THORLABS PDB440A, Operation Manual, Page: 5 / 29

© 2019 Thorlabs
1 General Information
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1 General Information
Thorlabs PDB440x and PDB450x detectors Balanced Amplified Photodetectors consist of two
well-matched photodiodes and an ultra-low noise, high-speed transimpedance amplifier that
generates an output voltage (RF OUTPUT) proportional to the difference between the photo
currents in the two photodiodes, i.e. the two optical input signals. Additionally, the unit has two
fast monitor outputs ( and MONITOR-) to measure the individual optical input
power level as well as low frequency modulated signals on each detector separately.
To the PDB440x and PDB450x detectors housing an adapter can be attached to the bottom or
side surface for post mounting. This adapter supports #8-32 as well as M4 post mounts.
The PDB440x and PDB450x detectors is supplied with an external linear power supply.
The “Getting Started” section gives an overview of how to set up the PDB440x and PDB450x
detectors Balanced Amplified Photodetectors. Subsequent sections contain detailed informa-
tion about principle of operation, operating suggestions, and technical specifications.
1.1 Safety
Attention
The safety of any system incorporating the equipment is the responsibility of the assem-
bler of the system.
All statements regarding safety of operation and technical data in this instruction manual
will only apply when the unit is operated correctly as it was designed for.
The PDB440x and PDB450x detectors must not be operated in explosion endangered en-
vironments!
Do not remove covers!
Do not open the cabinet. There are no parts serviceable by the operator inside!
This precision device is only serviceable if properly packed into the complete original
packaging including the plastic foam sleeves. If necessary, ask for replacement pack-
aging.
Refer servicing to qualified personnel!
Only with written consent from Thorlabs may changes to single components be made or
components not supplied by Thorlabs be used.
1.2 Ordering Codes and Accessories
The following models of the PDB440x and PDB450x detectors are available:
PDB440 15 MHz, OCT-proved fixed gain Balanced Amplified Photodetectors with active
aliasing filter
PDB450 up to 150 MHz, gain switchable Balanced Amplified Photodetectors
According to Thorlabs general detector part numbering system, the suffix “A” indicates Si pho-
todiodes while the suffix “C” indicates InGaAs photodiodes.
Thorlabs offers AC-coupled versions. on request Special versions (open detector - cover glass
removed) are available as well - please contact
Thorlabs for details.
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