Ongoing qualification activities of LiNbO3 modulators. Passive (unpumped) radiation testing of Er-, Yb-, and Er/Yb-doped fibers: a) Yb-doped fibers exhibit higher radiation resistance than Er-doped fibers; b) Er/Yb co-doped fibers exhibit largest radiation resistance. Active (pumped) radiation testing of Yb-doped fibers conducted at NASA GSFC: a) Typical decay behavior observed; b) No comparison could be made to other fibers due to problems with test setup. Development of new high power fiber terminations

Chuska, Rick

LaRocca, Frank

Ott, Melanie

Switzer, Rob

Thomes, Joe

NASA Technical Reports Server

?emote a~llsing & high-bandh~utn ~ornmuni?~ 
- Physical sensing (altimetry, ranging, 3D LIDAR) 
- Chemical sensing 
nvestigation of fiber laser systems and ' 
:omponents to raise / evaluate technology 
readiness level (TRL) 
- Confidence for future mission 
art of NASA Electronic Parts and Paokaaina (NEPPf 
@:llne~a.nasa.ao.' 
r laser focus a1 ; 
- Source I transmitter 
""adulation 
* Fiber Lase 
Qualification 
( Lithium Niobate Modulator $W5 
* Passive (unpumped) Fiber Radiation ~nct in#t ' i  
Active (pumped) Fiber Radiation Te! $'@ 
* High Power Fiber Te 
* Conclusio~ 
(COTS) components when possible 
lleviate tight budget and schedule 
- Often requires custom packaging 
uptical component qualification 
1; - Initial gamma radiation screenir- 
9 Transmission loss and annealing 
- Thermal vacuum testing 
-xtended radiation testing 
https://ntrs.nasa.gov/search.jsp?R=20090006875 2019-08-30T06:05:49+00:00Z
High extinction ratio intensity modulator 
Manufacturer: Photline Technologies 
Proton exchange waveguides 
Separate DC and RF biasing 
LiNbO, X-cut Y-propagating 
PM input and output fibers 
Input - - Modulated 
Waveform Out I 
Separate biasing of DC and RF portions of waveguldlng region 
Modulated s~gnal's DC level w~l i  dr~ft durlng normal operation 
::*.; ..\ - I - .  $ -: 
I .- 
. , , . ,  
--,v, 
Picked DC bias voltage for quadrature operation 
lo allow for maximum change without clipping 
I I 
Dr~ft in DC output level 
in peak-to-peak output 
I . . . . . .  
0 r n . m I m I m , o l l a D I  
- I  
Gnnzm Rnrlinfion Results 
- -  
7.2 radlmin 52 krad total dose 
'osl-radtatlan testlng to examlne Induced 
:hanges m modulator operation 
I 
-1esircrble Prouerties 
of Fiber Lnser~ 
High efficiency 
- Low power consumption, low waste-heat 
generation 
- Up to 40% electrical-to-optical conversion with a 
Yb-doped fiber amplifier has been demonstrated 
Diffraction limited beam quality 
- Minimum divergence, smallest spot size 
- Reduced speckle 
High reliability through mo ,~ljthj,q structure 
- Fiber-coupled componentsfi#id 
- Sealed, alignment-free optical system 
Gsirnble Properties o f  Er-Doper1 
m d  ErNb Co-Domd Fibers, 
Er-doped fibers 
- Amplification in the range of 1.5 ym 
sed for communication systems 
- Yb acts assensitizer and absorbs light, 
transferring energy to the Er atom, from where 
light is re-radiated at communication wavelengths. 
- This process leads to a larger overall absorption 
per unit length, i.e. shorter amplifiers. 
Structure of Yb-atom 
- Simple energy band structure minimizes excited 
state absorption 
- Low quantum defect 
- No or little concentration quenching 
- Long upper-state lifetime 
High-power applioations possible 
- High Yb-doping concentrations possible 
- Double-clad fibers can improve power capabilities 
Fiber Laser Testiizp 
lhr/~rnttperl Cn~rfg~rrrrliair 
Ongoing collaborative research on radiation-induced 
effects in Er-, Yb-, and ErNb-doped fibers 
Initial testing focused on unpumped (passive) fiber 
configurations 
Testing conducted at Sandia National Labs' Gamma 
Irradiation Facility (GIF) 
- 
Sandia 
National 
Laboratorie: 
Sh~elded gamma cell Test f~bers located In gamma test chambe1 
for rad~atlon exposure the d~stance from 
the source determlnlng the dose rate 
source 
Broadband optical radlat~on from xenon ar 
lamp located outs~de the test chamber 1s 
coupled Into a set of standard S10, dellver 
f~bers 
set PZ Dellvery f~bers enter test chamber through 
access ports and couple l~ght Into the test 
Dellvery fibers - f~bers located lns~de the gamma test 
chamber 
output to 
dSpectro- Transm~ss~on spectrum of each test f~ber 
meter 
monitored at 1 mln Intervals throughout - 
l~maling hour gamma exposure 
C." 4 
, , ,: 'f 
Representative data show the 
effect of accumulated doses of 
gamma radiation on the 
normallzed optlcal transmittance 
