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Fiber Optic Network Design. Class 8 C. S. Yan , X. Wu, M. Y. Li Dept. of Opt. Engr., ZJU 2013. Content. Introduction Development of optical fiber communication Bottlenecks Basic theory of COC Advantages, Principles, Structures and types DPSK DP-QPSK

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Fiber optic network design

Fiber Optic Network Design

Class 8

C. S. Yan, X. Wu, M. Y. Li

Dept. of Opt. Engr., ZJU

2013


Content

  • Introduction

    • Development of optical fiber communication

    • Bottlenecks

  • Basic theory of COC

    • Advantages, Principles, Structures and types

    • DPSK

    • DP-QPSK

  • Simulation of DPSK system by Optisystem

    • Pulse generation

    • Sequence decoder

    • Balanced receiver

  • Exercise today

  • Reference


Introduction

  • Higher Spectral Efficiency

  • Higher Data Rates

  • Higher Receiving Sensitivity


Introduction

Development process on optical transmission rate and transmission distance product for thirty years

bottlenecks

Revolution?

Moore's Law


Introduction

Development of optical fiber communication in the earlier years


Introduction

What is the bottlenecks for DWDM

1. Chromatic dispersion

2. polarization mode dispersion


Introduction

What is the bottlenecks for DWDM

3. Nonlinear effect

4. Electronic rate

When >30GHz,limited by electronic circuit and ADC chip


Introduction

4x

40Gb/s

delayed

S

1x 160Gb/s

How to break through the bottlenecks

——Optical Time Domain Multiplexing (OTDM)?

Electronic signals

Optical signals


Introduction

The advantages of OTDM


Introduction

The Disadvantages of OTDM

  • High price

    • Ultra-narrow optical pulse laser

    • Optical clock extraction and de-multiplexing

  • Severe nonlinear effects


Introduction

160Gb/s

160Gb/s

160Gb/s

WDM multiplexerof Add-Drop

OTDM add-drop

4 x 40Gb/s

40Gb/s

40Gb/s

4 x 40Gb/s

160Gb/s

4 x 40Gb/s

WDM demultiplexer of Add-Drop

OTDM demultiplexer

160Gb/s

4 x 40Gb/s

OTDM multiplexers

160Gb/s

160Gb/s regenerated

Combination of OTDM and WDM


Basic theory of coherent optical communication

How to breakthrough?

COC?

PhaseFrequencyPolarization Modulation

Amplitude Modulation

WDM

OTDM

Coherent Optical Communication


Basic theory of coherent optical communication

Opportunities come again COC

  • 2004, M. G. Taylor, PTL, Proposed to restore the signal using DSP, Digital coherent receiver technology

  • 2004, 20Gbit/s, QPSK system

  • solve the problem of channel attenuation

  • But hard to large scale Commercial

  • Replaced by EDFA in the 1990s

2002, R. A. Griffin (UK), DQPSK




Basic theory of coherent optical communication

The principle of COC

  • Detector Responsivity

  • Optical power



Basic theory of coherent optical communication

Structures and types of coherent receivers

(Differential phase shift keying)

(Quadrature Amplitude Modulation)


Basic theory of coherent optical communication

Signal Modulation of Differential phase shift keying (DPSK)

  •  phase change between 0 and 1 code


Coherent demodulation process of DPSK

Basic theory of coherent optical communication


Basic theory of coherent optical communication

Modulation formats comparison of coherent receivers

100Gbit/s

OSNR=0.2dB

50GHz channel spacing


Basic theory of coherent optical communication

Modulation formats comparison of coherent receivers

Dispersion can be compensated by DSP. For the same dispersion, it has different requirement for the computing power of the DSP (serials)

After 1600km transmission in standard single-mode fiber


Basic theory of coherent optical communication

Coherent receiver of Dual-polarization quadrature phase shift keying (DP-QPSK)

Balanced receiver

Demodulation

Polarization separation

TIA: Trans-impedance amplifier

Phase  intensity

Optical  Electrical


Basic theory of coherent optical communication

90 phase shift mixer of DP-QPSK

Optical fiber type

Free space type


Basic theory of coherent optical communication

90 phase shift mixer of DP-QPSK

LiNbO3 waveguide type

Si-based monolithic integration

Bell Lab 2010


Basic theory of coherent optical communication

90 phase shift mixer of DP-QPSK

Si-based monolithic integration type

Furukawa

InP-based monolithic integration type

Bell Lab 2011


Basic theory of coherent optical communication

90 phase shift mixer of DP-QPSK

Major international manufacturers of 100Gbit / s coherent receiver


Basic theory of coherent optical communication

90 phase shift mixer of DP-QPSK

Physical map of InP based monolithically integrated coherent receiver by HHI and U2T


Dpsk pulse generation
DPSK—pulse generation

Simulation of DPSK system by Optisystem software

Constellation

diagram


M ary pulse generator and threshold detector
M-ARY pulse generator and Threshold detector

Simulation of DPSK system by Optisystem software

input M-ary signal

pulse position

bit period

linear gain

duty cycle

parameter Bias

if the signal input has a value of -3.3, the output level will be -3, since -3.3 is between -3.5 and -1.5.


Dpsk pulse generation and decoding
DPSK—pulse generation and decoding

Simulation of DPSK system by Optisystem software


Dpsk sequence decoder
DPSK sequence decoder

Simulation of DPSK system by Optisystem software

The DPSK decoder will calculate the value of i from the phase difference between consecutive signals k and k-1:


Dpsk sequence decoder1
DPSK sequence decoder

Simulation of DPSK system by Optisystem software

Assuming ϕ=0, if bits per symbol (n) equals 2, and M=4, then the values for I and Q will be:

Assuming ϕ=0, if bits per symbol (n) equals 3, and M=8, then the values for I and Q will be:


Balanced receiver
Balanced receiver

Simulation of DPSK system by Optisystem software


Balanced receiver1
Balanced receiver

Simulation of DPSK system by Optisystem software

Eliminate intensity noise, improve sensitivity


Exercise today

Set up and study the system


Reference

  • 刘卫华. 用于100Gbit/s 相干通信的90°相移光混合器研究. 华中科技大学博士学位论文. 2012

  • 王甲琛. 基于FPGA的DPSK调制解调技术的设计与实现. 西安电子科技大学硕士学位论文. 2010


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