Category: Fiber Transceivers

As a result of data center consolidation, server virtualization, and new applications that require higher data transport rates, 10Gbps infrastructure is becoming overwhelmed by today’s data center requirements, making the shift to 40 and 100 Gbps inevitable, especially in the network aggregation layer and core. How to upgrade the cabling infrastructure and migrate to the 40Gbps era in a cost-effective way? Cisco 40G QSFP (quad small form-factor pluggable) bidirectional (BiDi) technology provides a feasible and effective method, which will be introduced in the following text.

What Is 40G QSFP BiDi Transceiver?

c The Cisco BiDi transceiver supports link lengths of 100m and 150m on laser-optimized OM3 and OM4 multimode fibers. It complies with the QSFP MSA specification, enabling customers to use it on all QSFP 40 Gbps platforms to achieve high-density 40 Gigabit Ethernet networks.

How Does 40G QSFP BiDi Transceiver Work?

Cisco QSFP BiDi transceiver technology converts four channels each of 10Gbps transmit and receive signals to two bidirectional channels of 20Gbps signals, which means that the Cisco QSFP BiDi transceiver has two 20Gbps channels, each transmitted and received simultaneously over two wavelengths on a single MMF strand. The technology uses specialized, multilayer, thin-film dielectric coating and lensing, which allows components to both pass and reflect optical signals at the same time. And it uses Bidirectional Optical Sub-Assembly (BOSA) technology to support two wavelengths (20 Gbps total) on each fiber. The connection can reach 100 meters on OM3 MMF or 150 meters on OM4 MMF, which is the same as 40Gbps SR4. Picture below shows the technology concept of the Cisco QSFP BiDi transceiver.

Why Choose 40Gbps QSFP BiDi Transceiver?

The Cisco QSFP BiDi transceiver transmits full-duplex 40Gbps traffic over one dual-fiber LC connector OM3 or OM4 MMF cable. It provides the capability to reuse 10Gbps fiber infrastructure. In other words, it enables data center operators to upgrade to 40Gbps connectivity without making great changes to the previous 10Gbps fiber cable plant. By using the existing 10 Gigabit Ethernet duplex multi-mode fiber (MMF) infrastructure for 40 Gigabit Ethernet, the Cisco BiDi transceiver offers significant cost savings and simplifies data center upgrading. It allows for zero-cost fiber migration by reusing the current 10Gbps cabling for 40Gbps device connectivity. 40Gbps QSFP BiDi transceiver reduces overall costs and installation time for customers migrating data center aggregation links to 40Gbps connections. Using Cisco BiDi transceivers offers 75% less fiber and MPO requirements, reduced cable sprawl and rack footprints, and investment protection with future support for 100 Gbps over duplex fiber.

Conclusion

Cisco 40G QSFP BiDi technology removes 40Gbps cabling cost barriers for migration from 10Gbps to 40Gbps connectivity in data center networks. It is quite a competitive option among all those various choices for 40 Gigabit Ethernet applications, such as QSFP+ transceiver, QSFP+ breakout cable or active optical cable. Compared with them, Cisco 40G QSFP BiDi transceivers provide simpler and less expensive 40Gbps connectivity compared to other 40Gbps transceiver solutions. Anyway, you choose the most appropriate one for your applications.

In communication networks, many transmission lines need bidirectional transmission. This need leads to the development of Bidirectional (BiDi) transceivers, which can transmit and receive data to/from interconnected equipment through a single optical fiber. BiDi transceivers are fitted with wavelength division multiplexing (WDM) diplexers, which combine and separate data transmitted over a single fiber based on the wavelengths of the light. BiDi transceivers must be deployed in matched pairs, with their diplexers tuned to match the expected wavelength of the transmitter and receiver that they will be transmitting data from or to. In this post, a kind of BiDi transceiver, 1000BASE-BX SFP BiDi transceiver will be introduced.

