Have you ever encountered the problem that the link cannot beup when the 1310nm optical module is transmitted on G.655 optical fiber? I encountered this kind of problem recently, and now I want to share it with you.
2.Use G.652 optical fiber test in lab, Link works ok. Optical module Tx power and Rx power are in spec. That means optical transceivers performance are ok.
3.DWDM optical modules work well on G.655 link，that means G.655 link no break.
4.Deduce：The optical module wavelength and fiber type don’t match
Root Cause:
Optical modules with a working wavelength of 1310nm cannot use G.655 optical fiber for long-distance transmission, G.655 Optical cable cutoff wavelength ≤ 1480nm, work window is C band and L band (1530nm~1625nm) , which means if wavelength smaller than 1480nm，cannot use on G.655
Summary:
1. G.655 optical fiber cannot transmit 1310 nm signals because the cut-off wavelength of G.655 optical fiber is 1480 nm.
2. If the input power and receive power are normal but the link cannot be up, it is usually because the optical module type does not match the fiber type.
all 800G modules make use of 8x electrical lanes in both directions, comprising 8 transmit lanes and 8 receive lanes. Each lane operates at a data rate of 100G PAM4, resulting in a total module bandwidth of 800Gb/s. Additionally, the optical output of all 800G transceivers comprises 8 optical waves, with each wave modulated at 100G PAM4 per lane.
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HTF can help you design coherent 400G/200G/100G DWDM/OTN solution, DWDM Single lamda support 100G/200G/400G Dual fiber/Single fiber Ultra long distance transmission. Expand your network capacity and DCI network easily.
No. The OSFP and the QSFP-DD are two physically distinct form factors. For OSFP systems, OSFP optics and cables must be used, and for QSFP-DD systems, QSFP-DD optics and cables must be used.
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HTF can help you expand the network capacity by DWDM solution.
HTF can help you design coherent 400G/200G/100G DWDM/OTN solution, DWDM Single lamda support 100G/200G/400G Dual fiber/Single fiber Ultra long distance transmission. Expand your network capacity and DCI network easily.
Amidst the high-speed optical module landscape, the incorporation of DSP chips for signal processing has been the norm. These chips, featuring ADC/DAC, FEC, retiming, reshaping, adaptive equalization, and more, hold immense power, yet their potency comes at the cost of significant power consumption and expenses. A typical 7nm DSP in a 400G optical module consumes around 4W, constituting 50% of the module’s power consumption.
DSP Function Block Diagram
The following figure shows the power consumption breakdown of a 400G ZR optical module, with a similar scenario for an IMDD.
As a response to the need for efficiency, the revolutionary concept of Linear-drive technology emerged.
How can the power consumption and cost impact caused by DSP be mitigated?
By forgoing DSP within the optical module and integrating its functions into switching chips, a streamlined design emerges. The result? A compact configuration housing only driver and TIA components. Diverging from the traditional driver and TIA functions, those in the Linear Photonic Optics (LPO) architecture include CTLE and Equalization features, facilitating signal compensation. Notably, the Linear Drive concept obviates the need for retiming, eliminating non-linear processes and thus dubbed the Non-retimed module.
LPO’s merits encompass several facets:
Low Power Consumption: LPO yields a 50% reduction in power consumption compared to pluggable optical modules, aligning closely with CPO power levels.
The overall power consumption of the switch system will be reduced by about 25 percent, as below.
Low Latency: Omitting DSP significantly reduces system latency, ideal for latency-sensitive scenarios like inter-GPU communication within High-Performance Computing (HPC) centers.
Cost Efficiency: The absence of 5nm/7nm DSP chips translates to cost savings. In an 800G module, the Bill of Materials (BOM) cost totals around $600-$700, with DSP chips accounting for approximately $50-$70. While EQ integration within Driver and TIA adds $3-$5, the total system cost reduction amounts to around 8%.
Hot-Pluggability: LPO retains the convenience and reliability of pluggable modules, leveraging established optical module supply chains. This distinguishes LPO from CPO, which is still less widely adopted due to reliability and cost considerations.
Comparison of various dimensions of conventional optical modules, LPOs and CPOs
In summary, LPO represents a novel approach with its unique advantages and ongoing challenges.
Integration of DSP Chips: To implement LPO, there’s a need to integrate DSP chips into switches, which requires the involvement of switch chip manufacturers. The LPO concept has also stirred the competition among DSP chip manufacturers, such as Broadcom and Inphi.
New Protocols and Testing Methods: Introducing LPO necessitates the development of new protocols and testing methods. The Optical Internetworking Forum (OIF) is currently working on defining the CEI-112G-LINEAR standard to address this need.
Applicability and Distance: One concern is whether LPO is suitable for longer distances, potentially reaching kilometers. As DSP chips are no longer present in the module, there may be a decrease in error performance, leading to a reduction in transmission distance.
While several companies showcased their linear-drive solutions, particularly during OFC 2023, and launched LPO options post-event, the transition from technical discussions to widespread adoption is ongoing. The introduction of LPO underscores the industry’s pursuit of low-power, low-cost, high-speed optical modules.
Point-to-point network, chain network, ring network, mesh network
Point-to-point line:referred to as P2P or PTP. Point-to-point transmission refers to the transmission of services between two points (data centers). Generally, it is optical transmission over a relatively short distance within 100 kilometers.
Chain network: There are one or more sites with business up and down between point-to-point transmission.
Ring network: all business sites form a ring network
Mesh network: transmission line composed of multiple interwoven ring networks.
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1.6T OSFP-XD DR8+ is designed to transmit and receive serial optical data links up to 212.5 Gb/s data rate (per channel) by PAM4 modulation format over single-mode fiber. It is a small-form- factor hot pluggable transceiver module integrated with high performance EML laser. It is compliant with 1600G Ethernet specs and OSFP-XD MSA.
1.6T OSFP-XD 2*FR4 is designed to transmit and receive serial optical data links up to 212.5 Gb/s data rate (per channel) by PAM4 modulation format over single-mode fiber. It is a small-form- factor hot pluggable transceiver module integrated with high performance EML laser. It is compliant with 1600G Ethernet specs and OSFP-XD MSA.
What are the packaging methods of 400G optical modules?
400G optical modules are mainly divided into CDFP, CFP8, QSFP-DD, and OSFP according to packaging methods. CDFP and CFP8 are larger in size and have higher thermal capacity and are mainly used in the telecommunications market.
QSFP-DD is forward compatible with the previous QSFP-28, with the smallest size and higher density. QSFP-DD is more suitable for use in short-distance data centers. QSFP-DD has many supporters including Facebook, Alibaba, Tencent and other companies. Supporters of OSFP MSA include Google and Arista. The size of OSFP is slightly larger than that of QSFP-DD. The QSFP-28 optical module needs to add an adapter to be compatible with the OSFP socket. OSFP can support 800G backwards. OSFP comes with a heat sink and can support With 12w-15w thermal capacity, OSFP is more suitable for the telecommunications market.
designed to transmit and receive serial optical data links up to 106.25 Gbps data rate (per channel) by PAM4 modulation format over single-mode fiber. It is a small-form-factor hot pluggable transceiver module integrated with high performance EML laser. It is compliant with 800G Ethernet specs and QSFP-DD MSA.
Features
Up to 106.25Gbps data rate per channel by PAM4 modulation
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