High resolution spectroscopy with a femtosecond laser

frequency comb

Vladislav Gerginov1

Scott Diddams2, Albrecht Bartels3, Carol E. Tanner1 and Leo Hollberg2

1Department of physics, University of Notre Dame, Notre Dame, IN 465562National Institute of Standards and Technology, 325 Broadway M.S. 847, Boulder, CO 80305

3Gigaoptics GmbH (see exhibit)

Pulsed laser spectroscopy1970s: Ideas of 2-photon spectroscopy with pulsed sources from T. W. Hänsch and V. P. Chebotaev;

“Narrow resonances of two-photon absorption of super-narrow pulses in a gas” Y. V. Baklanov and V. P. Chebotaev, Appl. Phys. 12, 97 (1977).

“Coherent Two-Photon Excitation by Multiple Light Pulses”R. Teets, J. Eckstein, and T. W. HänschPhys. Rev. Lett. 38, 760-764 (1977).

“Two-photon spectroscopy of laser-cooled Rb using a mode-locked laser”, M. J. Snadden, A. S. Bell, E. Riis, A. I. Ferguson, Opt. Commun, 125, 70-76, (1996).

“High sensitivity phase spectroscopy with picosecond resolution”J. –C. Diels, B. Atherton, S. Diddams;Proceedings of 5th European Quantum Electronics Conference, 29 195–195, (1994).

“United Time-Frequency Spectroscopy for Dynamics and Global Structure”, A. Marian, M. C. Stowe, J. R. Lawall, D. Felinto, J. Ye, Science Express, 1105660, 2004.

Direct single-photon spectroscopy using a femtosecond laser

Bartels et al., Opt. Lett. 27(20) 1839, 2002 Bartels et al., Opt. Lett. 29,10,1081,2004

133Cs energy diagram and FLFC output spectrum

Experimental setupOptical frequency measurements

D1 line @ 14nW power D2 line @ 1.5 nW power

D1 line measurements

F-F’ Previous1 (kHz) This work (kHz) Difference (kHz)

F3-F3 335120562759.7(4.9) 335120562753.7(85.0) -6.0 ( 0.1 sigma)

F3-F4 335121730483.2(5.3) 335121730500.8(16.4) 17.6 (1 sigma)

F4-F3 335111370130.2(4.6) 335111370146.3(10.5) 16.1 (1.4 sigma)

F4-F4 335112537853.9(4.0) 335112537861.7(28.0) 7.8 ( 0.3 sigma)

1V. Gerginov, K. Calkins, C. E. Tanner, A. Bartels, J. McFerran, S. Diddams, L. Hollberg, in preparation

F-F’ Previous1 (kHz) This work (kHz) Difference (kHz)

F3-F2351730549621.5)5.5

(351730549616.3)9.7( -5.2) 0.5 sigma(

F3-F3351730700845.9)5.5

(351730700766.1)98.5( -79.8)0.8 sigma(

F3-F4351730902133.2)5.6

(351730902116.9)34.2( -16.3) 0.5 sigma(

F4-F3351721508210.5)5.5

(351721508195.1)21.7( -15.4) 0.7 sigma(

F4-F4351721709496.9)5.5

(351721709471.6)167.8

(-25.3 )0.2 sigma(

F4-F5351721960585.7)5.5

(351721960563.5)4.5( -22.2 )3 sigma(

D2 line measurements

1V. Gerginov, C. E. Tanner, S. Diddams, A. Bartels, L. Hollberg, PRA 70, 042505, 2004

Experimental setupCs D2 line optical clock

Cs D2 line optical clock performance

Conclusions

Optical frequency measurements using a single comb component;

A stable array of optical and microwave frequencies;

Potential for femtosecond-laser based optical clocks;

Typical optical references performance

Typical optical frequency reference uncertainties:

This system: 60kHz @ 852nm (1.7×10-10)

I2 stabilized He-Ne laser: 12 kHz @ 633 nm (2.5×10-11)

I2 stabilized SHG of Nd:YAG: 5 kHz @ 532 nm (9×10-12)

Rb 2-photon stabilized diode laser: 5 kHz @ 778nm (1.2×10-11)

GPS: <1kHz with 1-2 days of averaging

Conclusions1. One-photon high resolution spectroscopy using the output of a

femtosecond laser;

2. Optical frequency measurements with accuracy better than 100kHz, reaches below 10 kHz;

3. SubDoppler spectroscopy with 1nW laser power;

4. Optical and microwave output with absolute accuracy at 10-10 level;

5. Potential for femtosecond-laser based optical clocks.

Doppler shift compensation

D2 line excitation