1. in non-hermetic 85/85 condition
Ageing of VCSELs
in non-hermetic 85/85 condition
S. Hou, 2014/09/18
Academia Sinica

2. Sample preparation VCSELs of various manufacturers
die/wire bonds by FOCI
TOSAs
TrueLight 10 Gbps on PCB

3. DC light power measurements
V-I-L scan by a LabView setup
VCSELs covered by a large (10×10 mm2) GaAs PIN, Mechanical alignment is required
NI 6024E PCMCIA to an XP notebook
Power meter measurement

4. DC bias to VCSELS DC bias by Agilent E3631A, Keithley 2304A
current kept at ~ 5 mA/ch
Bias at 1.65 V, 1.75 V, 2.0 V, to VCSELs
channel current measured, bundled.

5. 85/85 chamber Temperature stable ~ 0.1 oC Humidity stable ~ 0.2% RH
Cooled to 30/55 before opening, to prevent condensation
Burn periods conducted
30/50 : 118 hrs
85/85 : 12 hrs
85/85 : 94 hrs
85/85 : 275 hrs
85/85 : 316 hrs
85/85 : 363 hrs
85/85 : 534 hrs

6. Reference samples 1F45 1F58 1F58 1F59 1F59 Spare from 85/85 test,
to examine systematics in DAQ
TOSA of Truelight, 3 types
1F45
4.25 Gbps
1F58
10 Gbps
1F58
1F59
10 Gbps
1F59

7. Reference samples FINISAR 2092-001 5 Gbps a board has two 4x1 arrays
VCSELs are not centered at PIN
 light collection deviates

8. TOSA in 85/85 tests 1F58 1F45 1F59 1F45 A board with12 TOSA
of Truelight
1F Gb
1F Gb
1F Gb
No obvious loss
after ~1200 hr
biased in 85/85
1F58
1F45
1F59
1F45

9. Bare-die VCSLEs of FOCI Lightpeak in 85/85
One board having 10 VCSELs of Lightpeak (A-brand)
Biased in 85/85 for 1600 hrs
Minor degradation within systematic uncertainties
L-I shapes differ due to angle to PIN photo detector
ch closer to PIN center near PIN edge

10. FINISAR 4x1 arrays in 85/85 V850-2902-001, 5 Gbps 1600 hrs in 85/85
One board, two arrays,
total 8 channels
One channel showing large degradation, reason not clear
others are consistent with small degradation

11. Oxide-confined VCSELs, degradation in 85/85
Three types of Truelight, not expected hermetic
TSD-000, 2.5 Gbps, 10 lost 6, after ~400 hrs
TSD-008, Gbps, 10 lost 4, after ~1100 hrs
TSD-051, 10 Gbps, lost 2, after ~1100 hrs
Degradation in ligth level,
then sudden loss of light, drawing current still
ch closer to PIN center near PIN edge
Not sure what cause degradation,,
For channels near PIN center
PIN geometrical matters
Not observed in other brands
TSD-051

12. Summary Environment tests conducted to VCSELs
85 oC, 85% RH, up to 1600 hrs
TOSAs having VCSELs sealed is show negligible degradation
Bare Die VCSELs of LightPeak A-brand, Finisar array
show negligible degradation
Degradation of Oxide-confined VCSELS
followed by sudden loss of light
Two brands of VCSELS supposed for non-hermetic Chip-on-board
Failed in room condition within a week
 collaborate with the manufacturer to find the cause
1. compare sealed samples with open ones  humidity damage
2. use current source power supply  surge in voltage power supply
3. checking on signs of ESD damage