# Presentation: 925891

## Characterization of Commercial Optical Fiber Cables for Space Flight Environments at NASA Goddard Space Flight Center

***Melanie Ott***
- Sigma Research and Engineering
-  / Goddard Space Flight Center
- 301-286-0127, melanie.ott@gsfc.nasa.gov
- http://misspiggy.gsfc.nasa.gov/tva

- IMAPS/NEPP ATW May 24, 2000

## Outline

- Background
- Definitions
- Lessons Learned
- Characterization Testing on cable
- Results of Thermal Testing of COTS Cables
- MTP Ribbon Cable Assembly Characterization Results
- Optical Fiber Electron Scintillation Testing Results
- Optical Fiber Total Dose Radiation Testing
- Conclusion

## Background

- Goals of COTS Cable Characterization Program
- Cable assembly using Commercial-Off-the-Shelf Technology (COTS).
- Wide variety of products with parameters for usage.
- NASA wide use.
- Multimode and singlemode applications.
- Parnerships with vendors.
- Issues
- NASA qualified cable is obsolete.
- No more full qualification programs.
- Need for characterization of available COTS parts.
- Technological advancements.

## Optical Fiber Cable Definitions

- Core

- Cladding

- Core

- Cladding

## Optical fiber cable can have failures
Shrinkage of Fluoropolymers: Teflon & Tefzel (TFE, ETFE, PFA, FEP) - causes optical losses and reliability problems.
Connector/cable incompatibility
Destructive strength testing on fiber, post cabling.
Proof testing (100% on fiber) implemented properly during draw
Traceability of parts
Outgassing of acrylate coating, passes in configuration.
Clean terminations prior to testing and integration, inspect terminations
Use space flight parts only for space flight hardware.

- Lessons Learned

- Optical fiber cable can have failures
- Shrinkage of Fluoropolymers: Teflon & Tefzel (TFE, ETFE, PFA, FEP) - causes optical losses and reliability problems.
- Connector/cable incompatibility
- Destructive strength testing on fiber, post cabling.
- Proof testing (100% on fiber) implemented properly during draw
- Traceability of parts
- Outgassing of acrylate coating, passes in configuration.
- Clean terminations prior to testing and integration, inspect terminations
- Use space flight parts only for space flight hardware.

## Characterization of Cable and Assemblies

- Technology Validation of the COTS part: knowledge of the failure mechanisms associated with part and good knowledge of environment for use.
- Testing to bring out known failure mechanisms.
- Radiation, Vibration, Thermal, Outgassing, Strength.
- Specify environment for cable assemblies, post testing.
- Recommendations on how to bring product to the next harsher environment.
- Some generic testing for a variety of missions based on a common environment.

## Thermal Testing of COTS cables

- Thermal Test 1: -30 °C to 140 °C, 5 min dwell, 1 °C /min, 28 & 60 cycles
- Spectran Flightguide,
- W.L.Gore 8838 (prototype I) & FON1008
- Brand Rex 1008
- Northern lights: 1-HYMC62CFD, 1-HYMC10C
- Thermal Test 2: -55°C to +125°C, 20 min dwell, 2°C /min, 72 cycles
- W.L. Gore FON1004 (prototype II)
- Brand Rex 1614
- Brand Rex 1008
- Northern Lights (RIFOCS) H06
- Northern Lights (RIFOCS) HL1

## Testing:  Cable Component Shrinkage from Temperature Cycling

- -30 to 140 degrees C, 1 degree C/min, 5 min dwell at  extremes

- Generic Environmental Parameter Testing:
- Spectran Flightguide, Brand Rex 1008, W.L.Gore 8838

## Optical Testing for Shrinkage From Thermal Cycling

- Generic Environmental Parameter Testing

## Summary of Test Results and Cable Parameters from Generic Shrinkage Testing, 

- Thermal Environment: -30 to 140 degrees C, 1 degree C/min, 5 min dwell at  extremes
- General conclusions:
- -  Large outer diam = more shrinkage.
- -  Shrinking reduced to less than 0.1% after 60 cycles.
- -  FON 1008 good optical stability, Spectran Flightguide: construction stability.
- -  Hytrel usually a poor choice for a thermally stable jacket.

## Thermal Optical Cable Testing Description and % Shrinkage Summary, 3m lengths, -55°C to +125°C, 20 min dwell, 

## Thermal Cycling Test Results COTS and Space Flight Cables

- -55°C to +125°C, 20 min dwell at extremes, 2 °C/min

## Thermal Cycling Length Shrinkage and Optical Performance Summary, -55°C to +125°C, 72 cycles

## FODB COTS Application, MTP connector with 12 Channel FO Ribbon Cable Assembly

- Pictures

## MTP Ribbon Cable Assembly Characterization3 m length, 1300 nm

- Random vibration testing: insitu monitoring of one channel/test and post measurements of all 12 channels.
- 	(14.1 grms, 1 minute/axis)
- Thermal testing (insitu testing of one channel/test):
- 30 cycles, -20 °C to +85 °C, 1 °C /min.
- 42 cycles, -20 °C to +85 °C, 3 °C /min up, 2 °C /min down.
- Random vibration testing 2: insitu monitoring of one channel/test and post measurements of all 12 channels.
- 	(20 grms, 3 minutes/axis)

## MTP Ribbon Cable Assembly Testing Summary

- Twelve channel MTP connector/ribbon cable assembly with 62.5/125 micron fiber, characterized for EO-1 environment.
- During vibration test one (1 min/axis): transients < .25 dB, post test optical loss < -.01dB.
- Thermal cycling: -.03 dB & -.16 dB (loss) @ -20 °C, post test average post test loss < -.50 dB.
- Post vibration test two (twice levels of test one for 3 minutes/axis) transients < .25 dB, average post test loss < -.10 dB,
- One fiber in 48 pistoned (cracked) as a result of testing.