of a Yb1200-41125 f~ber 
Wavelength dependence of 
radlat~on-lnduced opt~cal losses 
v~s~b le  at large total doses 
Dose rate = 40.1 rad(Si)ls 
Fiber Lrlser Testiltg I 
Flbsr Samples 
Yb1200-201400DC, Yb1200-301250DCCYb12QO- 
41125, Yb1200-10/125DC, Yb2000.61125DC 
Er16-81125, ERO-41125, Er30-41125, Er40-125. 
ErBO-41125, Er110-41125 
grlY b co- OFS ErIYb PM DC 
do~ed Abet 
Note: First number designates the nominal peak absorption in dBlm 
at 476 nm for Yb (1630 nm for Er), and the second and third 
numbers denote the core and cladding diameters respectively in 
Vrn. The 'DO' designates the double-clad fibers. 
Plglalls (SMF-28, HI-1060) were utl l~rad to couple reference 
xenon llght into the core of double-clad Yb-doped flbers 
Representat~va data show the 
effect of accumulated doses of 
gamma rad~allon on the 
normalized o tical transmittance 
of ai l  E R O - ~ R ~ ~  fiber 
II Wavelen th dependence of 
radiation%duged optical losses 
visible at large total doses 
8 Absolplion festure at 1500 nm. 
I R~plgspntatlve data show the 
effect of accumulated doses of 
gamma radiation on the 
normallzed opt~cal transmltlance 
of an OFS ErIYb PM DC flber I 
Wavelenglh dependence of 
radlalton-tnduced optical losses 
vlslble at large total doses 
Pholodarkenlng proceeds 
slowly I 
Absorptton fealure at 1500 nm 
due to E-" 7 I 
Dose rate = 40.1 r~d(8i)ls 
. Optical transmittance 
measurements for 
Yb1200-41125 fibers 
exposed to two distinct 
dose rates. 
Up to a 10% increase 
(relative change) 
observed in measured 
optical transmittance loss 
at higher dose rate. 
Rrrrlicrtion-I~t(lucwd Loss With Qose 1 
I . Dew * ~ t i o a l  transmittance for 
Ere Sb- and FrlYb-cloped f~bers 
st i100'nm 
I Rad~at~~n-lndgced o t cal 
transm~ttance reducfcn Is roughly 
exponent~al in nature for all flbers 
8 Yb-doped fibers (2.5) are more 
rsd~al~on raststanl than Er-doped 
f~bers (6-1 0) 
8 Qn.d~pedfiber6 (I) exhib~l the 
most rad~atlen reels anoe wlth~n 
he eulte Q+ tested fibers 
Dose rate = 40.1 rad(Si)ls 
-8 . . r 
Dose Rate Effects !or BET-Doped Fiber I 
-4 Optical transrn~ttance 
measurements for Er20- 
41125 f~bers exposed to 
three dtstlnct dose rates. I 
I Dose rate dependence 
observed, which 
increases with larger total 
dose. I 
I Increase of 
photodarkenlng (relattve 
change) due to higher 
dose rate 1s under 10%. I 
Passive tests showed that Yb-doped fibers 
exh~blted higher radiation resistance than Er- 
- lnltlal active testlng will focus on Yb-doped flbers 
lnitlal actwe (pumped) configuration tests were 
conducted at NASA GSFC 
- Study self-annealing effects due to pumplng durlng 
radlatlon exposure 
- Testlng and results prov~ded by Tracee Jamlson- 
Fiber Laser Testittg 
I P I I I I I ~ C ~ I  Co~ijigt~r(ltion 
Chsncteristirs dDiode LasersandGain Fibers 
I 
mmd Gom Ulooulpur ol2Sm Icsd- 
Fiber Lnsev Testing 
Atntped Coirjig~r~~tios 
I 
Nufern LMAYDF-lY130 FIBER 
1.20E06 
1.WE06 
8.WE07 
t 2 6.WE-07 
2 4.WE-07 
%.WE07 
O.WE+W 
0 M03 4WO 6MX) m 1 m  12M)J 
5x0 
Data provided by Tracee Jamlson-Hooks I 
Fiber Laser Testi~ 
P W ~  r ~ ~ n g t t m a ,  #?:&:*I# 4,:' . , b c 
I Data prov~ded by Tracee Jarn~son-Hooks 
High Power Fiber Tmincrtiott,- 
I Mechanical polishing techniques developed for 
handling high power without endface damage 
- Limited by silica I air interface breakdown 
- Being used in high power fiber laser applications 
I New ferrule designs for high power injection 
- Allow slight mechanical misalignment without 
catastrophic damage 
W Fiber Laser Tgs- 1 ;%TON&! 
LElKl FIBER 
Data prov~ded by Traoee Jarn~sorl-Hooks 
* Ongolng qualification activities of LiNbO, modulators 
Passive (unpumped) radiation testing of Er-, Yb-, 
and ErIYb-doped fibers 
- Yb-doped fibers exhibit higher rad~ation resistance than Er- 
doped ftbers 
- Er/Yb co-doped fibers exhibit largest rad~ation resistance 
Active (pumped) radiation testing of Yb-doped fibers 
conducted at NASA GSFC 
- Typ~cal decay behavlor 0 b s e ~ e d  
- No comparison could be made to other flbers due to 
problems with test setup 
Development of new high power fiber terminations 
,orators af Unrverslly of Arizona an Sandla Nsllona 
paJslve testng of\bers 
Spee~al thanks lo NASA Radlatlon Effepts Group" 
$FC Testing was performed st NASA GSFC 
~oaled in Code S61 Greenbelt MD snd F nd 
Eledtonlc Parts and ~ackagin~%lo~ram 


Fiber Amplifier Report for NEPP 2008

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