) a series of fiber optic coils each wrapped around the circumference of a cylindrical piezoelectric element that expands or contracts in circumference when electrically actuated, or (3) a series of piezoelectric elements that axially expand or contract a microfiber collimator when electrically actuated. 
     
     
       5. An optical communication transceiver system as in  claim 4 , wherein the pulse multiplier module has been configured to increase the laser beam pulse repetition rate of the laser beam exiting the multiplier module to exceed one (1) Gbit/sec. 
     
     
       6. An optical communication transceiver system as in  claim 3 , wherein the pulse multiplier module is integrated into a single photonic chip. 
     
     
       7. An optical communication transceiver system as in  claim 1 , wherein the said USPL source has been configured to generate a beam comprising light pulses with the duration of each pulse less than approximately a picosecond. 
     
     
       8. An optical communication transceiver system as in  claim 1 , wherein the modulating element has been configured to operate in a digital on-off keying (OOK) mode to either pass each individual optical pulse, corresponding to a digital “1”, or block each individual optical pulse, corresponding to a digital “0”, and thereby create a digital optical communication data stream consisting of sequential “1”s and “0”s. 
     
     
       9. An optical communication transceiver system as in  claim 1 , wherein the modulating element has been configured to operate in a digital on-off keying (OOK) mode to either pass a group consisting of more than one successive optical pulses, corresponding to a digital “1”, or block a group consisting of more than one successive optical pulses, corresponding to a digital “0”, and thereby create a digital optical communication data stream consisting of sequential “1”s and “0”s. 
     
     
       10. An optical communication transceiver system as in  claim 1 , further comprising an optical multiplexer configured to multiplex more than one communication channel into the beam. 
     
     
       11. An optical communication transceiver system as in  claim 10 , wherein the optical multiplexer is configured to perform at least one of the following: (1) polarization multiplexing, (2) time division multiplexing, (3) wavelength division multiplexing. 
     
     
       12. An optical communication transceiver system as in  claim 1 , further comprising an optical amplifier configured to increase the output power of the first modulated optical signal before it is transmitted to the remote optical communication transceiver system. 
     
     
       13. An optical communication transceiver system as in  claim 12  wherein the optical amplifier comprises at least one of an optical pre-amplifier, a semi-conductor optical amplifier, an erbium-doped fiber amplifier, and an erbium-ytterbium doped fiber amplifier. 
     
     
       14. An optical communication transceiver system as in  claim 1 , the system further comprising:
 at least one optical fiber disposed between any first one of a group of components and a second one of the group of components, the group of components comprising the USPL source, the pulse a pulse multiplier module, the optical an optical modulator element, the optical an optical multiplexer module, the optical an optical amplifier, and 
 
       wherein the at least one optical fiber is configured to guide the beam from the first one of the group of components to the second one of the group of components. 
     
     
       15. An optical communication transceiver system as in  claim 2 , the system further comprising:
 at least one optical fiber disposed between any first one of a group of components and a second one of the group of components, the group of components comprising the USPL source, the pulse a pulse multiplier module, the optical an optical modulator element, the optical an optical multiplexer module, the optical an optical amplifier, and 
 
       wherein the at least one optical fiber is configured to guide the beam from the first one of the group of components to the second one of the group of components. 
     
     
       16. An optical communication transceiver system as in  claim 1 , further comprising a second USPL source supplying a second beam of light pulses to the optical transceiver system, the second USPL source serving as a tracking and alignment beacon to determine or verify a target point for the transmitted modulated optical signal at the remote transceiver system. 
     
     
       17. An optical communication transceiver system as in  claim 16 , wherein a tracking and alignment beacon signal is generated within the modulated optical signal, the tracking and alignment beacon signal being used to determine or verify a target point for the transmitted modulated optical signal at the remote receiving system optical communication transceiver system. 
     
     
       18. An optical communication transceiver system as in  claim 10 , further comprising a polarization dependent multiplexer component that multiplexes optical signals of differing polarization states before transmission of the modulated optical signal to the second optical communication transceiver system. 
     
     
       19. An optical communication transceiver system as in  claim 10 , further comprising a polarization dependent de-multiplexer component that de-multiplexes optical signals of differing polarization states received as a second modulated optical signal from the second optical communication system. 
     
     
       20. An optical communication transceiver system as in  claim 10  claim 19, wherein the de-multiplexed optical signals are each interfaced to a different optical network for network usage. 
     
     
       21. An optical communication transceiver system as in  claim 1  wherein this transceiver the optical communication transceiver system is configured to detect atmospheric elements enabling analysis of a backscattered signal of an air-borne particulate signature of the atmospheric elements to enable adjustment of the beam generated by the USPL source to enhance atmospheric penetration. 
     
     
       22. An optical communication transceiver system as in  claim 21  wherein the detected atmospheric elements further comprise aerosols, fog, and scintillation effects. 
     
     
       23. An optical communication transceiver system as in  claim 21  further comprising a spectrographic analysis component for analyzing spectroscopic information extracted from the backscattered signal.