Photo: ESA Fiber-Optic Transceivers for High-speed Digital Interconnects in Satellites ICSO conference, 9 Oct 2014 Mikko Karppinen (mikko.karppinen@vtt.fi), V. Heikkinen, K. Kautio, J. Ollila, A. Tanskanen VTT Technical Research Centre of Finland Copyright 2014, VTT
2 Outline Motivation Why optical links for spacecraft Technology roadmap Transceiver technologies Manufacturing and device selections SpaceFibre links Parallel optical links Future intra-system interconnections Conclusions
3 MOTIVATION
4 Novel payloads call for high-speed intra-system communications on-board satellites High-performance scientific & observation instruments, such as: synthetic aperture radars, high-resolution cameras, fast image compression processors Increased throughput on telecom satellites with flexible and broadband payloads: multi-beam coverage, 100's of channels => Increasing on-board processing for filtering, switching and beam-forming.
5 Answer is to use optical communications Main advantages of fiber-optic links on satellite payloads: Lightweight cabling, immune to EMI High-bit rates (good signal quality) Removes distance limitations Photo: ESA Weight costs Opto vs copper: mass & volume savings => Need robust multi-gigabit optical interconnection components which have low power dissipation (due to tight power constraints on satellite) survive hostile environment, with >15 years lifetime, including: Vibrations and shocks Wide temperature range Radiation hardened
6 Towards wide use of on-board optical interconnections Space industry and European Space Agency are pushing the development of digital optical data links ESA s roadmap: DAS Photonics Low/medium rate links, Active optical cables (replacing copper) Thales Alenia Space Multi-channel high-bit-rate interconnects for on-board processors SpaceFibre Generic multi-gigabit link Optical harness on SMOS (launched 2009, 1 st extensive utilization by ESA)
7 TRANSCEIVER TECHNOLOGIES
8 Optoelectronics for harsh environments VTT s photonics integration & packaging competences: High-speed electronics integration Robust metal-ceramic photonics packaging with hermetic optical feedthroughs Design: electronics, optics, mechanical, thermal Manufacturing of circuit boards High-precision Assembly Characterisation and testing Ceramic micromodule platform
9 SpaceFibre High-Speed Fibre-Optic Link ESA promotes SpaceFibre as high-speed extension to SpaceWire standard: Objective is to provide symmetrical, full-duplex, point-to-point communication with 1 10 Gbps data rates over 100 m, suitable for satellite payloads VTT has developed transceiver components for SpaceFibre, based on: 850-nm VCSEL lasers: Lowest power-per-bit efficiency of the short range links; high integration density; mature; reliable; radiation tolerant 50/125 µm silica fiber: enough bandwidth, rather easy optical coupling 1 st gen (3 Gbps) SpaceFibre prototype was completed in 2006 Engineering Model proto of (6.25 Gbps) SpaceFibre transceiver
10 VTT s SolidOpto SPFI-003-6G 6.25 Gbps 850-nm Transceiver for Harsh Environment Up to 6.25 Gbps full-duplex data link for short range applications Protocol independent; but compatible with SpaceFibre physical layer Power consumption 210 mw (typical) 50/125 µm multimode fiber pigtails CML input VCSEL driver VCSEL Optical fibre Photo diode TIA & LIA CML output CML output TIA & LIA Photo diode Optical fibre VCSEL VCSEL TIA driver & LIA CML input Transceiver module Transceiver module SolidOpto SPFI transceiver with Radiall LuxCis connectors Data link functional diagram
11 VTT s 6.25 Gbps SpaceFibre Transceiver Structure Kovar frame VCSEL TOSA (SiGe driver on package carrier) Ceramic carrier (LTCC) SolidOpto SpFi Transceiver without metal lid ROSA with InPbased Rx IC Fibers Receiver VCSEL Laser driver Thermal design Bottom side of transceiver package (dimensions 17 x 17 x 5 mm 3 )
12 Optical Coupling: VCSEL/PD to Fiber Robust coupling to flip-chip device using ceramic circuit board 1. VCSEL chip aligned with hole (optical via) and flip-chip bonded. 2. Fiber passively aligned and supported to the hole from the other side. Au-stud or AuSn-solder flip-chip bump LTCC multilayer circuit substrate VCSEL / PD array chip Adhesive Fiber 5 4 3 2 1 Note: Au thermo-compression flip-chip joint passed temp cycling tests: -55 C +125 C, total 500 cycles => no failure or change in shear strength
13 Hermetic transceiver packaging and reliability Kovar frame and lid soldered to LTCC carrier Glass-metal fiber feedthrough using solder glass preform ferrule Photo by Diemat Corp Sealed packages passed the helium leak tests after been stressed with temperature cycling -55 +125 C up to 1000 cycles
