Vlink Application Engineering Note

4x25G PSM&CWDM 40G/100G Transceiver Module

-VLINK MT-Fiber Array and CWDM4 Block Series Products

WWW.VLINKOPTICS.COM

The traditional data center is mainly based on the 10G network architecture. In order to adapt to the scale deployment of AI, deep learning, big data computing and other services, the next-generation data center architecture is evolving to the 25G/100G network architecture. In China, Internet giants such as BAT have been realized Scale deployment.Building a 25G/100G data center requires a large number of 100G optical transceiver modules, which account for a relatively high proportion of network construction costs. What are the 100G optical module standards? How do we choose? Today, we will briefly introduce the most common QSFP28+ PSM4 and QSFP28+ CWDM4 package form for data center 100G optical modules.

1. What is the QSFP28 PSM4 optical module?

The QSFP28PSM4 optical module is a high speed and low power product specifically designed for optical interconnects in data communications applications. It complies with the PSM4MSA optical interface specification, has a hot-swappable QSFP form factor, and built-in digital diagnostics. It has four independent full-duplex channels with a data rate of 25.78 Gb/ps per channel. The QSFP28+ PSM4 optical module is mainly used in 40G and 100G Ethernet. The high bandwidth module supports 100GbE optical links through single mode fiber. The following figure shows the working principle of the PSM4 QSFP 28 optical module in 100G Ethernet.

2. What is the QSFP28+ CWDM4 optical module?

Vlink Application Engineering Note

The transmission rate of the QSFP28+ CWDM4 optical module is 103.1Gbp, which is mainly used in computing, high-frequency trading and other fields. Its cost is significantly higher than that of the QSFP28PSM4 optical module. Through coarse wavelength division multiplexing (CWDM) technology, the QSFP28+ CWDM4 optical module multiplexes four wavelengths of 1270nm, 1290nm, 1310nm and 1330nm onto a single mode fiber for transmission. The following figure shows the working principle of the CWDM4 QSFP28+ optical module in 100G Ethernet.

3. PSM4 vs. CWDM4

Because of the use of wavelength division multiplexer, the optical module cost of CWDM4 is higher than that of PSM4 optical module. However, CWDM4 requires only two single-mode fibers in two-way transmission, which is much less than the eight single-mode fibers of PSM4. The total cost of the PSM4 program has risen very quickly. In applications, it is necessary to decide whether to use PSM4 or CWDM4 depending on the interconnection distance.

PSM 4 Module CWDM4 Module

LD4 Silicon-integrated modulator

and 1 DBR Laser4 CWDM laser

CWDM devices No need 4-Ch CWDM

Connector MPO LC Connector

Fiber Channel 8 Channel 2 Channel

Distance 500m 2000m

Vlink Application Engineering Note

4. VLINK is committed to providing optical connectivity solutions to the world's top optical module customers

5. VLINK’s Capability on FA for different packages solutions of high speed modules

5.1. All Types of Fiber ArrayVLINK’s can provide all types fiber array used on traditional PSM4 QSFP+ 28 package such as 45degree polish fiber array with/without fiber protrusion, 90 degree fiber bending fiber array for silicon photonics grating package, MFD matching PM fiber/ single mode fiber array for silicon photonics edge coupling, 5ch/1ch fiber array to receptacle for PLC AWG assembly.

The Quad Small Form-Factor Pluggable (QSFP) Parallel Single-Mode (PSM) Optical transceiver is a highly integrated 4-channel optical module that provides increased port density and total system cost savings.

Vlink’s 4ch/ 5ch FA subassembly with LC stubs and LC receptacle is ideal for AWG alignment. High FA pitch accuracy and polishing angle can make alignment easy.

Vlink’s Thin Film Filter CWDM and LAN WDM block is with small size, high effective aperture, low pointing angle, suited for QSFP28 transceiver modules.

Vlink Application Engineering Note

5.2. High Accuracy Core PitchVLINK’s high precision fiber array can achieve typical Core Pitch error <0.5um by controlling the V Groove material and process.VLINK has equipped with YAGISHITAGIKEN YGN-590-FAVGMT, which has the capability to measure the core of fiber array with very high accuracy.

5.3. Control Fiber Array Surface With difference process, fiber height is controlled to meet customer’s different application. Fiber height change is controlled by aging process.

5.4. Meet High Temperature RequirementDuring the different bonding process of the transceiver module, the operating temperate is different. In some case the temperate is high up to 150degree or more which require the fiber array can support the high temperature. VLINK can provide

Fiber

V Groove Base

Vlink Application Engineering Note

customer special fiber array with high Tg bonding Epoxy to meet different temperature application

5.5. Enhanced Anti-Pull TestWith improved process, VINK’s fiber array have very good anti-pull performance. It can pass side pull test at high temperature conditions with load.

5.6. Mass production capability with high efficiencyVLINK allocates 10% resource on new product design and improving the yield and efficiency of mass production products. The in-house designed fixture/tools make the production have high yield and efficiency. VLINK has delivered half million fiber array related parts in 2018.

6. Summary VLINK is one of the key suppliers on 40G/100G SR4 and PSM4 jumper and

CWDM4 TFF/AWG subassembly on high speed module VLINK owns 9 patents focusing on high PER PM devices for Coherent

communication and special Fiber Array for Silicon Photonics transceiver modules VLINK allocates over 10% R&D resources giving fast response to new product

design and support cost reduction VLINK’s volume production experience to support cost effective and capacity

ramp up fast VLINK’s capability of packing, assembly, epoxy control and PER measurement

on PM devices can provide customer competitive products

7. About VLINK Optics Corporation

VLINK Optics is a high technology company focusing on developing, manufacturing and selling silicon photonics fiber connectivity and micro/short fiber jumper used on 40G, 100G and 400G high speed transceiver modules, including SR4 MT-MT jumper, PSM4 MT-FA jumper, MT-FA for grating coupling or edge coupling of silicon photonics package, TFF CWDM4/LAN WDM or PLC CWDM4/LAN WDM subassembly High PER Polarization-Maintaining devices

VLINK keep integrating advanced technologies and resources, trying to be an innovator and explorer on the field of fiber optics micro connection on high speed modules. VLINK provide customer fiber optics micro-connection solutions of inter-connecting in high speed modules with compact size, low power consumption, cost effective and quality guarantee.