Introduction

1000BASE-BX is a part of the Gigabit Ethernet standard related to transmission over fiber optic cable. 1000BASE-BX SFP modules are compliant with SFP Multi-Source Agreement (MSA) specification and SFF-8472, and conform to the IEEE 802.3ah 1000BASE-BX10 standard. 1000BASE-BX SFP modules include 1000BASE-BX-U SFP module and 1000BASE-BX-D SFP module. These two SFP modules must be used in pairs to permit a bidirectional Gigabit Ethernet connection using a single strand of single mode fiber (SMF) cable. These transceivers transmit and receive signals on one fiber strand using two wavelengths in each direction. These hot pluggable optical transceivers consist of two sections: the transmitter section uses 1490nm DFB laser/1310nm Fabry-Perot laser, and the receiver section uses 1310nm/1490nm receiver accordingly. The 1000BASE-BX-D SFP operates at wavelengths of 1490nm TX/1310nm RX, and the 1000BASE-BX-U SFP operates at wavelengths of 1310nm TX/1490nm RX. These transceivers use standard simplex LC connectors for fiber cable connection and provide a long transmission distance of up to 10 km.

Key Features

Data rate up to 1.25 Gbps

Hot-pluggable SFP footprint

1490 nm DFB Transmitter and 1310 nm PIN Receiver

1310 nm FP Transmitter and 1490 nm PIN Receiver

Transmission distance up to 10 km

Simplex LC connector

Low power dissipation

Digital diagnostic monitor interface is compliant with SFF-8472

Compliant with SFP MSA Specification

Compliant with IEEE 802.3z Gigabit Standard

RoHS compliance

1000BASE-BX-D SFP

1000BASE-BX-D SFP supports link length of up to 10km point to point on single mode fiber (1490nm-TX/1310nm-RX wavelength) at 1Gbps bidirectional. This optic uses an LC connector. The picture below show a Cisco GLC-BX-D compatible 1000BASE-BX-D SFP 1490nm-TX/1310nm-RX transceiver. The GLC-BX-D is a small form factor pluggable module for Gigabit Ethernet 1000BASE-BX and Fiber Channel communications. The GLC-BX-D transceiver operates at 1490Tx/1310Rx wavelength. It is compatible with the IEEE 802.3ah 1000BASE-BX10-D standards. A 1000BASE-BX-D device is always connected to a 1000BASE-BX-U device with a single strand of standard SMF.

1000BASE-BX-U SFP

1000BASE-BX-U SFP supports link length of up to 10km point to point on single mode fiber (1310nm-TX/1490nm-RX wavelength) at 1Gbps bidirectional. This optic uses an LC connector. The communication over a single strand of fiber is achieved by separating the transmission wavelength of the two devices. 1000BASE-BX-D transmits a 1490nm channel and receives a 1310nm signal, whereas 1000BASE-BX-U transmits at a 1310nm wavelength and receives a 1490nm signal. A wavelength-division multiplexing (WDM) splitter integrated into the SFP to split the 1310nm and 1490nm light paths. The GLC-BX-D and GLC-BX-U SFPs also support digital optical monitoring (DOM) functions according to the industry-standard SFF-8472 multisource agreement (MSA). This feature gives the end user the ability to monitor real-time parameters of the SFP, such as optical output power, optical input power, temperature and transceiver supply voltage. The picture below show a Cisco GLC-BX-U compatible 1000BASE-BX-U SFP 1310nm-TX/1490nm-RX transceiver.

Applications

Gigabit Ethernet

Fiber Channel Links

Switch to switch interface

Switched backplane applications

Pouter/Server Interface

Other optical transmission systems

Conclusion

New organizational applications, virtualization, and data center consolidation trends are pushing your server I/O requirements to meet higher needs than before. With new BiDi optical technology, SFP BiDi transceivers make it much easier for you to upgrade your networks.

As we know, fiber optic patch cords are capped at both ends with fiber optic connectors to allow them to be rapidly and conveniently connected to telecommunication equipment. Fiber optic connector is one of those high quality ceramic components used to achieve accurate and precise connections of the fiber ends. It is a simple device which allows fiber links to be readily connected and disconnected.

