Optimizing a Highly Optimizing a Highly Stable Diode Laser for Stable Diode Laser for

Spectroscopy and Atom Spectroscopy and Atom TrappingTrapping

John E. SohlJohn E. Sohl

Caleb Z. TrammellCaleb Z. Trammell

Weber State UniversityWeber State University

Ogden, UTOgden, UT

OverviewOverview

Brief HistoryBrief History

What is an ECDL?What is an ECDL?

Carl Wieman’s ECDL designCarl Wieman’s ECDL design

Other ECDL designsOther ECDL designs

Our ECDL designOur ECDL design

Results and current statusResults and current status

HistoryHistoryCarl Wieman’s group, AJP papers:Carl Wieman’s group, AJP papers: 1992: A narrow-band tunable diode laser 1992: A narrow-band tunable diode laser

system with grating feedback, and a saturated system with grating feedback, and a saturated absorption spectrometer for Cs and Rb.absorption spectrometer for Cs and Rb.

1995: Inexpensive laser cooling and trapping 1995: Inexpensive laser cooling and trapping experiment for undergraduate laboratories.experiment for undergraduate laboratories.

Nobel Prizes:Nobel Prizes: 1997: Laser trapping1997: Laser trapping 2001: BEC2001: BEC

1999: NSF workshops1999: NSF workshops

Current StatusCurrent Status

Numerous papers on improved laser Numerous papers on improved laser design since ~1999.design since ~1999.

Moderate number of undergraduate Moderate number of undergraduate laboratories doing saturated absorption.laboratories doing saturated absorption.

A few doing atomic trapping.A few doing atomic trapping.

Why? Not Easy and Laser StabilityWhy? Not Easy and Laser Stability

Goal: Wavelength StabilityGoal: Wavelength Stability

These issues have been covered in our other These issues have been covered in our other paper today.paper today.

Cavity size (mode spacing and Cavity size (mode spacing and oror))

Thermal mass and stabilityThermal mass and stability

Ease of construction and operationEase of construction and operation

nL

mcm 2

Laser Gain ProfilesLaser Gain ProfilesFrom: S.J.H. Petra, 1998

Laser DesignLaser Design

Extended Cavity Extended Cavity Diode Laser – Diode Laser – ECDLECDL

Feedback from the Feedback from the diffraction grating diffraction grating (G) forces the (G) forces the wavelength to a wavelength to a specific value.specific value.

Other DesignsOther Designs

1997

1998

2000

Our DesignOur Design

SimpleSimple

Easy to align and Easy to align and assembleassemble

Easy to buildEasy to build

InexpensiveInexpensive

Low thermal massLow thermal mass

Short cavityShort cavity

Results and Current StatusResults and Current Status

Laser has been built and is being tested.Laser has been built and is being tested.

Earlier modifications have resulted in Earlier modifications have resulted in frequency stability of ~300 kHz (<1 part in frequency stability of ~300 kHz (<1 part in ~10~1088) for several hours at a time. (Wieman ) for several hours at a time. (Wieman got 3.5 seconds.)got 3.5 seconds.)

Expecting factor of 3 improvement with Expecting factor of 3 improvement with new design. new design.

Should be operational in 2-3 days.Should be operational in 2-3 days.