Fiber optic delay refers to the component or device used to delay electrical signals for a certain period of time, which is called a fiber optic delay line. In recent years, with the rapid development of the electronics industry, such components have been widely used in precision oscilloscopes, color televisions, electronic computers, industrial process control, modern radar systems, and other fields.

The component or device used to delay electrical signals for a period of time is called a fiber optic delay line. Fiber optic delay lines should have flat amplitude frequency characteristics and certain phase shift characteristics (or delay frequency characteristics) within the passband, with appropriate matching impedance and minimal attenuation. For analog signals, inductors and capacitors are generally used, or coaxial cables and spiral wires are directly used; Digital signals also use charge coupled devices or surface acoustic wave devices.

Fiber optic delay lines are widely used in radar, electronic computers, color television systems, communication systems, and measuring instruments such as oscilloscopes.

Fiber optic delay lines are mainly divided into two categories: electromagnetic delay lines and ultrasonic delay lines. The delay of electromagnetic delay lines ranges from a few nanoseconds to tens of microseconds, and the amplitude frequency characteristics are mostly low-pass. When the delay is above a few microseconds, the bandwidth of 3 decibels is below several megahertz. The delay of ultrasonic delay lines ranges from a few microseconds to several thousand microseconds, with a bandpass amplitude frequency characteristic and a center frequency of several hundred megahertz or higher.

Fiber optic delay lines are widely used in precision oscilloscopes, color televisions, electronic computers, industrial process control, modern radar systems, and other fields. Common types of fiber optic delay lines include coaxial cable delay lines, ultrasonic delay lines, fiber optic/optical waveguide delay lines, etc.

In response to the high-precision requirements of fiber optic delay lines, a topology structure of fiber optic delay lines was designed based on optical switches and fibers. The impact of fiber optic connection errors and switch errors on the accuracy of delay lines was analyzed, and a method for reducing switch state errors was proposed in this paper. InCalculate all possible topological structures and their corresponding error values in Matlab environment. Select the topology structure corresponding to the minimum error value by setting conditions, and use it for the design of high-precision fiber delay lines. Simulation results have shown that using an optimized topology, the delay error is better than 2 ps when the switching error is less than 1 ps. A 5-bit fiber delay line was constructed using a magneto optic switch and single-mode fiber, and experimental results showed that the error is better than 2.98 ps when the step size is 100 ps.

Sichuan Ziguan Optoelectronics Technology Co., Ltd. has designed a new high-precision laser radar and quantum communication system that meets the requirements of laser radar and quantum communication0.5fs）， Low insertion loss（0.8db@330ps， 1.2db@750ps ，1.4db@1500ps ，1.8db@2000psA small-sized fiber optic delay line. Add main features on the basis of the original delay line function:

1. It has 1fs positioning function;

2. It has real-time temperature compensation delay function;

3. It has real-time delay stability compensation function;

4.Equipped with high-speed response function;

5. Equipped with optical power balancing function

6. Equipped with optical gain amplification function;

7. Channel insertion loss consistency function;

8. It has a portable function and can be controlled without communication with a microcontroller. This function is suitable for laboratory and laboratory applications.

9. Equipped with FPGA communication function, the communication speed can reach 10G, making it convenient for optical communication topology applications.

10. Rich communication interfaces, including RS232 422 485 R45, IIC I2C, etc., can achieve serial and parallel communication.

Sichuan Ziguan Optoelectronics can produce the following specifications of delay lines:

Single channel,8-channel, 32 channel, 1024 channel, single-mode, polarization maintaining, etc., and have achieved high integration with passive components such as WDM, EDFA, VOA, Optic silicon, etc., all of which have achieved the above functions.