How to install fiber optic connectors to optical fibers so that they can achieve accurate and precise connections? The method for attaching fiber optic connectors to optical fibers varies based on connector types. Installation ways of fiber optic connectors largely depends on the connector types. Generally, connectors can be categorized into no-epoxy/no-polish connectors and epoxy-and-polish connectors. The following text elaborates on how to install these two kinds of connectors respectively.

No-epoxy/no-polish Connector Installation

How to install no-epoxy/no-polish (NENP) connectors to optical fibers? A no-epoxy/no-polish connector includes an precisely polished endface. When installing an NENP connector, there is no need to use an epoxy or to polish the endface. The field fiber is mechanically spliced to a factory-cleaved fiber stub. The following picture is an illustration of  no-epoxy/no-polish connector installation.

The installation process begins with preparing the field fiber, which is done by stripping the protective coating down to the bare glass. Once the fiber is cleaned, it is then cleaved with a precision cleaver. Next step is to insert the field fiber into the connector until it is seated against the factory-stubbed fiber and locked into place mechanically by a rotating cam or other means. Typically this step is achieved by using a tool that holds the connector and activates the mechanical splice by a button or lever.

Epoxy-and-polish Connector Installation

How to install epoxy-and-polish (EP) connectors to optical fibers? The most common types of EP connectors use heat- or anaerobic-curing techniques. A heat-cure connector uses heat to harden an epoxy, which takes several minutes. An anaerobic EP connector uses a two-part epoxy, a hardener that is inserted into the connector and an activator on the fiber.

To install an EP connector, an epoxy must be inserted into the connector ferrule first to form a bond between the field fiber and the connector’s ferrule, and then the endface needs to be hand-polished. Next, the field fiber is stripped down to the bare glass and cleaned. If the connector is heat-cure, the fiber is inserted into the connector and placed in an oven for the epoxy to cure. If the type of connector is anaerobic, the bare fiber is painted with an activator and inserted into the connector. Once the epoxy has been cured, the fiber stub which is protruding above the ferrule is scribed and removed. The final step is to polish the endface of the connector using a fixture and several different polishing films.

Notes for Fiber Optic Connector Installation

Besides different installation methods for different connector types, several things need to be paid attention to when installing fiber optic connectors, especially when a fiber patch cord has two different types of connectors, such as LC-SC fiber optic patch cord or FC-ST fiber optic patch cord.

• The bared fiber must be thoroughly cleaned with fiber optic cleaning fluid. Never clean the fiber with a dry tissue. Before the connection is made, the end of each fiber must have a smooth finish that is free of defects such as hackles, lips, and fractures.

• The cable should be cut about one inch longer than the required finished length.

• Be sure to use strippers made specifically for use with fiber rather than metal wire strippers because damage can occur and then weaken the fiber.

Any problems with a connector, such as poor installation and uncleanness, can greatly influence the transmission and reception of the light power. And such problems may render the fiber optic system inoperative. So it is very necessary to know something about installation of fiber optic connectors

Fiber Optic Connector Selection

Connector is an integral component of the cabling system infrastructure, which keeps the information flowing from cable to cable or cable to device. There are various connector types, including LC, FC, ST, SC, MTRJ, MPO, MTP, DIN, E2000, MU, etc. To design a fiber optic system, optical connector selection is also a very important decision. When selecting an optical connector, you have to take fiber types, polishing styles and number of fibers all into consideration.

Polishing Styles: There are mainly three kinds of polishing styles, PC (physical contact), APC (angled physical contact), and UPC (ultra physical contact). PC, UPC and APC refer to how the ferrule of the fiber optic connectors is polished. PC connector is used in many applications. UPC connectors are often used in digital, CATV, and telephony systems. APC connectors are preferred for CATV and analog systems. The picture below shows these three kinds of polishing styles.

