All-optical timing restoration

Apparatus for retiming a sequence of input pulses in an optical transmission medium in accordance with a reference sequence of pulses, comprising

• means for shifting the frequency of pulses in said input sequence of pulses due to the presence of said reference sequence of pulses, and
• means for advancing or retarding the pulses in said input sequence as a function of said pulse frequency.

Apparatus in an optical communications system for altering the timing in a series of input pulses in accordance with a series of essentially orthogonally polarized reference pulses, including

• a nonlinear material receiving said input pulses and said series of essentially orthogonally polarized reference pulses, said nonlinear material arranged to shift the frequency of said input pulses as a result of the presence of said reference pulses in said material, and
• a dispersive delay line receiving said input and reference pulses, said delay line arranged to translate said frequency shift produced by said nonlinear material into a corresponding time shift.

In an optical communications system, a method of restoring the timing in a series of input pulses with a first polarization orientation in accordance with a series of reference pulses with a second polarization orientation orthogonal to said first polarization, said method comprising the steps of

• applying said input pulses and said reference pulses to a nonlinear material having negligible walk-off and having a nonlinear index of refraction n.sub.2 ;
• and
• applying pulses output from said nonlinear material to a delay line having anomalous Group Velocity Dispersion (DVD) is n.sub.2 is greater than 0 and normal GVD if n.sub.2 is less than 0.

A method of retiming a sequence of input pulses in an optical transmission medium in accordance with a reference sequence of pulses, comprising the steps of

• shifting the frequency of pulses in said input sequence of pulses due to the presence of said reference sequence of pulses, and
• advancing or retarding of pulses in said input sequence as a function of said pulse frequency.

In an optical communications system, a method of altering the timing in a sequence of input pulses in accordance with a series of essentially orthogonally polarized reference pulses, including the steps of

• shifting the frequency of said input pulses as a result of the presence of a sequence of essentially orthogonally polarized reference pulses, by applying said input pulses and said reference pulses to a nonlinear material, and
• translating said frequency shift produced by said nonlinear material into a corresponding time shift by applying pulses output from said nonlinear material to a dispersive delay line.