According to the mode, the optical module can be divided into multi-mode optical module and single-mode optical module. The multi-mode optical module is generally coarse and can transmit a variety of modes of light. Due to the large inter-mode dispersion, the transmission frequency of digital signal is limited.
Define
The optical device used in the optical module is matched with the multimode optical fiber to obtain the best transmission characteristics. The optical module is called multimode optical module. The center glass core of the multimode fiber is relatively thick (50 or 62.5 m), which can transmit a variety of light modes. The large dispersion limits the frequency of digital signal transmission, thus affecting the transmission distance of the multimode optical module. Multimode optical modules are usually marked "MM".
Feature
1. The wavelength is generally 850 and 1300nm;
2. Short transmission range, usually 300m -- 500m;
3. Pull ring or the outside color is black;
4. It can be applied to HDMI optical terminal and SDI optical terminal.
The difference between multimode optical module and single-mode optical module
1, the size of single-mode optical module optical fiber is 9-10/125 m, almost all the multi-mode optical fiber size are 50/125 m or 62.5/125 m, the multi-mode optical module bandwidth (information transmission capacity of optical fiber) is usually 200MHz to 2GHz. The single-mode optical module has infinite bandwidth and lower loss.
2. The multi-mode optical module can carry out transmission as long as 5 kilometers through multi-mode optical fiber. The single-mode optical module is mostly used for long-distance transmission, sometimes up to 150 to 200 kilometers;
3. The multi-mode optical module USES LED or laser as the light source, while the single-mode optical module USES LED with LD or narrow spectral line as the light source.
4. Multi-mode optical module ring pulling or the external color is black; Single mode optical module ring pull or external color is blue, yellow or purple;
5. The price of multi-mode optical module is cheap, but the single-mode optical module is much more expensive than the similar multi-mode optical module;
6. Single-mode optical module can operate on both single-mode optical fiber and multi-mode optical fiber, and the multi-mode optical module is limited to operate on multi-mode optical fiber.
Notes for the use of multimode optical module
1. The multimode optical module is transmitted by refraction, so two wavelengths cannot be transmitted in different directions on the optical fiber, and it is limited to operate on the multimode optical fiber;
2. The multi-mode optical module can only send a signal of one wavelength, which cannot be used in conjunction with the multiplexer;
3. Multi-mode optical module is applied in short distance transmission such as SR, such as internal transmission in the machine room.