Fiber Types: Single-mode and multi-mode optical fiber are two commonly used fiber types. Accordingly, there are single-mode optical connector and multi-mode optical connector. ST and MTRJ are the popular connectors for multi-mode networks. LC connector and SC connector are widely used in single-mode systems. Single-mode fiber optic connectors can be with PC, or UPC or APC polish, while multi-mode fiber optic connectors only with PC or UPC polish.

Number of Fibers: Simplex connector means only one fiber is terminated in the connector. Simplex connectors include FC, ST, SC, LC, MU and SMA. Duplex connector means two fibers are terminated in the connector. Duplex connectors include SC, LC, MU and MTRJ. Multiple fiber connector means more than two fibers (for up to 24 fiber) are terminated in the connector. These are usually ribbon fibers with fiber count of 4, 6, 8, 12 and 24. The most popular ribbon fiber connector is MT connector.

Conclusion

The key to designing a successful fiber optic system is understanding the performance and applications of different kinds of fibers, cable constructions and optical connectors, and then utilizing the appropriate components. fiber-mart.com provides a wide range of fiber optic cables and connectors. Fiber optic cables can be available in single-mode, multimode, or polarization maintaining, and they can meet the strength and flexibility required for today’s fiber interconnect applications.

Proper selection of fiber optic cables and connectors for specific uses is becoming more and more important as fiber optic systems become the transmission medium for communications and aircraft applications, and even antenna links. Choices must be made in selecting fiber optic cables and connectors for high-reliability applications. This article provides the knowledge for how to make appropriate selections of fiber optic cable and connector when designing a fiber optic system.

Fiber Optic Cable Selection

To select a fiber optic cable, you have to make choices of both the fiber selection and the cable construction selection.

Fiber Selection

The three major fiber parameters used in selecting the proper fiber for an application are bandwidth, attenuation and core diameter.

Bandwidth: The bandwidth at a specified wavelength represents the highest sinusoidal light modulation frequency that can be transmitted through a length of fiber with an optical signal power loss equal to 50 percent of the zero modulation frequency component. The bandwidth is expressed in megahertz over a kilometer length (MHz/km).

Attenuation: The optical attenuation denotes the amount of optical power lost due to absorption and scattering of optical radiation at a specified wavelength in a length of fiber. It is expressed as an attenuation in decibels of optical power per kilometer (dB/km). The attenuation is determined by launching a narrow spectral band of light into the full length of fiber and measuring the transmitted intensity.

Core Diameter: The fiber core is the central region of an optical fiber whose refractive index is higher than that of the fiber cladding. Various core diameters are available to permit the most efficient coupling of light from commercially available light sources, such as laser diodes. There are two basic fiber types, single-mode and multimode. Single-mode fiber has a core diameter of 8 to 10 microns and is normally used for long distance requirements and high-bandwidth applications. Multimode fiber has a core diameter of 50 or 62.5 microns and is usually used in buildings. The picture below shows single-mode and multimode fiber with different core diameters.

Cable Construction Selection

Another important consideration when specifying optical fiber cable is the cable construction. There are three main types of cable configurations: buffered fiber cable, simplex cable and multichannel cable.

Buffered Fiber Cable: There are two kinds of buffered fiber. The first is a loose buffer tube construction where the fiber is contained in a water-blocked polymer tube that has an inner diameter considerably larger than the fiber itself. The loose buffer tube construction offers lower cable attenuation from a given fiber, and a high level of isolation from external forces. Loose buffer cables are typically used in outdoor applications and can accommodate the changes in external conditions. The second is a tight buffer tube design. A thick buffer coating is placed directly on the fiber. The tight buffer construction permits smaller, lighter weight designs and generally yields a more flexible cable. A comparison of these two cable constructions is shown below.

Simplex Cable: A simplex fiber optic cable has only one tight buffered optical fiber inside the cable jackets. Simplex fiber optic cables are typically categorized as interconnect cables and are used to make interconnections in front of the patch panel. They are designed for production termination where consistency and uniformity are vital for fast and efficient operation.

