In the modern society, video multiplexer plays an important part in most public places and special events to monitor and record the real-time videos. Video, after years of development, has become one important way of communication after audio. Video multiplexer, as the typical application of videos, has also played an important party in improving the office efficiency technology, and in many ways have mature application.

At first, let see what’s exactly a video multiplexer, to be simple, a video multiplexer is an transmission device that convert 1 to more channels analog video signals to optical signals using various encodes and finally enable them transmit via the optical fiber medium. Since two technologies are usually used for this conversion, it can be divided into analog video multiplexer and digital video multiplexer. The principle is to modulate the signals to the light and transmit through fiber optics.

The video multiplexer encodes the multi channel video signals and convert them to optical signals to transmit on optical fibers, fiber-optic video multiplexer can simultaneously transmit 1-64 channels of 8bit digitally encoded video/return or bidirectional data/ un-directional or bidirectional audio/ Ethernet/ Telephone/ Dry contract over one multi-mode or single mode optical fiber. These multiplexers are typically used in applications where the cameras have PTZ capabilities.

The Classification of the Digital Video Multiplexer
Supported channels: there are 1, 2, 4, 8 channel video multiplexers and more channel video multiplexer with PTZ control data

Single types: there can be divided into digital video multiplexer and analog video multiplexer.

Interface types: there are 1-64 channels Video multiplexer, Video+Data Multiplexer, Video+Audio Multiplexer and Video+Audio+Data multiplexer, Phone Multiplexer, Ethernet Multiplexer, etc.

SDH Multiplexer (Synchronous Digital Hierarchy, Synchronous Digital series) capacity is biger, general 16 e1 to 4032 e1.

PDH Multiplexer (Plesiochronous Digital Hierarchy, quasi synchronous Digital series) is small capacity multiplexer and generally used in pairs, also called point to point application, capacity is commonly 4E1, 8E1, 16E1.

SPDH Multiplexer (Synchronous Plesiochronous Digital Hierarchy) is between PDH and SDH. It is a PDH transmission system that based on the PDH code speed adjustment principle at the same time, use as far as possible parts of the SDH network technology.

With the development of technology and the increasing demand on security, the Monitoring multiplexers are widely applied for most security applications such as remote business meeting, distance education, hospital, and many other security engineering applications. Current multiplexer technology is becoming more and more mature, the monitoring multiplexer can achieve in a core optical fiber transmission on multiple video, audio, data, telephone, Ethernet, E1 signal, alarm and so on many kinds of signals.

 The SFP+ specification was first published on May 9, 2006, and version 4.1 published on July 6, 2009. Just as its name suggests, SFP plus is an Enhanced pluggable module form SFP transceivers, targets at 10Gbps Ethernet and 8.5Gbps Fiber Channel systems, it becomes a popular industry format supported by many network component vendors. SFP+ transceiver is currently  the smallest size 10G transceiver compared with the former 10G transceivers X2 and XENPAK.

The SFP+ supports data rates up to 10 Gbit/s, 8 Gbit/s Fibre Channel, 10 Gigabit Ethernet and Optical Transport Network standard OTU2. SFP+ transceivers are used as linking the equipment to fiber optic networks. 10G SFP+ offers customer a wide variety of 10 Gigabit Ethernet connectivity options for data center, enterprise wiring closet, and service provider transport applications.

SFP + Features:

Standards : IEEE 802.3z 1000BASE-SX; 1000BASE-LX;

Hot-Pluggable SFP+ Footprint;

Duplex/ Simplex LC Optical Transceiver;

Digital Diagnostic Function;

Class 1 Laser International Safety;

Standard IEC-60825 Compliant;

Compatible with SFP+ Multi-Sourcing Agreement (MSA);

Dual Fiber Strands SFP+ Modules;

CWDM Dual Strands SFP+ Modules;

C Band DWDM Dual Fiber Strands SFP+ Modules;

Single Fiber Strand (Bi-Di) SFP+ Modules.

SFP+ has been replaced the XFP 10G modules and became the mainstream. It has many advatanges compared with SFP, XENPAK or XFP modules.

