40G QSFP+ CSR4 Optical Transceiver Module
Product Overview
The Apex 40G QSFP+ CSR4 module is the extended reach multimode member of the 40G family. Where a standard 40GBASE-SR4 part is specified to 100m on OM3, the CSR4 grade is characterised to 300m on OM3 and 400m on OM4, which is the difference between covering a row and covering the whole hall.
CSR4 exists because real cable runs are longer than a design document assumes. Once a link crosses a patch panel, a distributor frame or a maintenance loop of slack, a 100m graded link can be marginal in the middle of the day. The extended reach grade keeps the same MPO cabling and the same 850nm multimode optics but with tighter specification and testing.
Every unit is burnt in and tested for optical power, extinction ratio and error rate, supports DDM and is coded for the host platform you name. It drops into any 40G QSFP+ port that accepts a 40GBASE-SR4 module. Where the run has to leave the building, the LR4, ER4, PSM4 and BiDi grades from the same line take over on single mode fiber.
Key Features
- 40Gbps aggregated line rate compliant with 40GBASE-CSR4
- 850nm VCSEL array transmitter with PIN receiver array
- 300m over OM3 and 400m over OM4 multimode fiber
- MPO/MTP interface with 8 or 12 fiber connector options
- Drop in replacement for a 40GBASE-SR4 module in the same port
- Digital Diagnostic Monitoring (DDM/DOM) per lane with live optical readings
- Breakout to 4 x 10G available with the matching MPO to LC harness
- RoHS compliant, coded for your platform, held in stock for same day quoting
Technical Specifications
| Specification | Detail |
|---|
| Part Number | APX-QSFP-40G-300M-CSR4 |
| Manufacturer | Apex |
| Data Rate | 40Gbps (4 x 10Gbps lanes) |
| Form Factor | QSFP+, hot pluggable |
| Standard | 40GBASE-CSR4, backward compatible with 40GBASE-SR4 |
| Wavelength | 850nm |
| Maximum Reach | 300m OM3, 400m OM4, 100m OM2 |
| Fiber Type | Multimode Fiber (MMF) |
| Connector Type | MPO/MTP, 8 or 12 fiber |
| Transmitter | 850nm VCSEL array |
| Receiver | PIN photodiode array |
| DDM / DOM | Supported, per lane |
| Compliance | QSFP+ MSA, IEEE 802.3ba, RoHS |
| Temperature | 0 to 70C commercial, -40 to 85C industrial on request |
Applications
Hall Wide Multimode Links
Covers runs that exceed the 100m SR4 budget once patch panels, distributors and slack loops are counted.
Row to Row and End of Row
Connects top of rack switches to end of row or spine ports at 40G on the installed OM3 or OM4 cabling.
40G to 4 x 10G Breakout
Feeds four 10G server ports from one 40G switch port with an MPO to LC harness, using the extended reach headroom.
Compatibility
40G CSR4 modules are coded to the host platform you specify, including 40G switches, routers and server adapters, and are tested on live ports before shipment. A CSR4 module is accepted by ports that take 40GBASE-SR4, so no software change is needed; the practical decision is the fiber grade and the measured loss. Send the cable type, the route length and any patch panel counts and we confirm whether SR4 or CSR4 is the right grade for each link.
Related Products
Frequently Asked Questions
What is the difference between 40G SR4 and CSR4?
Both use the same 850nm multimode optics and MPO connector. SR4 is specified to 100m on OM3, CSR4 is characterised to 300m on OM3 and 400m on OM4, so CSR4 suits longer in-hall runs.
Will a CSR4 module work in a port that expects SR4?
Yes. CSR4 is a drop in replacement for a 40GBASE-SR4 port, and the link comes up at the same 40G speed with no configuration change.
Do I need CSR4 or single mode for a 500m link?
Beyond the multimode limits, move to single mode: 40G PSM4 or LR4 modules cover 2km to 10km on single mode fiber. Tell us the span and we confirm which grade closes the link with margin.
Are 40G CSR4 modules in stock?
Yes. The 850nm CSR4 grade is held in stock and quoted the same day, together with MPO to LC harnesses for breakout applications.
Why Choose Apex
- Optical engineering support and supply from 1.25G to 800G, including the full 40G QSFP+ range.
- Link budget checked against the real route length before the grade is confirmed.
- Every module is tested for optical power, extinction ratio and error rate before shipment.
- Backed by a 3 year warranty and technical support before and after the sale.