Multichannel Cable: Building multiple fibers into one cable creates a multichannel cable. This type of cable is usually built with either a central or external strength member and fiber bundled around or within the strength member. An external jacket is used to keep the cable together.

40GBASE QSFP+ (quad small form factor pluggable) portfolio offers customers a wide variety of high-density and low-power 40 Gigabit Ethernet connectivity options for data center, high-performance computing networks, enterprise core and distribution layers, etc. And each kind of 40GBASE QSFP+ transceiver has its special applications. 40GBASE-LR4 QSFP+ transceiver is a common 40 Gigabit Ethernet connectivity option. Here is some basic information about 40GBASE-LR4 QSFP+ transceiver.

Introduction

40GBASE-LR4 QSFP+ module supports link lengths of up to 10 kilometers over a standard pair of G.652 single-mode fiber with duplex LC connectors. The 40 Gigabit Ethernet signal is carried over four wavelengths. Multiplexing and demultiplexing of the four wavelengths are managed within the device. The letter “L” stands for long, the “R” denotes the type of interface with 64B/66B encoding and the numeral 4 indicates numeral 4 indicates that the transmission is carried out over a ribbon fiber with four singlemode fibers in every direction. Each lane has a 10 Gbit/s data rate. 40GBASE-LR4 QSFP+ transceiver modules are compliant with the QSFP+ MSA and IEEE 802.3ba 40GBASE-LR4. The picture below shows a Mellanox MC2210511-LR4 compatible 40GBASE-LR4 QSFP+ transceiver.

Two Types of 40GBASE-LR4 QSFP+ Transceiver

There are mainly two of 40GBASE-LR4 QSFP+ transceivers, 40GBASE-LR4 CWDM (coarse wavelength division multiplexing) QSFP+ transceiver and 40GBASE-LR4 PSM (parallel single-mode fiber) QSFP+ transceiver. This part mainly talks about these two 40GBASE-LR4 QSFP+ transceiver types.

40GBASE-LR4 CWDM QSFP+ transceiver, such as QSFP-40GE-LR4, contains a duplex LC connector for the optical interface. It can support transmission distance of up to 10km. A 40GBASE-LR4 CWDM QSFP+ transceiver converts 4 inputs channels of 10G electrical data to 4 CWDM optical signals by a driven 4-wavelength distributed feedback (DFB) laser array, and multiplexes them into a single channel for 40G optical transmission. Then the receiver module accepts the 40G CWDM optical signals input, and demultiplexes it into 4 individual 10G channels with different wavelengths.

40GBASE-LR4 PSM QSFP+ transceiver is a parallel single-mode optical transceiver with an MTP/MPO fiber ribbon connector. It also offers 4 independent transmit and receive channels, each capable of 10G operation for an aggregate data rate of 40G. The transmitter module accepts electrical input signals compatible with common mode logic (CML) levels. All input data signals are differential and internally terminated. The receiver module converts parallel optical input signals via a photo detector array into parallel electrical output signals. The receiver module outputs electrical signals are also voltage compatible with CML levels.

Applications

QSFP-40GE-LR4 supports 40GBASE Ethernet rate only, whereas the QSFP-40G-LR4 supports OTU3 data rate in addition to 40GBASE Ethernet rate. 40GBASE-LR4 QSFP+ transceivers are most commonly deployed between data-center or IXP sites with single mode fiber.

Fiberstore offers customers a wide variety of 40GBASE-LR4 QSFP+ transceivers for your high-density and low-power 40 Gigabit Ethernet connectivity options, including 40GBASE-LR4 CWDM QSFP+ transceiver and 40GBASE-LR4 PSM QSFP+ transceiver, like Cisco QSFP-40GE-LR4 40GBASE-LR4 QSFP+ transceiver. Fiberstore also provides wide brand compatible 40G QSFP+ transceivers, such as Brocade QSFP+, Dell QSFP+, Juniper QSFP+, Mellanox QSFP+, and HP QSFP+. Each fiber optic transceiver provided by Fiberstore has been tested to ensure its compatibility and interoperability. Please rest assured to buy.