Semiconductor Optical Amplifiers in Avionics C Michie, W Johnstone, I Andonovic, E Murphy, H White, A Kelly

Semiconductor Optical Amplifiers in Avionics Significant advantages within Avionics context from use of optical communications networks bandwidth, EMI, significant weight savings Current systems limited to point to point, multimode This work Learn from terrestrial communications using COTS Focus on PONs – cost is critical Strategies towards WDM – minimal component inventory Key operational consideration Extended temperature range

Long Haul; DWDM systems maximise fibre bandwidth usage TXλ1TXλ1 TXλ2TXλ2 TXλNTXλN TXλXTXλX TXλXTXλX TXλXTXλX TXλXTXλX 40 wavelengths, 200 GHz spacing 10,40, 100+ Gbit/channel

Long Haul; DWDM systems maximise fibre bandwidth usage Wavelength specific transmitters –single wavelength, DFB –Temperature regulated Many wavelengths –inventory issues for Avionic system Temperature Control –increased power consumption Expensive for Avionics –not a flier!

Passive Optical Networks High bandwidth Access solutions Cost is critical – minimise number of components Minimise manufacturing specification Operate without cooling if possible Reflective Semiconductor Based Optical Amplifiers –RSOA – transmitter and amplifier using same component

CS- RSOA RSOAs as transmitters User end BLS P λ P λ

CS-RSOA RSOAs as transmitters User Broad Band Source P λ P BLS CS-RSOA

Avionics Link Simple link –500 m, 1 Gbit/s Single Broad band seed source –might need two ? Multiplexer, de-multiplexer Minimal cooling/heating

BLS Fibre Link Tx RSOA Rx Fibre Link Tx RSOA Rx 0.6 dB 0.8 dB 3.5 dB

RSOA Design InP:InGaAsP Buried Heterostructure Lateral Waveguide Tapers Tensile Bulk High back refectivity 0.88 Front facet AR coated RSOA in TO

TO-packaged S-band RSOA parametric tests Standard tests at 25ºC and 80mA

Dynamic Range Psat ~ 5 dBm, Gain > 20 dB so we need -15 dBm input to saturate Can get 0dBm/nm from COTS sources -5 dBm/nm is obtainable with lower power module –NB the above module needs to be cooled but it should be the only component within the system To get 12 dB dynamic range (allows 3dB plus of margin) we can allow gain/Psat drop with temperature

RSOA modulation experiments TO packaged devices on ETS evaluation board 50mA DC bias, 60mA modulation S band RSOA, CW injection at 1465 – 1530nm Stage temperature 25°C Modulation at 1.25 Gbps data rate with PRBS bit pattern The Rx - APD photoreceiver with limiting amplifier

Sensitivity, Output Power, Gain and Path Loss Capability at 1490nm and 25ºC ~30dB return path loss capability at -20dBm input

Sensitivity, Output Power, Gain and Path Loss Capability at 1580nm and 25ºC

Sensitivity, Output Power, Gain and PLC versus Wavelength at 25ºC -20dBm CW input power and 25ºC stage temperature Eye diagram at 1490nm

S, C and L band performance S-band deviceC-band device

RSOA with Broadband light source

Path Loss Capability TLS, BlS

High Temperature RSOA Design AlInGaAs Ridge Waveguide Single Polarisation High back refectivity 0.88 Front facet AR coated 0.01% RSOA in TO

Temperature Performance of RSOA Tuneable Laser RSOA Optical Spectrum Analyser Variable Attenuator Temperature Controlled Mount Evaluate Gain, NF, Psat as a function of temperature. Enables prediction of performance (Power budget for BER )

Packaged BH Temperature Characterisation

Chip on Carrier Ridge Temperature Characterisation

Temperature Characterisation

Conclusions WDM PONs enabled by RSOAs –TO packaged polarisation insensitive S band RSOA – ~1dB penalty at 1.25Gbit/s compared to commercial M-Z modulator High Temperature Operation AlInGaAs active region –Ridge waveguide design due to oxidation –Single polarisation –Potential to increase operating temperature to > 70 C –Much reduced cooling requirement