pulseSelectRepetition Rate Reduction for Mode-locked
Lasers with a Pulse Picker
Pulse Picking with pulseSelectpulseSelect 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. 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 RFcarrier frequency is locked to the repetition rate of the laser in use.

At a Glance
Low dispersion design suitable for ultra-short pulses (fs/ps) 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pulseSelect Single & DualSingle 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 theacousto-optical effect. Focusing mirror, collimator mirror and a beam stop for the zero-order beamcomplete the setup. The driver electronics supplies the modulated RF signal for the Bragg cell with acarrier frequency that corresponds to the multiple of the laser repetition rate.

Dual pulseSelectDual pulseSelect 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.

Dual 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).

Bragg Cell
(SiO2 or TeO2)

Bragg Cell
(SiO2 or TeO2)

Dual pulseSelect Parallel: This variant is designed for simultaneous picking of pulses fromtwo synchronized laser sources. The system is equipped with two synchronized Bragg cells.
Independent picking settings are possible for both Bragg cells.

OPO Signal
OutputLASER

Bragg Cell
(SiO2 or TeO2)

OPO
Ti:Sa Output* Sample input configuration (laser, OPO, and beam
routing not included)

Bragg Cell
(SiO2 or TeO2)

pulseSelectSpecifications

pulseSelect SingleVersions

Broadband

High-Power Dualband

Wavelength Ranges (Other ranges on request)

500 ... 1600 nm

340 ... 540 nm + 680 ... 1080 nm

Max. Laser Input Power (PAV)

5 W (at 800 nm)

Input Frequency (fREP)

72 ... 81 MHz, to be specified with 0.5 MHz accuracy at time of order

Input Polarization

Horizontal, Polarization rotator available as option

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 pulses

Diffraction Efficiency*> 50% (at 800 nm, fREP/20)

pulseSelect Dual - Serial
Application

High-contrast performanceContrast Ratio (at 800 nm, fREP/20)> 5000 : 1 for adjacent pulses> 200.000 : 1 for non-adjacent pulses

Diffraction Efficiency*> 25% (at 800 nm, fREP/20)

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 pulses

Diffraction Efficiency*> 50% (at 800 nm, fREP/20)

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 W

Polarization Rotator

Changing input polarization to horizontal* Ratio of the diffracted pulse energy to the pulse energy incident into Bragg cell

pulseSelect Specifications
Diagrams
Typical Diffraction Efficiency over Repetition Rate

Diffraction Efficiency [%]7060
Constant efficiency forsingle shot up to 4 MHz5040

Output repetition rate range(discretly available):~ 308 Hz ... 40 MHz
based on 80 MHz
seed frequency

3020101110.0
40.0
Output Repetition Rate [MHz]Typical Diffraction Efficiency over Wavelength
for Repetition Rates up to 4 MHz

Typical Diffraction Efficiency over Division Ratio
measured with 80 MHz fs-laser at 800 nm

90
Diffraction Efficiency [%]605040302010807060504030201000051015 2025 303540 45 50
Division Ratio

300

500

700

900

1100

1300
1500
Wavelength [nm]Dimensions
Control Box

267 mm x 180 mm x 312 mm (W x H x D)

Optical Head Single

286 mm x 189 ... 224 mm x 385 mm (W x H x D)

Optical Head Dual - Serial

390 mm x 189 mm ... 224 mm x 580 mm (W x H x D)

Optical Head Dual - Parallel

Two units, each: 286 mm x 189 mm ... 224 mm x 385 mm (W x H x D)
Beam
Output105 ... 130

105 ... 130
189 ... 224

385

Beam
Input

APE GmbH
Plauener Str. 163-165|Haus N|13053 Berlin|Germany
T: +49 30 986 011-30

F: +49 30 986 011-333

E: sales@ape-berlin.de
www.ape-berlin.dewww.phototechnica.co.jp〒336-0017 埼玉県さいたま市南区南浦和 1-2-17

TEL:048-871-0067 FAX:048-871-0068

e-mail:voc@phototechnica.co.jp

286

Purge

99

122

HF In

BeamInput

BeamOutput© APE GmbH|January 2021 |Rev. 3.2.0 | Specifications are subject to change without notice.

Diffraction Efficiency [%]70