- Pre thermal testing

- Post thermal testing

## Radiation Effects on Optical Fiber

- Total Ionizing Dose Effects
-   Operating Wavelength
-   Materials used as dopants
-   Fabrication procedure
-   Fiber Coating Materials
-   Temperature of Operation
-   Dose Rate
-   Total Dose

- Scintillation
- luminescence as a result of electron induced photons.

## Test IndexA:   Tested at energies 0.5 MeV and 1.0 MeVB:   Tested at energies 0.1 MeV, 0.5 MeV and 1.0 MeV*:   indicates fiber tested at 1.5 MeV

*Scan Index*
- 1. Indicates testing for a minute duration monitoring all   wavelengths simultaneously.
- 2. Indicates testing for a minute duration monitoring a single wavelength scan at 532 nm.
- 3. Indicates testing for a minute duration monitoring a single wavelength scan at 816 nm.
- 4.   Indicates testing over several minutes to capture data from a full scan of wavelengths from 185 nm to 900 nm.

- Electron Induced Scintillation Testing on Optical Fiber

## Optical Fiber Tested For Radiation Induced Scintillation

**Optical Fiber Tested For Radiation Induced Scintillation**

## Results of Electron Induced Scintillation Testing of Optical Fiber

- Events that occurred during testing were never over 250 photons/s, over the range 185 nm to 900 nm.
- Events that were recorded were attributed to arcing or discharging inside of the electron accelerator casing; from the stabilization corona points to the casing, and from the accelerator plates as a result of impurities in the beam line.
- Concluded that no radiation induced scintillation was occurring above the noise floor of the PMT at 50 photons/s since recorded events were not a result of radiation induced scintillation in the optical fiber but were events occurring inside the electron accelerator casing and causing RF spikes through the grounding of the equipment that was recording data in the room with the accelerator.

## Testing: Radiation Induced Attenuation of Spectran Hermetic Acrylate Rad Hard Fiber, BF0544, 0 to 215 Krads dose rate = 50 rads/min

## Total Ionizing Dose Radiation Induced Attenuation on Lucent SFT Flight guide and Commercial 100/140/172 Optical Fiber

## Total Dose Testing of Optical Fiber

- Spectran 100/140/500 Hermetic graded index optical fiber, Total dose testing at 25C and at two different dose rates.
- 50 rads/min, TID 100 Krads, Attenuation = 9.59 dB/Km
-   TID 15 Krads, Attenuation = 2.53 dB/Km
-   TID 150, Saturation @ 12.21 dB/Km
- 34 rads/min, TID 100 Krads, Attenuation = 6.45 dB/Km
-   TID 15 Krads, Attenuation = 1.69 dB/Km
-   TID 160, Saturation @ 9.18 dB/Km
- Testing of  Lucent SFT 100/140/172 Hermetic polyimide optical fiber, 100 m.
- 3 hrs @ 28.3 rads/min (5094 TID), 18 hours following 15 min rest at .34 rads/min with temperature steady at -125C during exposure.
- BF04436: 1st dose rate, optical loss ~ 3.82 dB,
-                  2nd dose rate loss ~ 4.7 dB and rising
- BF05202 (new process) : 1st dose rate, optical loss ~ 11.5 dB,
- 	 Flightguide               2nd dose rate loss ~ 7.3 dB and falling
- BF05202 (old process, SL PREM BASE): 1st dose rate, loss ~ 11.32 dB
-         Flightguide:                                         2nd dose rate, loss ~ 7.1 dB

## Conclusion

- Thermal Characterizations
- Length Shrinkage and Optical Stability:
- W.L. Gore (8388, FON1008, FON1004), 12 optical fiber ribbon cable with MTPs
- Spectran Flightguide,
- Northern Lights Hytrel Jacketed, MM and SM & RIFOCS H06, HL1
- Brand Rex OC1008, OC1614
- Vibration Characterization
- 12 fiber ribbon cable (W.L.Gore) and MTP (USCONEC)
- Radiation Characterization (Scintillation)
- Variety: Polymicro, 3M, Spectran, CeramOptec, Litespec
- Radiation Characterization (TID)
- Spectran: BF05444,
- Lucent SFT: BF05202, BF04436
- Outgassing: FON1008 passed with acrylate coated fiber

## IMAPS/NEPP Advanced Technology Workshop

- Session on Photonics/Optoelectronics
- May 24, 2000

- 8:05 am - 8:40 am
***Space Qualification of Optoelectronic and Photonic Devices***,   Dr. Quiesup Kim,  JPL
- 8:40 am - 9:15 am
***Kilowatt Peak Power Semiconductor Laser Arrays, The Challenge of Space Flight Qualification******,   ***Dr. Carl J. Magee, NASA Langley Research Center
- 9:20 am - 9:55 am
***Characterization of Commercial Optical Fiber Cables for Space Flight Environments at NASA Goddard Space Flight Center******,   ***Melanie Ott, Sigma Research and Engineering
- 9:55 am - 10:30 am
***Implementation of Optical Cables in a Spacecraft Environment******,  ***Doug Hardy, W.L. Gore
- 10:30 am - 10:55 am
***Defects in NFOC-2FFF-1GRP-1 Optical Cable Used in International Space Station Hardware******,  ***Jeannette Plante, Swales Aerospace
- 10:55 am - 11:30 am
***High Speed  InP Based 1 x 2 Optical Switch******,   ***Simarjeet Saini, University of Maryland