# Presentation: 866545

## Characterization of Integrated Fiber Optical Modulators for Space Flight 

***Sigma Research and Engineering / NASA Goddard Space Flight Center***
***Component Technologies and Radiation Effects Branch***
- _[Melanie.](mailto:Melanie.ott@gsfc.nasa.gov)__[ott](mailto:Melanie.ott@gsfc.nasa.gov)__[@](mailto:Melanie.ott@gsfc.nasa.gov)__[gsfc](mailto:Melanie.ott@gsfc.nasa.gov)__[.](mailto:Melanie.ott@gsfc.nasa.gov)__[nasa](mailto:Melanie.ott@gsfc.nasa.gov)__[.](mailto:Melanie.ott@gsfc.nasa.gov)__[gov](mailto:Melanie.ott@gsfc.nasa.gov)_
***301-286-0127***
***URL:  http://misspiggy.gsfc.nasa.gov/tva/authored/fo_photonics.htm***

***Characterization of Integrated Fiber Optical Modulators for Space Flight ***

- The Team:
***Dr. Carl Magee, Juan Vela, Harry Shaw, Patricia Friedberg, Matthew Dodson***

- NEPP Workshop 2002: Optical Fiber Modulators for Space Flight

## Outline

- Objectives
- Approach
- Failure modes
- Failure modes vs. testing
- Telecordia standards
- Modulator characterization parameters
- Typical test for aging
- Innovative test method for failure modes and characterization.
- Criteria for modulators in survey
- Survey of modulators
- Summary
- Planned work

- NEPP Workshop 2002: Optical Fiber Modulators for Space Flight

## Objectives

- To enable the usage of commerical off the shelf optical fiber modulator technology for space flight use.
- To develop innovative test methods to make the path to usage quicker and less expensive.
- To provide information on test plans, methods, and candidates that are appropriate for typical environments.

- NEPP Workshop 2002: Optical Fiber Modulators for Space Flight

## Approach 

- Failure modes study.
- Standards and tests identification.
- Evaluation of testing plans.
- Identify innovative test methods.
- Survey for candidates based on failure modes and space flight requirements.
- Validate best candidates through innovative test plan.

- NEPP Workshop 2002: Optical Fiber Modulators for Space Flight

## Failure and Degradation Modes

| Failure/degradation mode | Description |
| --- | --- |
| DC Drift | Bias ready devices, drift to maintain quadrature, results in higher BER. |
| Fiber Buckling (break) | Materials shrinkage and aging can exacerbate, can be mitigated through packaging design. |
| Hydrogen Diffusion  | Proton diffused devices only, as a result of aging. |
| Material Expansion Mismatching | Thermal changes can cause stresses as a result. |
| Degradation of Coupling Material | Launching excessive power into device.  |

*200mj/cm**2** damaged *
*the coupling material.*

- NEPP Workshop 2002: Optical Fiber Modulators for Space Flight

## Failure Modes

| Failure/degradation mode | Corresponding Test |
| --- | --- |
| DC Drift | Elevated temperature |
| Fiber Buckling (break) | Thermal cycling, Vibration |
| Hydrogen Diffusion  | Elevated temperature test |
| Material Expansion Mismatching | Thermal cycling |
| Degradation of Coupling Material | Increased optical power |

- NEPP Workshop 2002: Optical Fiber Modulators for Space Flight

## Telecordia Tests

| Test | Quality Function |
| --- | --- |
|   Drop Shock | Wirebond quality. |
|   Vibration | Mechanical resonance, flaws in subcomponents. |
|   Thermal Shock (hermetic) | Hermetic seal, fiber breakage. |
|   Solderability | Mechanical integrity. |
|   Fiber Pull | Fiber breakage, hermetic package. |
|   Accelerated Aging (high temp) | Overall long term reliability, Vdc drift. |
|   High Temp Storage | If aging is performed at this temp, it is redundant. |
|   Low Temp Storage | Not usually performed unless requested. |
|   Thermal Cycling  | All aspects of the packaging design, materials, seal etc. |
|   Damp Heat | Not performed on hermetic unless exposed epoxy. |
|   ESD Threshold | Electrodes. |
|   Internal Moisture (hermetic) | Hermetic packaging. |
|    |  |

- X cut devices do not require hermetic packages

- NEPP Workshop 2002: Optical Fiber Modulators for Space Flight

## Characterization Parameters

- S11, VSWR
- S21, Frequency response
- Vrf
- Vdc
- Phase, shift away from quadrature,
- non bias devices
- Optical Loss, insertion loss
- Return Loss, Pin/Preflected
- Extinction Ratio, Opticalmax/Opticalmin

- More efficient method of characterizing the functionality and predicting performance; system approach, by monitoring BER and optical insertion loss.

