The Light Source

A Titanium Sapphire pulsed laser serves as the light source for fluorescent lifetime experiments. This laser's tunable wavelength range of 700nm to 980nm is extended to include 350nm to 490nm by use of an optical frequency doubler (right side of photo). An optical frequency tripler further extends this range to include 233nm to 327nm. An acousto-optic pulse picker (left side of photo) is used to lower the laser's pulse rate for longer-lifetime fluorophores.

Laser/Oscillator:

Coherent Mira 900-D Ti-Sapph Mode-locked femtosecond oscillator cavity with Optima Controller

Wavelength Range: 700nm-980nm

Pulse Repetition Rate: 76MHz

Pulse Width: <200 femtoseconds

Coherent 10W Verdi Diode laser pump for Mira

Optical Harmonic Generators:

Coherent Frequency Doubler

Efficiency at 950nm with 0.275 watt Mira input: Measured to be 4.5%

UOPlaz Frequency Tripler

Efficiency at 860nm with 0.64 watt Mira input: Measured to be 8.3%

Pulse Picker:

NEOS Acousto-optic pulse picker with Driver

Picking ratios: 1:10, 1:20, 1:50, 1:100, 1:200, 1:500, 1:1000

Efficiency (1:10 ratio) at 900nm with 0.7 watt Mira input: Measured to be 40% under maximum rejection conditions

Note: Efficiency is less with horizontally polarized input (this is the case with the Mira laser)

Adjacent pulse height (@1:10 divide-down): Measured at 800nm to be 20% / Measured at 900nm to be 45%

Last updated August 10, 2003