Thorlabs PDA200C Photodiode Amplifier

Overview

The Thorlabs PDA200C is a benchtop photodiode amplifier designed to convert the small photocurrent generated by a photodiode into a calibrated, easily measured signal across ten selectable current ranges spanning 100 nA to 10 mA. With transimpedance gain settings from 1×10³ to 1×10&sup8; V/A, the Thorlabs PDA200C accommodates everything from extremely low-light photodetection to higher-power optical power monitoring on a single instrument, making it a versatile front end for laboratories that work across a wide dynamic range of optical signal levels.

Housed in a compact benchtop enclosure with a clear 5-digit LED display, the Thorlabs PDA200C reads out current directly in pA through mA, or, when the connected photodiode’s responsivity falls within 0.05 to 2 A/W, in calibrated optical power units from nW to mW. This dual-mode readout means the same instrument can serve both as a general-purpose current amplifier for arbitrary photodiodes and as a calibrated optical power meter front end for supported detector types, reducing the number of separate instruments needed on an optics bench. With engineering support in Muscat, Seven Star LLC supplies the Thorlabs PDA200C across Oman and the wider GCC, with manufacturer-standard calibration data and responsive local technical support.

Working Principle and Engineering Design

The Thorlabs PDA200C is built around clean, low-noise transimpedance conversion. Internally, it uses a virtual-ground transimpedance amplifier topology, presenting an input impedance of approximately 0 Ω at its front-panel BNC photodiode input. This virtual-ground design lets the amplifier work cleanly with essentially any photodiode type, since the near-zero input impedance prevents the photodiode’s junction capacitance from limiting response speed the way a high-impedance load would. The amplifier supports photodiodes with capacitance up to 10 nF, covering the vast majority of standard silicon, germanium and InGaAs photodetectors used in visible and near-infrared applications.

Bandwidth on the Thorlabs PDA200C scales with the selected gain range, from roughly 500 kHz on the least sensitive, highest-current ranges down to about 1 kHz on the most sensitive 100 nA range — a standard and expected tradeoff in transimpedance amplifier design, since higher gain resistors introduce proportionally more bandwidth-limiting capacitance. A rear-panel ANALOG OUT BNC connector outputs a signal proportional to the photodiode current, scaled to 0 to ±10 V, allowing the Thorlabs PDA200C to feed an oscilloscope, DAQ card, or lock-in amplifier for further signal processing, while a rear 4 mm banana jack provides a chassis ground reference point.

Key Features

The Thorlabs PDA200C packs a broad feature set into a compact benchtop chassis. Ten selectable current ranges from 100 nA to 10 mA give the Thorlabs PDA200C enough dynamic range to cover most photodetection tasks without switching instruments, and the 5-digit LED display can present readings either as raw current (pA to mA, with dedicated indicator LEDs for each decade) or as calibrated optical power (nW to mW) when photodiode responsivity is known and within the supported 0.05–2 A/W range. Bias voltage can be applied to the connected photodiode and toggled from the front panel, useful for photodiodes that require reverse bias for optimal speed or linearity.

The Thorlabs PDA200C’s front-panel SET/CAL controls allow the user to configure bias mode, current or power display, and calibration parameters directly at the bench without external software, and the analog output makes the instrument easy to integrate into existing data acquisition setups. Universal power input support (100/115/230 V, 50–60 Hz) makes the unit usable in Oman and across the GCC without needing a separate step-down transformer, and the manufacturer-specified 10-minute warm-up period ensures rated accuracy is reached before critical measurements begin.

Industrial Applications

The Thorlabs PDA200C is used across a range of measurement-intensive settings. In photonics and laser characterization labs, the Thorlabs PDA200C is commonly used to measure low-level optical signals from custom or non-standard photodiodes that fall outside the range of typical handheld optical power meters, particularly where a specific photodiode’s known responsivity curve needs to be paired with a general-purpose calibrated amplifier. Fiber-optic test and alignment setups use the PDA200C’s fast, low-noise current-to-voltage conversion to provide real-time feedback during coupling optimization, where the analog output can drive a live display or feed an automated alignment routine.

Beyond alignment work, the PDA200C also supports demanding research measurements. Applications in spectroscopy, LIDAR receiver characterization and photodetector qualification testing rely on its wide gain range to characterize photodiodes across many orders of magnitude of incident optical power without swapping amplifiers. Quality-control and calibration labs also use it as a reference-grade transimpedance amplifier when verifying the responsivity or dark current of photodiodes from a production line, since its ten selectable ranges and bias capability cover most standard photodiode test protocols in a single benchtop unit. Seven Star LLC supplies the Thorlabs PDA200C to laboratories, industrial facilities and research institutions throughout Oman, Muscat and the Sohar and Salalah economic zones, with lead time confirmed at quotation.

Technical Specifications

The table below summarizes the key measurement, interface, and power specifications of the Thorlabs PDA200C to help you match the amplifier to your photodiode and application.

Request a Quote for Thorlabs PDA200C Photodiode Amplifier

Seven Star LLC supplies the full Thorlabs precision photonics instrumentation line across Oman and the wider GCC region. For lead times or technical guidance on matching this amplifier to your photodiode and measurement application, contact our engineering team for application support. Whether you need a general-purpose transimpedance amplifier or a calibrated optical power front end, we can help you specify the right configuration for your lab, with manufacturer documentation and regional technical support.

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