14 Other environmental testing Radiations Passed specified total dose tests: Gamma radiation up to 100 krad Proton fluence 10 12 p/cm 2 (@ 60 MeV) Laser drivers used in the EM model showed tendency to latch-up effects at high dose of heavy ions (LET >35 MeV/mg/cm 2 ), however, the laser driver IC has been changed after that. Mechanical testing Vibrations: passed 50 g rms Shock: passed 3,000 g Thermal vacuum: passed
15 Functional Testing of SpaceFibre transceivers Clear eye opening >6.25 Gbps and BER <10-12 through specified operating temp range -40 +85 C (and wider) Tx optical 6.25 Gbps Complete link 6.25 Gbps Stressed 6.25 Gbps link eye at +90 ºC (ambient temp of Tx)
16 SpaceFibre SpaceWire interface compatibility Interoperability of VTT s SpaceFibre optical links with SpaceWire equipment was demonstrated by transmitting SpaceWire data at 2.5 Gbps through 100 m long SpaceFibre optical link. (demo by ESA, Patria Oyj and STAR-Dundee)
17 Towards high-bit-rate interconnects for on-board processor Generic hi-speed medium supporting inter-chip, inter-board and inter-equipment communications in telecom payload To overcome off-chip/board interconnect bottleneck: low power high throughput density Thales Alenia Space Parallel optic Inter-board links Inter-equipment links ( SpaceFibre ) Inter-chip / PCB-level interconnects ADC/DAC modules with fibre-optic interconnects
18 Parallel Optic (4+4 ch) Transceiver for harsh environments Up to 4x10 Gbps full-duplex data link for short distances Protocol independent; e.g. inter-board interconnects in on-board processor Power consumption ca 750 mw (=19mW/Gbps) Dimensions 17 x 17 x 9 mm 3 Hermetic package with multimode fiber ribbon pigtail Transceiver Fiber ribbon cable Transceiver Input (CML) Laser driver (4 channel) VCSEL laser array (4 ch) Photodiode array (4 ch) TIA & LIA (4 channel) Output (CML) 4 channel 4 channel Output (CML) TIA & LIA (4 channel) Photodiode array (4 ch) VCSEL laser array (4 ch) Laser driver (4 channel) Input (CML) 4 channel 4 channel Functional diagram SolidOpto OI2 transceiver with 8-fiber MTP connector PCB footprint
19 Parallel Optic (4+4ch) Transceiver Packaging TOSA & ROSA with 4-ch Rx & Tx ICs Ceramic carrier (LTCC)
20 Parallel Optic (4+4ch) Transceiver Specifications and Testing Component mass excluding pigtails 5 g Specified operating temperature range 10 +70 C (BER <10-12 ) Storage temperature range 55 +125 C Radiation-hard: gamma, proton 10Gbps: at +20 C +70 C -10 C (ambient temp)
21 Towards inter-chip optical I/O Optical interface should be as close as possible to ASIC/FPGA, in order to minimize overall power dissipation and complexity From hybrid integration up to chip-level Proposed 1 st generation solution: Integrate multi-channel fiber-optic I/O into the IC package Illustration of space-grade ASIC package with fibre-ribbon I/O s Functional diagram of I/O s
22 Ongoing research MERLIN project Multi-Gigabit, Scalable & Energy Efficient on-board Digital Processors Employing Multicore, Vertical, Embedded Optoelectronic Engines Project objectives include: Ruggedized optical transceiver engines with record-high data rate of 150 Gb/s wide temp range, low power Very dense integration by the use of: Multicore fibers Custom VCSEL & PD arrays Custom multi-channel ASICs More info: www.space-merlin.eu Transceiver Vision Multicore fiber ( OFS)
23 Summary Expanding needs for hi-speed interconnections on satellite payloads => Towards wide use of fiber-optic communications, benefits: High data rates; Lightweight cabling immune to interferences VTT developed high-bit-rate data links with transceivers based on: Advanced metal-ceramic photonics packaging 850-nm VCSELs and multimode fibers Components developed for intra-satellite communications so far: SpaceFibre fibre-optic transceivers (6.25 Gb/s) Parallel optical transceivers (4+4 x 10 Gb/s) Also developing inter-chip/package optical interconnects For instance, for ADC/DAC modules with optical interconnects Concepts for next-gen ASIC packaging with integrated optical I/O High-density, multi-channel
24 Acknowledgements to Our Project Partners:
25 For further information please contact: Mikko Karppinen Senior Scientist, Dr. Photonics Integration VTT Kaitoväylä 1, P.O. Box 1100 FI-90571 Oulu, Finland Tel. +358 20 722 2293 (direct/mobile) Fax +358 20 722 2320 mikko.karppinen@vtt.fi www.vtt.fi
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