The Operation and Power Budget of Amplified Optical Networks for Aerospace Applications. FOHEC Conference May 2010

Transcription

1 The Operation and Power Budget of Amplified Optical Networks for Aerospace Applications FOHEC Conference May 2010 BAE Systems / University of Strathclyde Henry White Walter Johnstone Craig Michie BAE Systems University of Strathclyde University of Strathclyde

2 Contents Introduction Optical Amplified Network Simulated Network Noise Sources Dynamic Range Experimental Work

3 CWDM Aerospace Networks Increase network bandwidth Dense Wavelength Division Multiplexing (DWDM) Coarse Wavelength Division Multiplexing (CWDM) 20 nm spacing Less susceptible to wavelength drift Use of uncooled devices (where possible!) Extended aerospace temperatures and harsh environments

4 Optical Amplified Network Transmitter Receiver Key Parameter Gain, NF, PP sat NF sat Booster Amplifier In-Line Amplifier Pre-Amplifier Location of Amplifier depends on overall system margin Trade-off between split loss and trunk loss Amplifier not always in optimum position due to installation considerations In-Line most likely situation

5 Optical Amplifier Many versions of optical amplifiers Erbium-Doped Fibre Amplifier (EDFA) Semiconductor Optical Amplifier (SOA) Fabry-Perot laser diode Gain up to 30 db Data rate transparent Small form factor Less expensive COTS device used Current Output Signal and Noise Active Regions and Waveguides Input Signal Input Facet

6 Optical Amplifier Suitability for CWDM systems ITU CWDM standard of 1260 to 1620 nm (low loss fibre transmission window) SOA EDFA: C-Band ( nm) L-Band ( nm) SOA: nm Advantages High Gain Wide Transmission Window Inexpensive Compact Data Transparent Easier Integration Disadvantages Noisy Low Temperature Range Polarisation dependent

7 Simulated Network α 1 α 2 The following setup was used for the analysis: The transmitter extinction ratio and power The loss before the amplifier (splitter / connector / trunk loss) Amplifier gain, saturation power and noise figure Post amplification filtering restrict wavelength Post amplification loss (splitter / connector / trunk loss) Receiver performance, including noise sources

8 Noise Sources System performance Signal-to-Noise Ratio SNR= Average_ Signal_ Power Noise_ Power = 2 I p 2 tot σ Total Noise σ 2 Tot = σ σ σ σ σ T + S + 2 ASE + S ASE + 2 ASE ASE Combines contributions from: Thermal Noise Shot Noise ASE- Shot Noise ASE-ASE Beat Noise Signal-ASE Beat Noise

9 Modelled Results 40 Output Attenuation (db) Gain Unamplified 15 db 18 db 20 db 22 db 25 db Input Attenuation (db)

10 Experimental Setup

11 Experimental Results 35 Gain 100 ma = 18 db SOA Maximum Output Attenuation (db) ma 200 ma 250 ma = 20 db = 21 db = 22 db SOA Maximum Input Attenuation (db)

12 Comparison of Model to Experimental Results Output Attenuation (db) Modelled 18 db 20 db 22 db Experimental 100 ma (18 db) 150 ma (20 db) Input Attenuation (db) 250 ma (22 db)

13 TEC Control SOA mounted on Thermoelectric Cooler (TEC) Operational range of SOA: 10 C to 70 C Want extended temperature range -40 C to 120 C Maximum TEC power: 3.5 W Gain dependent on temperature

14 Temperature Dependency Dynamic Range of SOA at 150 ma 35 SOA Output Attenuation (db) degrees 25 degrees 40 degrees 70 degrees SOA Input Attenuation (db)

15 Power Budgets TEC Temperature TEC Power (W) C 20C 30C 40C 50C Ambient Temperature (C) 60C 70C

16 Conclusion Suitability of amplified optical networks for aircraft assessed Modelling optically amplified network Network layout Position of SOA Experimental Verification Amplified dynamic range Dependency on temperature SOA operational temperature range Extended operation with TEC Power consumption implications Model can be used to determine Operation in aerospace conditions System Implications