faheem freqstandardsinhollowfiber

8/9/2019 Faheem FreqStandardsInHollowFiber

1/40

Portable, robust optical

Frequency standards in hollow

optical fiber

Mohammad Faheem,

Rajesh Thapa, Ahmer Naweed,

Greg Johnson, and

Kristan Corwin


2/40

Motivation

Develop high accuracy Portable WavelengthStandards for Telecommunication

Industry.


3/40

Outline

roadening Me!hanisms and "aturation

"pe!tros!op#

$ntrodu!tion

Fre%uen!# measurement.

&'perimental "et(up

Results

Future )or*

+reious )or*

-imitations

Our Approa!h


4/40

Oer iew

C/0/

?

frequency

Fre%uen!# measurement Fre%uen!# !om1

-aser

23 Torr


5/40

"our!es

Coupler

Fi1er

4emultiple'er

Output Fi1ers

( Channel adjustment in )4M 562/2(6272 nm8 s#stem.

( Cali1ration o9 waelength measurement dei!es.

)aelength 4iision Multiple'

"eparation 1etween

!hannel is 6 nm


6/40

Re!ipe 9or a )aelength "tandard

Atomi! or mole!ular a1sorption lines

( A1solute 9re%uen!# re9eren!e.

( er# sta1le under !hanging enironmental

!onditions

( Good re9eren!es in the 6233 nm region

Good re9eren!es in 6233 nm region

»A!et#lene 56263(62:3 nm8

» 0#drogen !#anide 562;3(6272 nm8

» Ru1idium 56273(62


7/40

A!et#lene 5 Also !alled &th#ne8

0 C C 0

( Colorless and e'tremel# 9lamma1le- 23 transition lines, spa!ed 1# 73(=3 G0> e'tending 9rom

6262nm(62:3 nm

Anti(s#mmetri! C( 0 1ond "tret!hing

C C0 0

"tret!hing i1rations

C0

CC

C0

ν6

ν/

"#mmetri! C( 0 1ond "tret!hing

ν;

ν6?ν; lies in 6.2 m region


8/40

4oppler roadening

m

kT

c

wo Doppler 2ln2

2=δ

$mportant roadening $n $R "pe!tros!op#

A1sorption sample

$O $

>

z w

oe I I )(α −=

@ @is the a1sorption !o99i!ient

22

2

)2/()(2/

4 γ π γ

ε α

+−

=

wwmc

Ne

oo

A1sorption 5eers law8

+ower roadening

s

power

P

P S

S

=

+= 1γ δ

Laser spectroscopy by Wolfgang Demtroder

C/0/ at room temp. B 233 M0> .max2~ power δ

3 233 6333 6233 /333

(;

(/

(6

3

A r 1 i t r a r # A ' i s

Fre%uen!# in M0>


9/40

$mportant 1roadening near $R spe!tros!op#

+ressure 1roadening

and shi9t

∫ ∞

−=+=∆0

))(cos1(2 RdR Rwherev N wbb η σ σ γ

-ine "hi9t

RdR Rwherev N s sessure ))((sin0

Pr η σ σ δ ∫ ∞

==

Transit(Time roadening

)2ln(2)/(4 d vtt =δ

Transit time TdD

Laser spectroscopy by Wolfgang Demtroder

C/0/ 1roadening +5638 B 66.7 M0>DTorr

-ine roadening

C/0/ line shi9t +5638 B 3./< M0>DTorr

233 K0> 9or 3.


10/40

"aturation "pe!tros!op#

• &liminates 4oppler width• Re%uires high +ower 5T#pi!all# ;33 m)

9or a!et#lene8

• 4ominant -ine width

+ressure 1roadening 5B66 M0>DTorr 8Transit(time 1roadening 5!oheren!e

time 1etween laser and mole!ules8+ower roadening

• "ignal "i>e

4epends linearl# on pressure4epends linearl# on sample length

M6M/

- a s e r

Cell

."

4et.

+ump eam +ro1e eam

63E


11/40

Fre%uen!# Measurement

Fre%uen!# C#!lesDse!ond

4e9inition o9 time Caesium 6;; atom

Opti!al 9re%uen!# ((((( $n hundreds o9 T0>

$ts eas# to measure in T0>

+hoto 4ete!tor (((((( $n :3(633 G0>

)hat we need to do

Mode -o!*ing Fre%uen!# Com1

4uration o9 < 6


12/40

Time(Fre%uen!# Corresponden!e

2∆φ

τr .t = 1/f r

t

E(t) ∆φ

0 9 n n 9 r ? 9 o

I (f )

f

9 r

9 o

fr Laser repetition rate

fo Offset D. J. Jones, et al. Science 288, 63 !2""" )

Fourier transform of periodic signal discrete frequency components.


