Speaker
Description
We describe a timing-stabilized RF amplitude and phase monitor, using optical interferometry. Unlike RF-over-fiber using AM, RF voltage drives an EO phase modulator at the sensor. No bias is needed, and light is provided by the receiving system. The optical signal goes back through fiber and is interfered with an optical LO at the receiver, a coherent telecom component with optical I and Q channels for X and Y polarizations. This produces RF signals to be demodulated, with a result linearly proportional to the sensed voltage. The roundtrip optical phase change can be used to time correct the RF signal, providing data for feedback control while the fiber delayvaries due to thermal and acoustic effects. One can get polarization state data from the receiver to drive a polarization controller, aligning light to the axis of the EO phase modulator. We show simulations using ANSYS, compared with early experimental results using a single-channel interferometer and our FPGA-based DSP. We demonstrate RF transmission and reception, detecting amplitude and phase with correction for optical phase instability. With a fast digitizer,this sensing system can be used for temporally stable BPM and BAM signals. The scheme is capable of extension to multiple channels mutually synchronized.
| Abstract Classification | Sensors and actuators |
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