Theoretical Optimization of a DAVLL System for a Rubidium Vapor
Joel A. Greenberg, Andrew M. C. Dawes, Daniel J. Gauthier
Quantum Electronics Lab, Physics Department, Duke University
Experimental Data
Introduction
0.02
MOTIVATION:
Experimental Setup
λ/4 plate
Polarizer
PBS
Here we show
sensitivity to B field
changes
0.015
GHz-1/G
• Model and optimize a simple, robust,
laser frequency lock system
Sensitivity of Slope to B
Vapor
Cell
0.01
0.005
0
0.005
0.01
METHOD:
125
LASER
σ–
σ+
2
1 0
1
2
Model vs. Experiment
For B≠0
Absorption Scan
4
Absorption
Difference Signal
1
Transmission
0.9
0.8
0.7
0.6
0.5
Temp (K)
4000
2000
0
2000
2
1
0
1
2
3
4
4000
3000
3500
4000
4500
5000
Frequency (MHz)
Data
Here we show
sensitivity to
temperature changes
0.05
0
0.05
0.1
Temp (K)
Sensitivity of Lock Pt to T
0.1
2
I 0   ( H ,T ) L   ( H ,T ) L
I  (e
e
)
2
MHz/K
0.05
H ( B)Tot  H 0  H FS  H HFS  H Laser
358
0
Indicates
optimal pt
0.1
0.2
0.3
125
150
175
200
225
250
275
0
0.05
0.1
B Field(G)
Within ± 5 K and ±2.5 G of the optimum
conditions, the signal fluctuates as:
• slope sensitivity:
<0.5 (1/GHz)/K
<0.1 (1/GHz)/G
• lock point sensitivity:
0 ± 10 KHz/K
50 ± 50 KHz/G
• capture range variation: 0 ± 20 MHz/K
4 ± 1 MHz/G
100
220
140
260
Citations
180
280
1) Corwin, Lu, Hand, Epstein, Wieman: Appl. Opt. 37, 3295 (1998)
Indicates
optimal pt
0.15
Conclusions
Capture range = 0.5 GHz
290 300 310 320 330 340 350 360
Hamiltonian
314
B~260 G, T~335 K
Slope = 2 GHz-1
Sensitivity of Slope to T
The Model
338
Optimal conditions for a D2 lock in a 7.5cm Rb87 cell:
Optimization
GHz-1/K
Choose the combination of B and T which :
• Provides a large but insensitive slope
• Provides a difference signal with an
insensitive lock point
• Produces a signal which is suitably linear
• Produces a broad capture range
302
0.01
Model
3
326
0
Frequency (MHz)
4
290
B Field (G)
0.01
0.02
GOALS:
Output intensity
275
0.1
0.4
0.02
Difference Signal
σ+ - σ-
3
250
0.3
M = +1
Difference Signal
3
225
Sensitivity of Lock Pt to B
MHz/G
M=0
Diff Signal
M = -1
Absorption Profile
4
Permanent
Magnets
Detectors
• Subtracting the shifted absorption signals
produces a dispersion-like curve suitable as an
error signal
σ+
200
0.2
• Resonant frequencies
shift down/up for σ+/σ-
σ-
175
B Field (G)
Dichroic Atomic Vapor Laser Lock (DAVLL) 1
• Zeeman effect shifts
energy levels
150
2) Beverini, Marsili, Ruffini, Sorrentino: Appl. Phys. B 73, 133-138
(2001)
290 300 310 320 330 340 350 360
Temp (K)
Funding
US Army Research Office (grant # W911NF-05-1-0228)