CN

QSFP-40G-CWDM4 VS QSFP-40G-PSM4 Solution Comparison

Time: 2023-12-07
        The 40G QSFP+ LR optical module family includes two mainstream types: QSFP-40G-CWDM4 and QSFP-40G-PSM4.
        The former uses WDM technology for transmission over a single fiber, while the latter uses multiple parallel fibers.
1. QSFP-40G-CWDM4
        CWDM (Coarse Wavelength Division Multiplexing) allows multiple signals at different wavelengths to be transmitted simultaneously over one single fiber.
        QSFP-40G-CWDM4 uses duplex LC interfaces.
        At the transmit end, four typical wavelengths (1271 nm, 1291 nm, 1311 nm, and 1331 nm) are combined into one optical path by the built-in MUX, then transmitted to the remote end via LC fiber.
        At the receive end, the multiplexed optical signal is split back into four separate 10G channels by the DEMUX, as shown below:
QSFP-40G-CWDM4 signaling diagram
Figure 1 QSFP-40G-CWDM4 Signaling Diagram
2. QSFP-40G-PSM4
        PSM4 (Parallel Single Mode 4 lanes) transmits four independent channels over four separate single-mode fibers, with each signal carried on its own fiber.
        QSFP-40G-PSM4 uses an MPO interface.
        Inside the module, four independent 10G electrical signals are converted to optical signals and launched into four parallel fibers, with each fiber transmitting one 10G channel, as shown below:
QSFP-40G-CWDM4 signaling diagram
Figure 2 QSFP-40G-PSM4 Signaling Diagram
Application Comparison
        From a practical deployment perspective:
        • QSFP-40G-PSM4 has a simpler internal structure and lower module cost, but requires MPO patch cords which are more expensive, especially for long-distance links.
        • QSFP-40G-CWDM4 has a relatively higher module cost, but uses standard duplex LC patch cords at much lower expense, making it more suitable for long-distance cabling.
        Customers should choose the appropriate solution based on actual transmission requirements and on-site conditions.
        Moduletek Limited is at your service!
        For further inquiries about the above content, please contact us at: sales@moduletek.com
Back
PREVIOUS：Cisco ONS 15454 M2 Device Software Version Switching Procedure
NEXT：An Introduction To The Differences Between Singlemode And Multimode Fiber Optics