13/40

Measurement o9 9 r and 9 o

9 r !an 1e measured with photo(dete!tor in opti!al path

Repetition Rate

O99set

0 9 /n

I (f )

f

9 n

9 r

9 o

/9 n(9 /n /5n9 rep?9 o8 ( 5/n9 rep?9 o8 9 3

O!tae "panning

( Mi!rostru!ture 9i1er

( -aser Cait#

D. J. Jones, et al. Science 288, 63 !2""" )


14/40

A.C>aj*ows*i,J.& ernard,A.A.Madej,R.".)inler

"el9 re9eren!e 9re%uen!# !om1

f

Hn*nown signal

#pp.Phys.$%&,'(2" !2""')

Hn*nown signal

9 o

9 r


15/40

"olid !ore mi!rostru!ture Fi1er

Fused silica core

1.7 m

(=3

(G3

(73

(23

(:3

(;3

(/3

6/336333=33733:33

laser

spe!trum

633 m)

56 nJ8

"pe!trum roadening

/3 m)

53./ nJ8

)aelength 5nm8

R e l a t i , e + o w e r 5 d 1 8

CladdingCore


16/40

Fre%uen!# !om1 "et(up

Fiber in Fiber outFiber Laser

10 W

1075 nm

HNLF

! "!r#forsterite Laser

$%

nonlinearcrystal

stabili&ed optical

frequency comb

ynt'esi&er

frep Loop

Filter

('ase

$etector

ynt'esi&er

f0 Loop

Filter


17/40

Pre*ious wor+ -.a+a/awa, 0.de 1abachelerie, .#waiand -ouro/i

!J.opt.soc.#4.$5ol.73,o.725Dece4ber7&&6)

- -ong intera!tion length.

- 0igh intra!ait# power 5633 mw8.

- Fragile.- Cait# and laser lo!*ed to

resonan!e independentl#.

Cait# I

"ignal Measurement I

- Two photon R1 5= nm8 transition as

a re9eren!e.

- 0#drogen C#anide56227 nm, +5/88 as a

$ntermediate re9eren!e.


18/40

Pressure broadening & shiftFor P(1! broadening 66.: M0>DTorr "ine shift 3./ M0>DTorr #$ect of Temp negligible e$ect%sed to calibrate ptical Spectrum

'nalyers (S')s!

Pre*ious or+ .9. Swann and S.1. :ilbert. !;S


19/40

Saturation signal * 1 +,+easure Po-er shift 11./ ,0m-Pressure Shift 2 0>DmTorr

Pre*ious or+ I #.9>a+ows+i, #.#.0ade, P.DubeDe*elop4ent and Study of a 7. u4 ?ptical frequency Standard referenced to p!76) Saturated

absorption line in the !7@*3) o*ertone band of 739 2 A 2

Opti!s Communi!ations /;:5/33:8 /2


20/40

4eelop high a!!ura!# porta1le waelength "tandards 9or

tele!ommuni!ation industr#.

Our Approa!h

( Cait# 1ased re9eren!es are not +orta1le.

( Transitions in the glass !ells !an not 1e 9urther

narrowed. "olution I

Hse mole!ular a1sorption inside opti!al 9i1er.

AdantagesI

- +orta1le- &as# to align- &asier to get high intensities oer long path

Through e'isting Te!hnolog# I


21/40

&'perimental "et(up

Capa!itie

manometers

0ollow opti!al 9i1er

Gas $nlet Gas $nlet

6 m)

To a!uum pump

+ro1e +ump

562 ( ;338 m)

C/0/ mole!ules

Fiber in Fiber out

ultimately3

" O i


22/40

"etup( Opti!s

4iode

-aser

$"O

"%uee>er

+"

"%uee>er

+"

Fi1er

63D


23/40

Capillar# Tu1e

Too loss#

3

2

/1a

l atten

λ α

-ength 6= !m and dia ;;3 m

-aser

+ower loss

/a

l

Onl# :3E transmission

4oppler roadened signalo1sered

No saturation signal;33 733


24/40

Capillar# tu1e

3 63 /3 ;3 :3 23 73

23

73

G3

=3


25/40

+hotoni! andgap 9i1er

12 m

loss4 2.2 d50m

No total internal re9le!tion

raggs re9le!tion


26/40

63(m +hotoni! andgap 9i1er

(6233(6333 (233 3 233 6333 6233

(/./(/.3

(6.=(6.7(6.:(6./(6.3

(3.=(3.7(3.:(3./

3.3

T r a n s m i s s i o n 5 a . u 8

Fre%uen!# 5M0>8

At 63 m)

+ump L +ro1e

+ro1e

Re9le!tion o9 +ump

1eam 9rom 9i1er ends

"aturation 4ip


27/40


(6333 (233 3 233 6333

3.3

3./

3.:

3.7

3.=

6.3 66/ m) 5? 3.:8 =; m) 5? 3.;8

:3 m) 5? 3./8

/3 m) 5? 3.68

63 m)

F r a ! t i o n

a l A 1 s o r p t i o n

Fre%uen!# 5M0>8

(:33 (/33 3 /33 :33 733 =33(3.7

(3.2

(3.:

(3.;

(3./

(3.6

3.3

66/ m) 5( 3./8

=; m) 5( 3.68

:3 m) 5( 3.68

/3 m) 5( 3.328

63 m)

F r a ! t i o n a l A 1 s o r p t i o n

Fre%uen!# 5M0>8

"igni9i!ant signal strength at 63

and /3 m) pump powers

7.2


28/40

)e are transit limited or pressure limited


733 =33 6333 6/33;2

:3

:2

23

22

73 )aelength 62;6.;6 nm

- i n e w i d t h i n M 0

>

+ressure in mTorr

N

v N

P

s pressure

α δ

σ δ = -ine width does not in!rease signi9i!antl# with pressure whi!h implies

that it is transit time limit.