SFP+ Compared with SFP:

SFP has a maximum data rate of 5Gb/s whereas SFP+ is designed for 10Gb/s;

The SFP receptacles and plugs are not as well impedance matched as SFP+ receptacles and plugs;

SFP is based on IEEE802.3 and SFF-8472, but SFP+ is compliance with the protocol of IEEE802.3ae, SFF-8431, SFF-8432.

SFP+ Compared with former XENPAK or XFP modules:

SFP+ is much more lighter weight and lower consumption, is with more compact size and shape;

The size of SFP+ is smaller than XFP, thus it moves some functions to motherboard, including signal modulation function, MAC, CDR and EDC;

SFP plus is lower power consumption, this results in more densely installation capability than currently used 10G transceivers;

SFP+ modules leave more circuitry to be implemented on the host board instead of inside the module;

The cost of SFP+ is lower than XFP, X2 and XENPAK.

By now, as the high density data centers and enterprise networks, it is well acknowledged as the ultimate choice for the 10G SFP+ module. 10G SFP+ has become the optical module form factor of choice for 10 Gbps links due to its cost, size and power advantages over other module types.

Many fiber optic products supplier, such as Cisco, Finisar, and Sumitomo, have released the SFP+ transceivers. SFP+ tansceiver ensures the 10Gbps data transmission and the most densely installation capability as well as the lowest cost. Ingellen, an original manufacturer, supply SFP+ transceivers that are fully compatible with industrial standards, they feature good price and excellent performance.

 Optical transceiver is an Ethernet transmission media converter unit which transfer a short distance twisted pair electrical signals to optical signals over long distances swap, it is also called the photoelectric converter (Fiber Converter) in many places.

Single-mode fiber optic transceivers: 20-120 km transmission distance. Multimode fiber transceiver: transmission distance up to 2 km. According to the optical fiber, it can be divided into multi-mode fiber optic transceivers and single-mode fiber transceiver. Since the different optical fiber the fiber transceivers used, the transmission distance is different. Generally, the multimode transceiver transmission distance is within 2 km while the single-mode transceiver range from 20 km to 120 km. What should be noted is that due to the different transmission distance, so as the transmission power of the fiber optic transceiver itself, the receiver sensitivity and the working wavelength: Transmitting power of a 2 km fiber optic transceiver is generally between -20 ~-14db, receiver sensitivity -30db with 1310nm wavelength; 120 km fiber-optic transceiver transmitting power is between -5 ~ 0dB receiver sensitivity -38dB, using a wavelength of 1550nm.

According to the required number of optical fiber, they are single-fiber optical fiber transceivers that the received data are transmitted on a single fiber. The essence of an optical multiplexer is to achieve the electro-optical, photoelectric conversion with the images, voice or data signals. To be simple it is just a transmission between electrical signal and optical signal, the purpose is to make various signals transmitted in optical fibers. From the transmission principle, Optical multiplexer can be divided into two kinds: analog multiplexer and digital multiplexer. The formal mainly modulate and demodulate image, voice or data signals by frequency modulation, amplitude modulation and finally output. While the digital multiplexer is transmit by analog-to-digital, digital-to-analog conversion (i.e., 0,1 / 1,0 digital encoding process).

Optical fiber as the transmission medium of optical multiplexer and transceivers, it features small signal attenuation, long transmission distance, good confidentiality, strong anti-interference ability, etc. The optical multiplexer that available on the current market can not only transmit muli-channel video, data and voice signals on a single core fiber but also but also achieve the telephone, computer network, E1 (2M) port, network management, and many other functions transmitting on it, which have saving lots of fiber resource. What’s more the optical multiplexer has the same function with a network video server, which can transmit video and network data at a same time. Besides, the optical multiplexer is also regarded as an universal device that can used to form either a LAN or a public network.