- NEPP Workshop 2002: Optical Fiber Modulators for Space Flight

## 2000 to 10,000 hours.
> 70°C usually 85°C or 100°C.  The higher the temp, the larger the Vdc swing.
Maximum modulation rate.
Titanium waveguides (bias devices: X or Z cut), two tests required, 
constant quadrature, monitor Vdc/Vi, insertion loss, BER
constant voltage, monitor phase, insertion loss, BER.
Proton waveguides (no bias, X cut), 
monitor BER, phase, insertion loss

- > 70°C usually 85°C or 100°C.  The higher the temp, the larger the Vdc swing.
- Maximum modulation rate.
- Titanium waveguides (bias devices: X or Z cut), two tests required,
- constant quadrature, monitor Vdc/Vi, insertion loss, BER
- constant voltage, monitor phase, insertion loss, BER.
- Proton waveguides (no bias, X cut),
- monitor BER, phase, insertion loss

*Typical Reliability Test*

- Accelerated aging at high temperature

- System Approach

- NEPP Workshop 2002: Optical Fiber Modulators for Space Flight

## Innovative Test Methods

- Thermal cycling for aging and to bring out a majority of failure modes,
- To device specifications,  example -45°C to +85°C.
- Long soak of 40 min at extremes 1°C/min ramp rate.
- Not less than 100 cycles.
- Monitor pseudo random binary sequence (PRBS) extinction ratio “eye pattern” instead of the BER. Integrates intrinsic parameters in to one extrinsic parameter.  (NIST method for 2.5 Gb/s devices).
- Monitor insertion loss.
- To stress RF electrodes, can use RF sine wave at specified frequency and voltage.

- NEPP Workshop 2002: Optical Fiber Modulators for Space Flight

## Criteria for Survey

- 10 Gb/s devices,
- that can operate at 1 Gb/s.
- Telecordia qualified.
- Mitigated failure modes.
- Low power requirements.
- Low insertion loss.
- High extinction ratio.
- Large input power limit.
- Wide optical bandwidth

- NEPP Workshop 2002: Optical Fiber Modulators for Space Flight

## Survey Summary

| Codeon Corp **
part # 10GXBO-S-S  | 0 V  | < 5.5 V  | 50 mW  | 1525-1605 nm
 | > 20 dB  | < 5.0 dB  | -40 dB |
| --- | --- | --- | --- | --- | --- | --- | --- |
| JDS Uniphase **
part # 21012957  | < 8.0 V  | < 6.8V  | 50mW  | 1525-1565 nm  | > 20 dB  | < 5.0 dB  | -45 dB |
| Agere Systems **
part # 2623CSA  | < 4.0 V  | < 5.0V  | 30 mW  | 1525-1620 nm | > 27 dB  | < 5.5 dB  | -35 dB |
| Micro Photonix  | < 6.0 V  | < 5.5V  | 50mW  | 1510-1590 nm | > 15 dB  | < 5.0 dB  | -50 dB  |
| Srico Inc.
part # 400-03-C  | < 5.0 V  | 15.0V  | 30 mW  | 1550 nm | > 20 dB  | NA |  NA |
| EOSpace  | < 4.5 V | < 10.0V  | NA | 1550 nm | > 13 dB  | < 3.0 dB  | -45 dB  |
| Aeroflex Trilink
M10P  | < 6.0 V | < 7.0 V  | NA | 1520- 1580 nm | > 20 dB  | < 4.5 dB  |  -45 dB  |

- Vπ

- Device

**V****RF**** **

**Optical**
**Power**

- 

**Extinction Ratio**

**Insertion Loss**

**Return Loss**

- NEPP Workshop 2002: Optical Fiber Modulators for Space Flight

## Environmental Test Plan

- Materials analysis and test,
- System analysis and test
- Vibration testing,
-  Random vibration to protoflight levels,
- Verify survival during launch using typical launch parameters ~ 14.1 grms total for protoflight small box components.
- 3 minutes per axis, 20 grms total
- Thermal cycling aging,
-  long dwell at extremes, 1 °C/min to extent of specification, -45°C to +85 °C for 100 cycles, 40 minute soak. Monitor insitu “eye pattern” and insertion loss. Stress RF electrodes.
- Radiation analysis and test.
- Space flight environments from GSFC are less than 1 rad/min and more typically less than .1.

- NEPP Workshop 2002: Optical Fiber Modulators for Space Flight

## Summary

- System approach
- Method to mitigate failure modes, design choice
- X cut devices do not require hermetic packaging.
- Still needs to be verified.
- Proton waveguides, no bias requirement, drift reduction.
- Proposed method to test for reliability and for failure modes using “eye pattern”.

- NEPP Workshop 2002: Optical Fiber Modulators for Space Flight

## Space flight requirements.
Formulate space flight test plan.
Additional tests.
Sample size.
Lower data rate, then higher data rate.
Testing using innovative methods.
Document all information.

- Formulate space flight test plan.
- Additional tests.
- Sample size.
- Lower data rate, then higher data rate.
- Testing using innovative methods.
- Document all information.

*Planned Work*

- http://misspiggy.gsfc.nasa.gov/tva/authored/fo_photonics.htm
- http://www.nepp.nasa.gov/

- This work is funded by NEPP Parts Program

- NEPP Workshop 2002: Optical Fiber Modulators for Space Flight