Large 650-MHz or 800-MHz bandwidth to fit a wide variety of laboratory experiments
25-dB common-mode rejection ratio lets you see your signal
Three convenient photocurrent-monitor outputs
Ideal for FM spectroscopy, absorption spectroscopy, or ellipsometry, these 650- and 800-MHz balanced photoreceivers can make all the difference when you’re trying to see a small signal. They can even eliminate the need for lock-in amplifiers, enabling you to cancel out laser intensity noise in any experimental setup that produces either a reference signal or balanced optical signals. The IR version is especially useful for cancelling out residual intensity noise in heterodyne applications.
Models 1607 and 1617 work by subtracting the photocurrent from two well-matched photodetectors. Common-mode noise that is present on both the reference and signal beams (such as laser intensity noise) is cancelled out and thus doesn’t appear as part of the signal. On the other hand, any imbalance between the photocurrents generated by the reference and signal photodetectors, whether intentional or unintentional, is amplified and is seen as the signal.
Although it is similar to our Model 20X7 auto-balanced photoreceiver, this higher-speed version requires manually equalizing the power between the signal and reference beams. To make this process easier, the photoreceiver includes three low-frequency photocurrent-monitor outputs I1, I2, and I2–I1, as well as the high-frequency RF output. When the optical powers on the two photodetectors are equal, background noise (including laser intensity fluctuations) is cancelled. These balanced photoreceivers contain the same photodetectors as those in our Model 16X1-AC series. The photodetectors are carefully chosen for their well-matched frequency responses and are mounted at 90° with respect to each other (one on each side of the box versus both on the same panel). This unique packaging allows for closer photodetector spacing and, therefore, high-bandwidth performance.
Both free-space (FS) and FC-connectorized versions are available. To ensure safe operation, we strongly recommend our Model 0901 power supply.
The Model 1607-AC balanced photoreceiver is especially useful in measuring absorption properties. Here, a probe beam is focused onto one of the photodetectors while the other detects a reference beam.
Responsivity of the Model 1607-AC (Blue) vs. Model 1617-AC (Black)
Typical frequency response and noise spectrum for Model 1607-AC.
Typical frequency response and noise spectrum for Model 1617-AC.