What is the range of a 155M optical module

The range of a 155M optical module varies from 15 km to 160 km depending on the module type and fiber used.Typical Transmission Distances155M SFP modules, designed for 155 Mbps (STM-1/OC-3) networks, have different ranges based on their design and application:Short to intermediate reach modules: Standard FP (Fabry-Perot) laser modules over single-mode fiber typically achieve up to 15–20 km . These are commonly used in metropolitan access networks or campus backbones.Extended reach modules: Some 155M SFPs are designed for 40 km, 80 km, or even 160 km transmission over single-mode fiber, often using higher-quality lasers or CWDM (Coarse Wavelength Division Multiplexing) technology . These are suitable for long-haul telecom links or utility networks.Wavelength considerations: Modules operating at 1310 nm are standard for intermediate distances, while 1550 nm modules are often used for longer distances due to lower fiber attenuation .Factors Affecting RangeFiber type: Single-mode fiber (SMF) supports longer distances than multi-mode fiber (MMF).Optical power and sensitivity: Modules with higher output power and more sensitive receivers can achieve longer distances.Network conditions: Splices, connectors, and fiber attenuation affect the practical range. The listed distances are typically calculated assuming standard fiber attenuation and minimal losses.Environmental conditions: Temperature and installation quality can slightly reduce effective range.SummaryFor a 155M SFP optical module, you can expect:Short/intermediate reach: 15–20 km over single-mode fiberMedium reach: 40–80 km with enhanced modulesLong reach: Up to 160 km with specialized CWDM or long-haul modulesSelecting the appropriate module depends on your network topology, fiber type, and required link distance .