electronics for pulse pickers - OEM Tech
PRELIMINARY SPECIFICATION rev. 2.02 / 2011 06 28
ELECTRONICS FOR PULSE PICKERS TABLE OF CONTENTS Description .................................................................................................................................................................... 2 High voltage switches .................................................................................................................................................... 3 Power ratings............................................................................................................................................................. 3 Short pulse modification ........................................................................................................................................... 3 Long pulse modification ............................................................................................................................................ 3 Specifications ............................................................................................................................................................. 4 How to order? ........................................................................................................................................................... 4 High voltage power supplies ......................................................................................................................................... 5 Specifications ............................................................................................................................................................. 5 The control board (the control unit) ............................................................................................................................. 6 Connections ............................................................................................................................................................... 6 Time diagram and the synchronization ..................................................................................................................... 7 RS‐232 interface commands desription .................................................................................................................... 7 Photodiode’s threshold and triggering ...................................................................................................................... 8 Specifications ............................................................................................................................................................. 8 Photodiode assemblies ................................................................................................................................................. 9 Software ........................................................................................................................................................................ 9 Examples of usage ....................................................................................................................................................... 10 Simple pulse picking ................................................................................................................................................ 10 Regenerative amplifier control ................................................................................................................................ 10
DESCRIPTION There is a typical task in the laser industry – resampling down the repetition rate of pulsed lasers. Most commonly this task is related to pico‐ and femtosecond lasers and is known there as pulse picking. Typical seed laser has the repetition rate of tens of MHz (from 10MHz up to 100MHz or even more). For further amplification the repetition rate of tens of kHz is needed. As a result some kind of pulse picker is required. The electro‐optical crystal like RTP, DKDP or BBO, simply assembled together with the polarizer, and properly driven with the high voltage electronics can select and transmit some of optical pulses from the pulse train and reject all others.
E-O crystal
polarizer
polarizer
Controlling and driving electronics
In the similar way input/output of pulses into/from the regenerative amplifier may be controlled.
Active media
E-O crystal
1 λ/4 plate
HR mirror
polarizer
HR mirror
The leading edge of electrical pulse (of L/4 voltage) should be applied when the optical pulse is passing through the area 1. The falling edge of electrical pulse applied when the optical pulse is in area 1 again will release the optical pulse from the amplifier.
HIGH VOLTAGE SWITCHES The first key element of aforementioned schemes is the high voltage switch capable to produce pulses with very fast rise and fall times (
ELECTRONICS FOR PULSE PICKERS TABLE OF CONTENTS Description .................................................................................................................................................................... 2 High voltage switches .................................................................................................................................................... 3 Power ratings............................................................................................................................................................. 3 Short pulse modification ........................................................................................................................................... 3 Long pulse modification ............................................................................................................................................ 3 Specifications ............................................................................................................................................................. 4 How to order? ........................................................................................................................................................... 4 High voltage power supplies ......................................................................................................................................... 5 Specifications ............................................................................................................................................................. 5 The control board (the control unit) ............................................................................................................................. 6 Connections ............................................................................................................................................................... 6 Time diagram and the synchronization ..................................................................................................................... 7 RS‐232 interface commands desription .................................................................................................................... 7 Photodiode’s threshold and triggering ...................................................................................................................... 8 Specifications ............................................................................................................................................................. 8 Photodiode assemblies ................................................................................................................................................. 9 Software ........................................................................................................................................................................ 9 Examples of usage ....................................................................................................................................................... 10 Simple pulse picking ................................................................................................................................................ 10 Regenerative amplifier control ................................................................................................................................ 10
DESCRIPTION There is a typical task in the laser industry – resampling down the repetition rate of pulsed lasers. Most commonly this task is related to pico‐ and femtosecond lasers and is known there as pulse picking. Typical seed laser has the repetition rate of tens of MHz (from 10MHz up to 100MHz or even more). For further amplification the repetition rate of tens of kHz is needed. As a result some kind of pulse picker is required. The electro‐optical crystal like RTP, DKDP or BBO, simply assembled together with the polarizer, and properly driven with the high voltage electronics can select and transmit some of optical pulses from the pulse train and reject all others.
E-O crystal
polarizer
polarizer
Controlling and driving electronics
In the similar way input/output of pulses into/from the regenerative amplifier may be controlled.
Active media
E-O crystal
1 λ/4 plate
HR mirror
polarizer
HR mirror
The leading edge of electrical pulse (of L/4 voltage) should be applied when the optical pulse is passing through the area 1. The falling edge of electrical pulse applied when the optical pulse is in area 1 again will release the optical pulse from the amplifier.
HIGH VOLTAGE SWITCHES The first key element of aforementioned schemes is the high voltage switch capable to produce pulses with very fast rise and fall times (
