Multi-Channel And High Precision Optical Power Meter Detection Circuit Research

To avoid some typical drawbacks that traditional laser power detection system has, such as small dynamic range, obvious shift error and inconvenient to extend the acquisition channels, detection methods and techniques of laser power are studied. Fused mechanism of accurate measurement, signal search and monitor tracking are analyzed, and the rules between parameters of detection system are presented. According to the relative research, a large dynamic range, non-shift error, multi-channel parallel acquisition of high-precision optical power detection system is designed.The research work includes the following sections:1. Measurement system noise modelFrom the system noise sources around the noise power spectral density, the noise transfer model is established. And the weak laser power detection system noise analysis method is proposed. Based on the SPICE circuit simulation tool, the noise transfer model simulation analysis result shows that the proposed noise analysis method is feasible, and it provides the basis for the measurement system hardware design.2. Multi-channel laser power meter hardware schemeThe technical difficulties of the system are discussed. Whereby, the master-slave design of hardware is putted forward. The multi-channel laser power meter’s hardware design is mainly build from six aspects, including selecting the photo detector’s parameters, noise matching network, logarithmic amplifier, filter processing, the AD sampling, and the CAN bus.3. Multi-channel laser power meter software schemeAccording to the detection system hardware requirements, the system master board’s control procedures, each acquisition channel’s control programs and optical power data acquisition software on PC are designed. To reduce the sampling error, AD moving average sampling algorithm is adopted.4. Multi-channel laser power meter system experimentsA multi-channel optical power meter experimental prototype is build. The measurement results show that the prototype meets the requirements of the design specifications. The prototype has power range of-70dBm to lOdBm (80dB dynamic range) and0.034dB maximum uncertainty in the channel.