How to distinguish between multimode and singlemode Transceiver?

These day some clients want to know about the difference between multimode and single mode Transceiver, so we summarize some information about multimode and single-mode.

The difference between single mode and multimode of optical modules of different manufacturers is not the same, but in general, single mode optical modules and multimode optical modules are clearly distinguished.

1. What is a single mode optical module and a multimode optical module?
The single-mode (SM) optical module has small limitations and is suitable for long-distance data transmission. The multi-mode (MM) optical module can transmit multiple modes of light and is suitable for short-distance transmission. The single mode and multimode in the optical module actually refer to the type of optical fiber connected to the optical module.

2. The difference between single mode optical module and multimode optical module

(1) different wavelengths
The operating wavelength of a multimode optical module is generally 850 nm, and the operating wavelength of a single mode optical module is generally 1310 nm and 1550 nm.

(2) Different transmission distances
Single-mode optical modules are often used for long-distance transmission with transmission distances of up to 150 to 200 km. Multimode optical modules are mostly used for short-distance transmission, and multi-mode optical modules can be used with transmission distances of less than 2 km.

(3) Different fiber types
According to the transmission mode of the optical module in the optical fiber, the optical fiber can be classified into a single mode fiber and a multimode fiber. Multimode fiber (MMF) fiber diameter is generally 50/125μm or 62.5/125μm, single mode fiber (SMF) fiber diameter is 9/125μm

(4) different light sources
The light source of the single mode optical module is an LD or a narrow spectral line LED, and the light source of the multimode optical module is a light emitting diode or a laser.

(5) Different application scope
Single-mode optical modules are often used in transmission lines with relatively high transmission distances, such as metropolitan area networks.
Multi-mode optical modules are mostly used for short-distance transmission, and the transmission of network nodes and connectors is also very suitable for multi-mode optical modules.
In addition, multimode devices can only operate efficiently on multimode fibers, while singlemode devices can operate on both single-mode and multimode fibers, but single-mode devices do not guarantee results on multimode fibers.

(6) Different prices
Although single-mode fiber is cheaper than multimode fiber, single-mode optical modules are much higher than multimode optical modules.

3. Precautions for using single mode optical modules and multimode optical modules
(1) When using a single-mode optical module, ensure that the actual received optical power is less than the overload optical power, so the optical power is measured in combination with the optical power, and then selectively used with the optical attenuator.
(2) When using a single-mode optical module, there is a margin for receiving power.
(3) Multimode optical modules can only transmit signals of one wavelength and cannot be used with multiplexers.
(4) Multimode optical modules are limited to running on multimode fiber

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