Demonstrating COTS Optical Fiber Transceivers for Intra-Satellite High-Speed Communications

Very hight throughput service satellite

By Jocelyn Jocelyn Lauzon, Guillaume Blanchette, and Pierre Cardinal -Reflex Photonics

Satellites are being deployed in different orbit configurations, for different applications, but most of them involve large data transfer such as real-time high-resolution images requiring at least 1.5Gbps per transmission.

In this presentation, we will demonstrate that parallel fiber optics transceivers are the best components to support the large data transfer applications found in intra-satellite communications.

Optical fiber optic transceivers are insensitive to electro-magnetic interference, they have limited weight, have small volumes and can offer an unbeatable transmission capacity to power consumption ratio. The satellite industry can benefit from the proven high-performance fiber optic transceiver technology that has already been in use for many years for harsh environment defense and avionics applications, by choosing Commercial Off-The-Shelf (COTS) fiber optic transceiver products.
From using these COTS products, rather than custom-made components, the satellite industry also benefits from much lower unit prices, for a field-tested technology. The only concern with these COTS products is their robustness to space environment specific requirements such as radiation hardness, temperature cycling in vacuum, outgassing and decompression; these requirements exceed the defense and avionics reliability requirements such as thermal fatigue, vibration, mechanical and thermal shocks. In this presentation, we will demonstrate it is possible to meet these extra space environment requirements, in addition to all other harsh environment requirements, with minimal technical adjustments to COTS fiber optics transceivers.

Large Bandwidth Satellite Programs

Very hight throughput service satellite

Digital transparent processor for VHTS (very high throughput service) Ka-band, 500 Gbps

•High-speed Internet
•In-flight connectivity
•Broadband connectivity to rural areas

Need for largest bandwidth technology available inside the satellite: optical fiber communications.

SES-17 Ka-HTS satellite

Ka-band, multibeam approach

Provide mobility customers with an unsurpassed ability to efficiently and flexibly modify their network in real-time.

  • Real-time high-resolution images require at least 1.5 Gbps per transmission

Optical fiber communications offer Tbps bandwidth capacities

Reflex Photonics Optical FiberTransceivers

Parallel optical fiber transceivers offer many benefits

Parallel optical fiber transceivers offer the following benefits

  • Reduced SWaP: size, weight and power
  • EMI insensitive
  • Large bandwidth
  • Multimode fiber (OM3/OM4), parallel optics: better adapted to high-reliability and short distance application
  • Point-to-point: best robustness vs capacity compromise
  • No integrated microcontroller to ensure radiation hardness
  • VCSEL laser sources offer better performance stability vs temperature (no Tcontroller)
  • COTS for reasonable cost: proven technology for defense and avionics applications

SWaP

  • Size: see drawing
  • Weight: from 3 g to 5 g depending on product variation
  • Power: ~1 W for 8 lanes, up to 12.5 Gbps/lane, −40°C to 100°C
LighABLE embedded transceiver
Drawing of SpaceABLE 50G and 150G
Drawing of SpaceABLE 50G and 150G

Specifications and  product variations

COTS (Commercial Off-The-Shelf) Product Variations

  • 4TRX (4+4), 12TX, 12RX and 12 TRX (12+12)
  • Up to 28 Gbps/lane
  • Different electrical interfaces
  • Different optical interfaces

Specifications

  • Optoelectronic circuit 100% sealed
  • Power budget offering optical fiber link longer than 100 m for BER 10-12
SapceABLE28

Electrical interface

LightABLE embedded transceiver LM Series

Surface mountable with ball-grid array (BGA)

Pluggable with MegArray

Screwable with land grid array (LGA)

Optical interface

All possible interface enables the MT ferrule for ribbon cable connection. Each product variation needs to be qualified for space applications requirements.

Proprietary MicroClip™ MT ferrule

MicroClip

LightABEL with screw-in electrical interface

Screw-in

The LightCONEX blind mate optical interconnect for VPX embedded computing systems, consists of a module connector and a backplane connector compatible with the VITA 66.4 standard.

OpenVPX

LightABLE pigtail electrical interface

Fiber pigtail

New SpaceABLE COTS Product Variations

  • Improved radiation resistance (Radhard)
  • Improved lifetime reliability
  • Same electrical interface variations (pin-out)
  • Same optical interface variations
  • Same footprint
  • Same external physical dimensions
  • Same packaging material construction
  • Minimal, but critical, optoelectronics circuit adjustments
The SpaceABLE SL embedded optical modules are rugged devices offering high bandwidth (greater than 150 Gbps) in a chip-size package.

Mandatory  Tests for Aerospace and Defense Applications

Mechanical integrity tests (serial tests)

  • Vibration tests in all 3 axes as per MIL-STD-883, Method 2007.3, with a peak acceleration of 20 g between 20 Hz and 2000 Hz for 16 minutes per axis,
  • Mechanical shock tests in all 6 directions/orientations as per MIL-STD-883, Method 2002.4, 500 g shock with a half-sine pulse duration of 0.5 ms with 5 repetitions in each orientation
  • Thermal shock tests as per MIL-STD-883, Method 1011.9, 20 cycles between 0°C and 100°C with 10 minutes dwell time and transient time less than 5 seconds.

Test must be conducted on at least 11 units from at least 2 independent fabrication lots.

