High transimpedance gain and low noise
Silicon or InGaAs versions
AC & DC coupled versions
Free-space and fiber-coupled versions
Excellent RF shielding
125 MHz photoreceivers offer a well-balanced combination of gain, bandwidth, and low noise over the DC–125-MHz frequency range. Because of their high transimpedance gain and low noise-equivalent power (NEP), they offer the best in sensitivity for signals with rise and fall times as short as 3 ns. This high sensitivity, combined with their high-level output, reduces the effects of downstream noise sources. They have been engineered to eliminate most common sources of noise and drift, and have enough gain to pick up even very weak signals making them ideal optical front ends for systems requiring a low-noise input.
Silicon models provide visible wavelength coverage from 320-1000 nm and use a silicon-PIN photodiode with a high-gain, low-noise transimpedance amplifier. The near-IR version uses an InGaAs-PIN photodetector that provides coverage from 900-1700 nm.
Typical frequency response (top) and noise floor (bottom) for Models 1801 and 1811. At DC the noise floor is 3.3 pW/ for the Model 1801, and 2.5 pW/ for the Model 1811.
Because of their high transimpedance gain and low noise-equivalent power (NEP), they offer the best in sensitivity for signals with rise and fall times as short as 3 ns. This high sensitivity, combined with their high-level output, reduces the effects of downstream noise sources.
With true DC coupling, these photoreceivers give linear responses to transient signals without artificial ringing, tails, or other anomalies.
AC-coupled versions with a low-frequency roll-off at 25 kHz are available. These photoreceivers are useful for measuring a small AC signal on a large cw component. To make alignment easier, AC-coupled versions are equipped with a DC photocurrent monitor output. The monitor output has a 50-kHz bandwidth and a gain of 1 V/mA.
Careful RF shielding and filtering of power-supply inputs eliminate electromagnetic interference, even in laboratories with Q-switched lasers and other noisy equipment.
| 1801-FC | 1801-FS | 1801-FC-AC | 1801-FS-AC | 1811-FC | 1811-FS | 1811-FC-AC | 1811-FS-AC | |
|---|---|---|---|---|---|---|---|---|
| Wavelength Range (nm) | 320-1000 | 320-1000 | 320-1000 | 320-1000 | 900-1700 | 900-1700 | 900-1700 | 900-1700 |
| Bandwidth (-3 dB) | 125 MHz | 125 MHz | 25 kHz to 125 Mhz | 25 kHz to 125 Mhz | 125 MHz | 125 MHz | 25 kHz to 125 Mhz | 25 kHz to 125 Mhz |
| Rise Time (ns) | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 |
| Conversion Gain, Maximum (V/W) | 4x104 | 4x104 | 4x104 | 4x104 | 4x104 | 4x104 | 4x104 | 4x104 |
| Responsivity (Peak) () | 0.5 A/W @ 800 nm | 1.0 A/W @ 1550 nm | 1.0 A/W @ 1550 nm | 1.0 A/W @ 1550 nm | 1.0 A/W @ 1550 nm | |||
| Maximum Transimpedance Gain () | 4x104V/A | 4x104V/A | 4x104V/A | 4x104V/A | 4x104 V/A | 4x104 V/A | 4x104 V/A | 4x104 V/A |
| DC Bias Monitor BW (AC version only) () | 50 KHz | 50 KHz | 50 KHz | 50 KHz | ||||
| DC Bias Monitor Transimpedance Gain (V/mA) | 10 | 10 | 10 | 10 | 10 | 10 | 10 | 10 |
| Output Impedance (Ω) | 50 | 50 | 50 | 50 | 50 | 50 | 50 | 50 |
| NEP (pW/√Hz) | 3.3 | 3.3 | 3.3 | 3.3 | 2.5 | 2.5 | 2.5 | 2.5 |
| Saturation Power CW () | 110 µW @ 800 nm | 110 µW @ 800 nm | 110 µW @ 800 nm | 110 µW @ 800 nm | 55 µW @ 1550 nm | 55 µW @ 1550 nm | 55 µW @ 1550 nm | 55 µW @ 1550 nm |
| Optical Input | FC | Free Space | FC | Free Space | FC | Free Space | FC | Free Space |
| Detector Diameter (mm) | 0.4 | 0.4 | 0.4 | 0.4 | 0.1 | 0.3 | 0.1 | 0.3 |
| Detector Material | Silicon | Silicon | Silicon | Silizium | InGaAs | InGaAs | InGaAs | InGaAs |
| Output Connector | SMA | SMA | SMA | SMA | SMA | SMA | SMA | SMA |
| Power Requirements | ±15 V, <250 mA | ±15 V, <250 mA | ±15 V, <250 mA | ±15 V, <250 mA | ±15 V, <250 mA | ±15 V, <250 mA | ±15 V, <250 mA | ±15 V, <250 mA |