200 MHz TTL-analog photodetector

PD200T - Photodetector with integrated comparator
PD200T - Photodetector with integrated comparator PD200T - Diagram PD200T - Pulse detection PD200T - PRBS modulation

Koheron PD200T is an InGaAs photodetector with a dual TTL-analog output. The analog output has a gain of 500 V/A and a 200 MHz bandwidth. The TTL output has 2.5 ns propagation delay, 1.3 ns rise time and 0.7 ns fall time. Trigger threshold can be adjusted with a precision trimmer.

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Wavelength range 900 - 1700 nm
Optical input power 0 - 2 mW
Noise Equivalent Power 30 pW/√Hz (at 100 kHz)
Analog output
Small signal bandwidth 200 MHz at 3 dB
Impulse response 2 ns (FWHM)
Transimpedance gain 500 V/A (Hi-Z), 250 V/A (50 Ω)
Analog output impedance 50 Ω
Analog output dark offset 10 mV
Analog output current max 80 mA
Analog output voltage 3 Vpp (Hi-Z), 1.5 Vpp (50 Ω)
Analog output slew rate 400 V/µs (50 Ω), 600 V/µs (Hi-Z)
TTL output
TTL rise / fall time 1.5 ns
Logic low 0.1 V (max. Hi-Z), 0.05 V (max. 50 Ω)
Logic high 2.6 V (min. Hi-Z), 1.3 V (min. 50 Ω)
TTL output current max 20 mA
TTL output impedance 50 Ω
Power Supply 3.7 - 15 VDC
Photodiode connector FC
Photodiode peak responsivity 0.90 A / W
Output connectors SMA
Outside Dimensions 48 mm x 53 mm x 14 mm
Weight 20 g
Mechanical details Compatible with M6 metric breadboards (25 mm spacing)
Operating temperature 0 °C - 50 °C

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Functional diagram

Functional diagram


Pulse detection

We operated the Koheron LD100 laser in pulsed-mode (width of 10 ns, pulse period of 100 ns, 10 Vpp modulation). The laser average output power was 850 µW. Half of this power was used to feed the PD200T. Trigger threshold was adjusted to 1.0 V. The figure below shows the analog output (in blue) and the TTL output (in purple) observed on an oscilloscope:

Pulse detection

Propagation delay between the analog and the TTL output is about 2.5 ns. TTL rise and fall times (10 to 90 %) are 1.3 ns and 0.7 ns, respectively.

PRBS modulation

We modulated the Koheron LD100 laser with a 100 Mbps pseudo random binary sequence (PRBS) shown in yellow in the figure below. The green curve represents the modulation detected by the 100 MHz photodetection of the LD100. The analog and TTL output of the PD200T are shown in blue and red, respectively.

100 Mbps PRBS

The 25 ns delay between the laser modulation (in orange) and the PD200T analog output (in blue) corresponds to the 5 m fiber between the laser and the PD200T.

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Revision history

  • 2: FC Photodiodes

Export information

HS code 8541.40.90
Country of Origin France

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