pulseSelect
Reducing the Repetition Rate of Mode-locked Lasers with a Pulse Picker
Suitable for fs and ps Mode-locked Lasers
Acousto-Optical Single Pulse Selector
pulseSelect is an acousto-optical pulse picker, developed for the special demands of femtosecond laser technology. Pulse distortion is minimized by a low dispersive design and the use of reflective optics. High repetition rates and high contrast rates are achieved by using acousto-optical elements.
The pulse repetition rate can be reduced by an adjustable internal frequency divider or by external triggering. Pulse picking with low division ratios down to fREP/2 are possible. pulseSelect has an integrated RF power limitation and protection circuit to prevent modulator damage. For highest stability the phase of the RF carrier frequency is locked to the repetition rate of the laser in use.
At a Glance
Reduction of the repetition rate of mode-locked lasers
fs or ps mode-locked laser (e.g. Ti:Sapphire)
Low dispersion design suitable for ultra-short pulses down to < 20 fs
Division ratio continuously variable between fREP/2 … fREP/260,000
Synchronized to laser seed with internal trigger
Single-shot up to 3 MHz with external TTL trigger
External trigger-gate mode
Single Stage Pulse Picker with pulseSelect
The Single pulseSelect consists of an optical module and control electronics. A Bragg cell represents the most important part of the optics, which selects individual pulses from the laser beam due to the acousto-optical effect. Focusing mirror, collimator mirror and a beam stop for the zero-order beam complete the setup. The driver electronics supplies the modulated RF signal for the Bragg cell with a carrier frequency that corresponds to the multiple of the laser repetition rate.
Double Stage Pulse Picker
pulseSelect in a double configuration is available in two variants, Serial and Parallel. The Serial variant offers an improved contrast ratio of over 6000:1. The Parallel version allows the simultaneous picking of pulses from two synchronized laser sources.
Double pulseSelect Serial: This version is designed to allow for highest contrast ratio of above 6000:1 by placing two Bragg cells. Both are synchronized to one common clock (in serial configuration; i.e. one beam through two Bragg cells).
Double pulseSelect Parallel: This variant is designed for simultaneous picking of pulses from two synchronized laser sources. The system is equipped with two synchronized Bragg cells. Independent picking settings are possible for both Bragg cells.
Specifications
pulseSelect Specification Wavelength Ranges
(Other ranges on request)pulseSelect Broadband
500 ... 1600 nm
pulseSelect Dualband
340 ... 540 nm + 680 ... 1080 nmMax. Laser Input Power
5 W (at 800 nm)
Input Frequency (fREP)
(to be specified with 0.5 MHz at the time of order)
accuracy at time of order)72 ... 81 MHz
Input Polarization
Horizontal (polarization rotator optional)
Output Repetition Rate (based on 80 MHz input frequency)
Single-shot … 40 MHz;
External Trigger based: Single-shot … 3 MHz
Internal Trigger based: ~ 308 Hz … ~ 40 MHz (only integer values of input repeptition rate are available)Division Ratio (internal trigger)
fREP/2 ... fREP/260,000
Contrast Ratio (at 800 nm, fREP/20)
> 75 : 1 for adjacent pulses;
> 500 : 1 for non-adjacent pulsesDiffraction Efficiency*
> 50% (at 800 nm, fREP/20)
*Ratio of the diffracted pulse energy to the pulse energy incident into Bragg cell
pulseSelect Dual - Serial
Application
High-contrast performance
Contrast Ratio (at 800 nm, fREP/20)
> 5000 : 1 for adjacent pulses;
> 200.000 : 1 for non-adjacent pulsesDiffraction Efficiency*
> 25% (at 800 nm, fREP/20)
*Ratio of the diffracted pulse energy to the pulse energy incident into Bragg cell
pulseSelect Dual - Parallel
Application
Simultaneous picking of pulses from two synchronized laser sources
Contrast Ratio (at 800 nm, fREP/20)
> 75 : 1 for adjacent pulses;
> 500 : 1 for non-adjacent pulsesDiffraction Efficiency*
> 50% (at 800 nm, fREP/20)
*Ratio of the diffracted pulse energy to the pulse energy incident into Bragg cell
Options
Input Frequency
35 … 90 MHz (to be specified with 0.5 MHz accuracy at time of order)
High Diffraction Efficiency
> 60% (36% for pulseSelect Dual - Serial),
only available for max average input power of 0.5 WPolarization Rotator
Changing input polarization to horizontal
* These values depend on a certain system configuration, e.g. laser spot diameter, or mirror coating
** Ratio of the diffracted pulse energy to the pulse energy incident into Bragg cell
描述 [描述] Reducing the Repetition Rate of Mode-locked Lasers with a Pulse Picker