Mechanical integrity tests

Environmental stress tests

  • 1000 thermal cycles between -40°C and 85°C with ramp rates of 10°C/minutes and dwell times of 5 minutes
  • Damp heat as per MIL-STD-202, Method 103B at 85°C and 85 % humidity for 500 h
  • Reflow (when applicable), cold storage, temperature cycling (serial tests):
    • Pre-bake at 125°C for > 12 h followed by 3 consecutive reflow simulations
    • Cold storage as per MIL-STD-810, Method 502.5, Procedure 1, Climatic conditions C3, -57°C for 168 h
    • 100 thermal cycles between -57°C and 100°C with ramp rates of 10°C/minutes and dwell times of 5 minutes

Any visual inspection anomaly or significant performance degradation is a qualification failure

Environmental stress tests

Lifetime Tests

  • Life tests conditions are inspired by the steady-state life test descriptions (MIL-STD-883, Method 1005.8)
  • Duration more than 2000 h, case temperature 100°C, bias current exceeding operating conditions
  • Constant monitoring and interim tests
  • Acceptable power degradation no more than 1dB
  • Measured average output power degradation was much less than 1dB
MTBF > 20 years
Accelerated life testing done on SpaceABLE

Live test

  • Live temperature cycling
  • Live fiber pull tests
  • Live random vibration
Live test setup configuration.

BER 10-12 limit adjusted through attenuators

LightABLE being subjected to live fiber pull test

Live fiber pull tests 1 kg

Live random vibration in 3 axes as per MIL-STD-883, Method 2026, Test Condition II J, 41.7 grms between 20 Hz and 2000 Hz for 10 h per axis

Validation of the optical and electrical interface

Validation of backplane plug-in optical interface

Blind-mate board-edge active optical connectors

Additional test requirements:

  • Salt fog tests as per MIL-STD-1344, Method 1001, Test C
  • Sand and dust as per MIL-STD-810, Method 510.4, ProcedureI
  • Durability with misalignment tests as per MIL-M-28787
None of these tests being relevant for space applications
Open VPX logo
LightCONEX blind mate interconnect

Aerospace and Defense applications

Military aircraft sub-systems; nervous system for intelligent aircrafts
Military aircraft sub-systems; nervous system for intelligent aircrafts.
High performance embedded computers
High performance embedded computers
Active electronically scanned array radar
Active electronically scanned array radars
High resolution surveillance cameras
High resolution surveillance cameras

Additional Requirements for Space Applications

TTF1% > 20 years vs MTBF > 20 years

Note that GEO requirements to meet both LEO and GEO specifications:

  • LEO TTF1% 5-10 years, total radiation dose 10krad
  • GEO TTF1% 10-20 years, total radiation dose 100krad

Additional requirements 

  • Outgassing
  • TVAC
  • Decompression
  • Radiation Tests
    • TNID
    • TID
    • Heavy Ions

Outgassing

  • As per ECSS-Q-ST-70-02C with pass criteria: RML% ≤ 1,00%, CVCM ≤ 0,10%

Rapid Decompression

  • As per MIL-STD 810G, Method 500.5, Test condition III: 2 438 to 15 850m, transfer time < 15s, soak 1 hour at 15 850m
For these tests to be considered a success, no significant performance difference between tests performed before and after decompression tests

TVAC (live thermal vacuum testing)

  • Simulate operation under vacuum
  • Monitor BER during the cycles
  • Pressure: ≤5*10-5 hPa (approx. 1*10-5ounce/in2)

Radiation Resistance Tests

TNID: Total Non-IonizingDose - Proton

  • 100 MeV proton energy beam in 50x50-mm
  • With radiation steps of: 5e10, 1e11, 5e11, 1e12, and 5e12 p/cm2
  • 168 h at 100°C post annealing step
  • Functional tests after exposure

TID (total ionizing dose – Gamma Rays Co60) tests

As per ECSS 22900

  • The Gamma-ray dosing rate should be set at roughly 72 rads/h
  • The cumulative doses for each of the exposure levels will be: 10, 20, 30, 50, 70, and 100 krads
  • There will be a post-radiation annealing step of 24 h at 22°C
  • There will be a further annealing of 168 h at 100°C

Heavy Ions Tests

Single Event Effect (SEE) as per ECSS 25100

Devices tested at 2 temperature / voltage conditions:

  • 85°C @ 3.4 V
  • Room temperature  @ 3.2 V

5 heavy ion beams:

  • Test 1: Ho (highest energy)
  • Test 2: Cu; Test 3: Ar; Test 4: Ne; Test 5: N (lowest energy)
  • Fluence: 107 ions/cm2
  • Active DUT: measuring events/errors
  • Creating cross section vs LET (linear energy transfer) curve
Additional requirements for space applications
Thermal vacuum testing (TVAC)
Thermal vacuum testing (TVAC) cycling
Heavy ions tests

Conclusions

  • The need for intra-satellite optical communications is a reality
  • Highly-reliable optical fiber transceivers using parallel optics over OM3/OM4 multimode fibers is the best technology to support intra-satellite optical communications
  • COTS optical fiber transceivers have proven they can meet space applications requirements with minimal, but critical, adjustments

Acknowledgements

The authors would like to thank their colleague David Rolston, Nikos Karafolas, and Iain McKenzie of ESA and Thales Alenia Space for fruitful discussions.