An analog fiber optic link developed for electrical pulse signal transmission

The electromagnetic interference (EMI) around the devices for ionizing radiation experiments is a serious concern. In order to reduce EMI and enhance the signal-to-noise ratio, a new type of analog fiber optic link (FOL) has been developed for fast pulse signal transmission under complicated electromagnetic fields. Electrical signals are converted to optical signals through an electro-optical conversion process using the amplitude modulation mechanism. After long-distance transmission, optical signals can also be restored via photoelectric conversion. Each link has a transmitter unit connected via a fiber optic cable to the receiver unit. The transmitter unit consists of a distributed feedback laser, a driver circuit made of amplifiers, and an automatic temperature control module, while the receiver unit consists of a PIN detector, a transimpedance amplifier, a main amplifier, and a third order active low-pass filter. A prototype of this link has been fabricated and tested. The test results show that the transmission bandwidth of the analog signals is DC ∼ 155 MHz, the transmission delay is a typical 21 ns, the linear dynamic range is greater than 56 dB (692 times larger), the output noise is less than 4.5 mV, and the transmission distance is up to several kilometers, which can meet the requirements of ionizing radiation experiments. The FOL demonstrates great performance in transmission for scientific research with high quality in terms of transmission bandwidth, linearity, security, and stability.