40G QSFP+ SR4 Transceiver

The 40G QSFP+ SR4 transceiver is the fully specified 40G line in this catalogue. Its published specification sheet states a 40Gb/s rate, an 850nm wavelength, reach options of 100m and 300m over multimode fiber, power consumption below 3.5W and an operating temperature range of 0 to 70 degrees Celsius. The published models are BT-QSFP+-SR4 and BT-QSFP+-CSR4, with the 300m reach option belonging to the CSR4 model. The standards named on the product page are QSFP+ MSA and IEEE 802.3ba, with the interface designated 40GBASE-SR4. Those figures belong to this product alone and are not shared with any other transceiver on this site.

The 850nm wavelength places this module squarely in the multimode family, and that is the first thing a buyer should check. Multimode fiber is the standard medium inside buildings and across data-centre floors, where links are short and the fiber plant is built for it. A multimode module will not run over a single-mode plant, and a single-mode module will not run over a multimode plant, so the fiber type already installed decides the family before any other figure is considered. If the plant is multimode and the link is within a building or a campus floor, this module family is the natural shape for a 40G connection.

The two reach options deserve attention because they belong to different models. The standard model covers 100m over multimode fiber with an MPO connector, which suits the great majority of in-building links: switch to switch within a row, row to row within a hall, or floor to floor within a building. The CSR4 model extends that reach to 300m, which covers longer in-building runs, such as between halls or between floors in a larger building. A buyer should state the actual link length during the inquiry and confirm which model covers it, rather than assuming the longer reach applies to both models.

Power consumption below 3.5W and an operating range of 0 to 70 degrees Celsius govern the thermal side of the installation. Forty-gigabit modules run warm, and a densely populated switch needs a cooling budget worked out in advance. The published ceiling lets a buyer do that arithmetic before ordering. The temperature range covers ordinary indoor installations, and a buyer planning an installation outside that range should raise it during the inquiry.

The MPO connector is part of the design rather than an accessory choice. A 40G SR4 module sends four lanes in parallel over a multi-fiber connector, and the MPO connector is what carries those lanes in a single plug. That construction is also what makes the module practical at density: one port, one connector, 40G. Buyers moving from 10G SFP+ links to 40G should check that the fiber plant and the patch panels support MPO connections, or plan the conversion as part of the project, because a 40G SR4 module cannot be plugged into a duplex LC plant without a conversion strategy.

On certification, the product page for this model states RoHS compliant, together with standard compliance statements for the interface. Those statements are reported here as product-page statements, not as certificates reproduced on this site. Certificates are available upon request. No prices, minimum order quantities, delivery times or stock figures are stated for this model, because none have been published. Before ordering, confirm quantity, price and delivery time during the inquiry, together with the link length and the model that covers it.