Electric optical delay line is a device that adjusts the transmission path or speed of optical signals through electric field or motor control. It is mainly used to accurately control the delay time of optical signals and is widely used in fields such as optical communication, scientific research and testing. In precision optical applications such as Optical Coherence Tomography (OCT), Time Division Multiplexing (TDM), spectroscopic analysis, and interferometry, it is often necessary to calibrate signal synchronization or compensate for transmission delay by adjusting the optical path length or refractive index.
By driving the optical fiber or mirror with a motor to change the optical path length, or dynamically adjusting the delay time by regulating the refractive index of the optical fiber through an electric field. For example, a stepper motor drives optical components to translate on a guide rail, achieving micrometer level displacement accuracy; Electric field regulation affects the speed of light by changing the dielectric constant of the material.
Some electric optical delay lines adopt a structure combining precision mechanical design and electronic control technology, such as 64 channel electric optical delay lines, each channel is equipped with independent electric field control devices and fiber optic delay lines, which have the characteristics of high isolation, low crosstalk, compact and small size, making them easy to integrate and deploy.
Core principles and working mechanism
Fiber optic transmission characteristics
Optical signals propagate at speeds close to the speed of light in optical fibers, and their delay time is directly related to the length and refractive index of the fiber. For example, the delay time of a 1-kilometer fiber optic cable is about 5 microseconds (the speed of light is about 2 × 10 ⁸ meters/second).
Electro-optic effect regulation
Applying an electric field around electro-optic crystals such as lithium niobate can change their refractive index. When the electric field strength increases, the refractive index increases, the speed of light slows down, and the delay time prolongs; On the contrary, the delay time is shortened.
Mechanical micro displacement control
Using piezoelectric ceramics (PZT) or stepper motors to drive micro deformation of fiber optic coils, picosecond level delay is achieved by changing the optical path length.
Application scenarios
Optical communication system: Compensate for transmission delay in fiber optic links to ensure data frame alignment.
Scientific research testing: calibration of optical instruments, analysis of transmitter reflection effects, etc.
Precision measurement: used for fiber optic fault location in optical time domain reflectometry (OTDR).
Electronic Warfare and Radar Systems: Signal phase modulation or all-optical storage is achieved through delay lines.