Transcript Diapositiva 1 - ego

T2
INFN-LENS
Braginsky et al., Phys. Lett. A 264, 1 (1999)
2 (1   )
1
S () 
S
(  C r )

2
2
xx
abs
2
2
o
Cerdonio et al., Phys. Rev. D 63, 082003 (2001)
2 (1   )
S () 
S K  
(  )
2
2
xx
 
abs
2
1
c

Cr


0

2
o
2
u 2 / 2
ue
K ()    du  dv

(u  v )(u  v  i)
2
2
2
2
2
1
0
-1
log( K() )
Photon absorption

Local heating

Thermal expansion
-2
-3
-4
-5
-6
-3
-2
-1
0
1
2
3
log()
STREGA kick-off meeting, Cascina 12 May 2004
INFN-LENS
T2
De Rosa et al., PRL 89, 237402 (2002)
10
-12
10
-13
10
-14
10
-15
Power modulation, P=Po + Pm sin ωmt
l (m)
Phase-sensitive detection
C2
C1
D3
D2
OI
P
EOM1
10
-2
10
-1
10
0
10
1
10
2
10
3
Fitting curve: l = Lo K(/c)½
FM locking
Laser
-3
m (Hz)
BS
HW
10
P
D1
EOM2
BS
lock-in
c = 2.8 ± 0.6 Hz
(calculated: 1.8 — 2.7 Hz)
absorption coefficient: ~ 5 • 10-7
STREGA kick-off meeting, Cascina 12 May 2004
T2
INFN-LENS
Photothermal effect…
First 18 months
… for different interrogation area
… for different transversal modes
Then
… for different substrates (silica, sapphire)
… at low temperature (bar detector readout)
Collaboration: Auriga-PD, LKB, INOA, …
STREGA kick-off meeting, Cascina 12 May 2004
T3
INFN-LENS
Folded Fabry-Pérot
-35
10
Pin =W
7W
Pin=7
D = 6 mm
R = - 10 m
d =4w
-36
10
M3
10
10
10
M2
(a) Lett. A 309, 15 (2003)
F. Marin et al., Phys.

-38
-1
(Hz )
M3
2

M1
S / 
M4
M1
-37
-39
b
a
-40
10
c
-41
d
M2
50
100
e
10
(b)
-42
10
0
150
200
250
300
350
N
Brownian noise
2L
single
S Br
S Br
1


 2 (2L) 2 2D 2 N
S
a: radiation pressure effect (no correlations)
b: radiation pressure effect (full)
c: Brownian noise @ 1.3 kHz (no correlations)
d: Brownian noise @ 1.3 kHz (full)
2L
single
S
S
S
1

RP
RP
Radiation Pressure


 2 (2L) 2 4D 2 N 2
noise
e: Shot-noise limited displacement sensitivity
STREGA kick-off meeting, Cascina 12 May 2004
T3
INFN-LENS
Concave -Convex cavity
-R
(-R2) = R1 + r
Stable if d > r
If (d – r) << d << R1, R2 :
Ex. : R = 10 m
r = 10 mm
d – r = 0.1 mm
l = 1.064 mm
R+r
d
λR
d
w 
π dr
2
w = 5.8 mm
STREGA kick-off meeting, Cascina 12 May 2004
T3
INFN-LENS
First 18 months
Folded and Concave-Convex cavities: opto-mechanical
feasibility
Then
Noise reduction characterization, possibly at low
temperature
Collaboration: Auriga-PD, LKB,INOA, …
STREGA kick-off meeting, Cascina 12 May 2004