100G Optical Module Selection

QSFP28 is the primary form factor for 100G optical modules, supporting multiple types such as SR4, LR4, CWDM4, ER4, and PSM4 for different distances and applications.Overview of 100G Optical Modules100G optical modules are hot-pluggable transceivers that convert electrical signals into optical signals and vice versa, enabling high-speed data transmission at 100 Gbps. The QSFP28 (Quad Small Form-factor Pluggable 28) is the most widely used form factor, featuring four parallel 25 Gbps lanes aggregated to achieve 100 Gbps throughput. QSFP28 modules are valued for high port density, low power consumption (typically 3–5 W per port), and compact size, making them ideal for data centers, enterprise networks, and telecom infrastructure .Common 100G QSFP28 Module TypesQSFP28-100G-SR4: Designed for short-range multimode fiber transmission, typically within data centers. It uses four parallel channels over a 12-core multimode ribbon fiber, supporting distances up to 100 meters on OM4 fiber. Ideal for intra-data center links and storage area networks (SANs), .QSFP28-100G-LR4: Supports long-range single-mode fiber transmission, suitable for inter-data center connectivity and metropolitan area networks (MANs). It uses four wavelengths multiplexed over a single-mode fiber, extending reach up to 10 km or more .QSFP28-100G-CWDM4: Implements Coarse Wavelength Division Multiplexing (CWDM) to transmit four wavelengths (1270 nm, 1290 nm, 1310 nm, 1330 nm) over a single-mode fiber. This module optimizes spectral efficiency and is suitable for applications requiring higher capacity without additional fiber .QSFP28-100G-ER4: Engineered for ultra-long-distance transmission, spanning hundreds of kilometers. It is used in inter-city links and regional networks, providing high signal integrity and reliability .QSFP28-100G-PSM4: Uses parallel single-mode fiber (PSM4) technology with four independent edge-emitting lasers, supporting high-density data center environments and ultra-high-speed connectivity over single-mode ribbon fiber .QSFP28 BIDI: A bidirectional WDM module that transmits and receives over a single strand of single-mode fiber using two wavelengths (e.g., 1270 nm/1330 nm), reducing fiber count and simplifying cabling. Reach can extend up to 10 km .Key Features and ConsiderationsTransmission Distance: Ranges from 100 meters (SR4) to hundreds of kilometers (ER4).Fiber Type: Multimode for short-range (SR4), single-mode for long-range (LR4, CWDM4, ER4, PSM4).Power Efficiency: Typically 3–5 W per module, helping reduce data center cooling costs.Port Density: QSFP28 modules provide four times the bandwidth of SFP28 in the same footprint, enabling high-density deployments.Monitoring: Many modules support Digital Diagnostic Monitoring (DDM) for real-time temperature, voltage, and optical power insights .Applications100G optical modules are widely deployed in:Data centers for high-speed intra- and inter-rack connectivity.Enterprise networks for core and distribution layers.Telecom networks for metro and long-haul links.High-performance computing environments requiring low-latency, high-bandwidth connections . These modules allow network operators to scale bandwidth efficiently, reduce cabling complexity, and maintain reliable high-speed optical links across diverse network topologies.