US 6,724,484 B2Granted

Format insensitive and bit rate independent optical preprocessor

AssigneeAlphion Corporation

InventorsJulio Martinez, Kwang Kim, Olga Nedzhvetskaya, Doruk Engin, Jiten Sarathy, Roman Antosik, Bharat Dave, Michael Evans, David Lidsky, Ronald Simprini, Boris Stefanov, Tan Thai

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Abstract

A method and circuit are presented for an all-optical format independent preprocessor that processes an arbitrary optical input signal by converting a NRZ signal to a PRZ signal, or if the input optical signal is RZ, by merely amplifying it. The method involves subtracting a delayed copy of the signal from the original, thereby effectively doubling its frequency, and inserting a pulse at each transition of the original signal, whether rising or falling. In a preferred embodiment this stage is implemented via an integrated SOA in each arm of an asymmetric interferometric device. The asymmetry consists of a delay element in one arm. In a preferred embodiment the entire device is fabricated on a semiconductor substrate, allowing for compactness as well as minimization of interconnectivity losses and overall power consumption. The output of the preprocessor, having a significant frequency component at its original clock rate, can then be fed to a clock recovery stage for all-optical clock recovery.

Claims11

Dependent claims

A method, comprising:

proccssing an optical signal in NRZ format so as to cause it to have a high spectral component at its original clock frequency by dividing the optical signal into two segmental signals, applying a variable phase delay to a first segmental signal, amplifying each of the segmental signals by an optical amplifier and recombining the amplified segmental signals in a destructive interference.
wherein said optical amplifier is a semiconductor device comprising:
an InP substrate of a first doping type;
a first InP layer of the first doping type disposed on said InP substrate;
a second InP layer of the first doping type disposed upon on said InP layer;
A first InGaAsP waveguide region laterally disposed on said second InP layer of the first doping type, said first InGaAsP waveguide region having a width less than that of the first InP substrate of the first doping type, first InP layer of the first doping type and second InP layer of the first doping type;
an active strained multiple quantum well region laterally disposed on top of said first waveguide region, having essentially the same width as said first waveguide region;
a second InGaAsP waveguide region laterally disposed on top of said strained multiple quantum well region, having essentially the same width as said first waveguide region;
a third InP layer of the first doping type, laterally disposed on top of said second waveguide region, and extending downward, in the direction of said substrate along the sides of said active region and said first waveguide region, having a width essentially equal to the substrate and the first InP layer of the first doping type and second InP layers of the fist doping type;
a first InP layer of a second doping type laterally disposed above said third InP layer of the first doping type, having essentially the same width as said first waveguide region and as said strained multiple quantum well region;
a second InP layer of a second doping type laterally disposed on said first InP layer of the second doping type, having essentially the same width as said first InP layer of the second doping type;
a contact layer laterally disposed above said second InP layer of the second doping type;
and
a metal electrode disposed above said contact layer.

11 more elements

A method for processing a single optical signal in NRZ format in an all-optical clock recovery system to have a high spectral content, comprising the steps of:

(a) splitting the single optical signal into a first and a second branch signal;
(b) amplifying the first branch signal and the second branch signal, each by an optical amplifier;
(c) applying a phase delay to said first branch signal;
and
(d) combining the amplified and phase-delayed first branch signal and the amplified second branch signal to produce a destructively interfered resultant single optical signal,
wherein said optical amplifier is a semiconductor device comprising:
an InP substrate of a first doping type;
a first InP layer of the first doping type disposed on said InP substrate;
a second InP layer of the first doping type disposed upon said first InP layer;
a first InGaAsP waveguide region laterally disposed on said second InP layer of the first doping type, said first InGaAsP waveguide region having a width less than that of the first InP substrate of the first doping type, first InP layer of the first doping type and second InP layer of the first doping type;
an active strained multiple quantum well region laterally disposed on top of said first waveguide region, having essentially the same width as said first waveguide region;
a second InGaAsP waveguide region laterally disposed on top of said strained multiple quantum well region, having essentially the same width as said first waveguide region;
a third InP layer of the first doping type, laterally disposed on top of said
second waveguide region, and extending downward in the direction of said substrate along the sides of said active region and said first waveguide region, having a width essentially equal to the substrate, and the first InP layer of the first doping type and second InP layers of the first doping type;
a first InP layer of a second doping type, laterally disposed above said third InP layer of the first doping type, having essentially the same width as said first waveguide region and as said strained multiple quantum well region;
a second InP layer of the second doping type laterally disposed on said first InP layer of the second doping type having essentially the same width as said first InP layer of the second doping type;
a contact layer laterally disposed above said second InP layer of the second doping type;
and
a metal electrode disposed above said contact layer.

16 more elements

Dependencies are inferred from the claim text.

Facts

Application: 10/195,699Filed 15 Jul 2002 · division
Priority: 4 May 2001
Published: US 2002/0041428 A15 Dec 2002
Granted: 20 Apr 2004
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

H04B 10/299
In which processing or amplification is carried out without conversion of the main signal from optical form: signal waveform processing, e.g.…
H04L 7/0075
Arrangements for synchronising receiver with transmitter: with photonic or optical means
H04B
Transmission
H04L
Digital communication

Family

Application09/848,968Parent of this division · filed 4 May 2001
US 2002/0181085 A1Pre-grant publication · published 5 Dec 2002
US 6,570,697 B2Parent of this division
US 2002/0041428 A1Published application
US 6,724,484 B2This patent

From the US filing history. Foreign family members aren’t listed.