29/40

6333 /333 ;333 :333

-(

-%

"

+ump?+ro1e

+ro1e onl#

Mi!helsonNs 9ringes

A r 1 i t r

a r # H n i t

Fre%uen!# 5M0>8

/3(m +hotoni! andgap 9i1er

3 /3 :3 73 =3 6333.3

3./

3.:

3.7

3.=

6.3

F r a ! t . T r a n s m i s s

i o n

Time 5s8

2 m core6 72 cm lengthFiber 8lls to mTorr in * 12 s

2 9m6 : cm long P5F at 1;1.2 nm

6733 6=33 /333 //333.63

3.62

3./3

3./2

3.;3

3.;2

3.:3

3.:2

F)0M /

A r 1 i t r a r # u n i t s

Fre%uen!# in M0>


30/40

/33 :33 733 =33 6333

//

/:

/7

/=

;3

;//3 m FF

- i n e ) i d t h 5 M 0 > 8

+ressure 5mTorr8

/3(m +hotoni! andgap 9i1er

+ressure limited

Transit limited

Fa!tor o9 ; !hange in pressure gies a 9a!tor o9

6./ !hange in line width


31/40

/33 :33 733 =33 6333 6/33/3

/2

;3

;2

:3

:2

23

22

73

63 m +F

/3 m +F

- i n e w i d t h i n M 0 >

+ressure in mTorr

)2ln(2)/(4 d vtt =δ

63(m, /3( m +F data Comparison

To redu!e Transit time roadeningI

in!rease 9i1er hole si>e(or( 9ind a heaier mole!ule

(or( 4e!rease the elo!it# o9 mole!ule 1#

!ooling

Transit Time


32/40

"ignal strengthI

• optimal 9i1er length 9or pressure

Noise

• $nter9eren!e 5pro1e with stra#Dre9le!ted pump8

• laser intensit# noise

-inewidthI 5target 6 M0>8

• transit time 1roadening

• pressure(1roadeningTo narrow the transition, we mustI

» redu!e transit(time 1roadening» redu!e the pressure

» lengthen the 9i1er

Hltimate limits


33/40

( O1sered saturated a1sorption 9eatures in photoni!

1andgap 9i1er 9or 9irst time.

( "igni9i!ant a1sorption 9ra!tion o1sered at lowpower 5 /3 m)8, with /; M0>(wide 9eature.

( Con9irmed transit time 1roadened, /3 m produ!e

narrower 9eature than 63 m 9i1ers

Con!lusions


34/40

Future +lan

Near(termI Ma*e more porta1le, redu!e noise.uild 9re%uen!# Com1 9or a1solute measurement.O1sere dependen!e o9 di99erent 1roadening

me!hanisms.O1sere the shi9ts in +hotoni! 1andgap 9i1ers.

-onger(termI "eal the 9i1er 9illed with gas. 5Greg Johnson8

Narrow the transition&'plore larger photoni! 1andgap 9i1ers&'plore other gases.


35/40

Than* Pou


36/40


37/40

+hotoni! andgap 9i1ers

$nde'

guiding

0ollow Core guiding


38/40

"aturated a1sorption 9eature width

(6333 (233 3 233 6333(3.63

(3.3=

(3.37

(3.3:

(3.3/

3.33

3.3/

1" mW

%" mW

F r a ! t i o n a l A 1 s o r p t i o n

Fre%uen!# 5M0>8

12 m

Transit time 1roadeningI Naieestimate

t dD B6D23 M0>

+ressure 1roadeningI

66 M0>DTorr Q 6./ Torr 6;./ M0>

* /2 +,


39/40


40/40

$mportant roadening $n $R "pe!tros!op#

4oppler roadeningMole!ules are in motion when the# a1sor1energ#. This !auses a !hange in

the 9re%uen!# o9 the in!oming radiation.

+ressure 1roadening

+rodu!e 1# the shi9ts o9 energ# leels 1#intera!tion o9 radiating atom with near 1#

parti!les

Transit time roadeningThe intera!tion time o9 mole!ules with the

radiation 9ield is small with thespontaneous li9e time o9 e'!ited leels

+ower roadeningMole!ules a1sor1 energ# 9rom intense laser.

This !auses a energ# shi9t !ausing 1roadening.

faheem freqstandardsinhollowfiber

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