Time and wavelength-shifted dynamic bidirectional system

Abstract

In one embodiment, a bidirectional optical network is disclosed, in which an incoming/downstream modulated optical signal(s) of a particular wavelength may carry content from a headend to a subscriber. An incoming/downstream unmodulated continuous wave optical signal(s) from the headend may be time-shifted (i.e., time delayed with respect to just received incoming/downstream optical signal(s)), collected, modulated and sent back as return/upstream optical signal(s) from the subscriber to the headend. The return/upstream optical signal(s) may have the same wavelength or a slightly shifted wavelength relative to incoming/downstream optical signal(s). In some embodiments, wavelength, bandwidth, subscriber priority and service (content) provider may be fixed, dynamically, or statistically assigned.

1 .- 30 . (canceled) 
     
     
         31 . A device, comprising:
 a photodiode configured to convert a first modulated form of a downstream optical signal into an electrical signal;   a modulator configured to modulate an unmodulated form of the downstream optical signal to produce a second modulated form of the downstream optical signal; and   a wavelength shifter configured to adjust a wavelength of the second modulated form of the downstream optical signal to produce an upstream optical signal.   
     
     
         32 . The device of  claim 31 , further comprising:
 a circulator configured to facilitate reception of the downstream optical signal and transmission of the upstream optical signal over the same optical fiber.   
     
     
         33 . The device of  claim 31 , further comprising:
 an optical power splitter configured to direct the first modulated form of the downstream optical signal to the photodiode and the unmodulated form of the downstream optical signal to the modulator.   
     
     
         34 . The device of  claim 33 , further comprising:
 an optical amplifier coupled to the optical power splitter, wherein the optical amplifier is configured to amplify the unmodulated form of the downstream optical signal.   
     
     
         35 . The device of  claim 31 , further comprising:
 a noise reduction filter configured to filter noise from the upstream optical signal.   
     
     
         36 . The device of  claim 31 , wherein the device is configured to receive the unmodulated form of the downstream optical signal during a time slot, and wherein the modulator is configured to modulate the unmodulated form of the downstream optical signal for a portion of the time slot, wherein the portion is less than a length of the time slot. 
     
     
         37 . The device of  claim 31 , wherein the device is a subscriber device configured to convey the upstream optical signal to a headend within an optical network. 
     
     
         38 . The device of  claim 31 , wherein the photodiode is a tunable photodiode. 
     
     
         39 . An optical system, comprising:
 a subscriber device configured to:   convert a first modulated form of a downstream optical signal into an electrical signal;   modulate an unmodulated form of the downstream optical signal to produce a second modulated form of the downstream optical signal; and   adjust a wavelength of the second modulated form of the downstream optical signal to produce an upstream optical signal.   
     
     
         40 . The optical system of  claim 39 , wherein the subscriber device is configured to receive the downstream optical signal and transmit the upstream optical signal over the same optical fiber. 
     
     
         41 . The optical system of  claim 39 , wherein the subscriber device includes an optical power splitter configured to direct the modulated form of the downstream optical signal to a photodiode of the subscriber device and the unmodulated form of the downstream optical signal to a modulator of the subscriber device. 
     
     
         42 . The optical system of  claim 39 , wherein the subscriber device includes a noise reduction filter configured to filter noise from the upstream optical signal. 
     
     
         43 . The optical system of  claim 39 , wherein the subscriber device is configured to:
 receive the first modulated form of the downstream optical signal during a first time slot;   and receive the unmodulated form of the downstream optical signal during a second time slot distinct from the first time slot.   
     
     
         44 . The optical system of  claim 39 , further comprising:
 a headend configured to communicate with the subscriber device.   
     
     
         45 . A method, comprising:
 converting, at a photodiode of a communication device, a first modulated form of a downstream optical signal into an electrical signal;   modulating, by the communication device, an unmodulated form of the downstream optical signal to produce a second modulated form of the downstream optical signal; and   adjusting, by the communication device, a wavelength of the second modulated form of the downstream optical signal to produce an upstream optical signal.   
     
     
         46 . The method of  claim 45 , further comprising:
 the communication device receiving the downstream optical signal over an optical fiber; and   the communication device transmitting the upstream optical signal over the optical fiber.   
     
     
         47 . The method of  claim 46 , further comprising:
 the communication device applying a noise reduction filter to the upstream optical signal prior to transmitting the upstream optical signal.   
     
     
         48 . The method of  claim 46 , further comprising:
 the communication device receiving the first modulated form of the downstream optical signal during a first time slot; and   the communication device receiving the unmodulated form of the downstream optical signal during a second time slot distinct from the first time slot.   
     
     
         49 . The method of  claim 45 , further comprising:
 the communication device amplifying, via an optical amplifier, the unmodulated form of the downstream optical signal.   
     
     
         50 . The method of  claim 45 , wherein the communication device is a subscriber device in an optical network.