 Ingellen, a worldwide leading manufacturer of fiber optic products, provides a wider choice for the majority of demand platform. It offers custom service for SFP transceivers with the required specifications provided like OC-3/STM-1/155M SFP, OC-12/STM-4/622M SFP, OC-48/STM-16/2.5G SFP, 1.25G SFP, 4G SFP, etc. In the below list, you will have a more particular knowledge of OC-3, OC-12 and OC-48 SFP transceivers.

Optical Carrier(OC) transmission rates are a standardized set of specifications of transmission bandwidth for digital signals, that can be carried on Synchronous Optical Networking (SONET) fiber optic networks. Transmission rates are defined by rate of the bitstream of the digital signal and are designated by hyphenation of the acronym OC and an integer value of the multiple of the basic unit of rate, e.g., OC-48. The base unit is 51.84 Mbit/s. Thus, the speed of optical-carrier-classified lines labeled as OC-n is n × 51.84 Mbit/s.

Optical Carrier classifications are based on the abbreviation OC followed by a number specifying a multiple of 51.84 Mbit/s: n × 51.84 Mbit/s => OC-n. For example, an OC-3 transmission medium has 3 times the transmission capacity of OC-1. According to the the abbreviation OC, OC transmissions can be divided into OC-1, OC-3, OC-3c / STM-1, OC-12 / STM-4, OC-24, OC-48 / STM-16 / 2.5G SONET, OC-192 / STM-64 / 10G SONET and OC-768 / STM-256. Along them, OC-3, OC-12 / STM-4 and OC-48 / STM-16 / 2.5G SONET are the most commonly used in networking.

OC-3 SFP
OC-3 SFP module is a network line with transmission speeds of up to 155.52 Mbit/s(payload: 148.608 Mbit/s; overhead: 6.912 Mbit/s, including path overhead). Depending on the system, OC-3 is also known as STS-3, STM-1 (SDH). OC-3 SFP modules are often used for Fast Ethernet, SDH/SONET and FTTx applications.

OC3 SFP module is specifically designed for the high performance integrated duplex data link over single mode optical fiber. These transceiver modules are compliant with the SFP Multisource Agreement (MSA). With the hot pluggability, these modules offer an easy way to be installed into SFP MSA compliant ports at any time without the interruption of the host equipments operating online.

OC-12 SFP
OC-12 SFP is a network line with transmission speeds of up to 622.08 Mbit/s (payload: 601.344 Mbit/s; overhead: 20.736 Mbit/s). OC-12 lines are commonly used by ISPs as Wide area network (WAN) connections. While a large ISP would not use an OC-12 as a backbone (main link), it would for smaller, regional or local connections. This connection speed is also often used by mid-sized (below Tier 2) internet customers, such as web hosting companies or smaller ISPs buying service from larger ones.

OC-48 SFP
OC-48 is a network line with transmission speeds of up to 2488.32 Mbit/s (payload: 2405.376 Mbit/s (2.405376 Gbit/s); overhead: 82.944 Mbit/s). With relatively inexpensive interface prices, and being faster than OC-3, OC-12 SFP connections, and even surpassing gigabit Ethernet, OC-48 connections are used as the backbones of many regional ISPs. The OC-48/STM-16 capabilities on the Cisco ONS 15600 Series consist of two optical line cards, providing interface specifications that meet the varied application needs of the service provider.

Interconnections between large ISPs for purposes of peering or transit are quite common. As of 2005, the only connections in widespread use that surpass OC-48 speeds are OC-192 and 10 Gigabit Ethernet.

OC-48 is also used as transmission speed for tributaries from OC-192 nodes in order to optimize card slot utilization where lower speed deployments are used. Dropping at OC-12, OC-3 or STS-1 speeds are more commonly found on OC-48 terminals, where use of these cards on an OC-192 would not allow for full use of the available bandwidth.

Ingellen also offers various type of fiber optic devices, including all kinds of fiber optic transceivers, video multiplexers, media conventers and passive components and so on, which are all high performance but low price. Enjoy your shopping at www.ingellen.com. You can contact [email protected] for more detailed product or service information. Ingellen guarantees you will beyond your expectation there.

 Optical isolator is a necessary passive component that widely used in fiber optic communication networks. It is used to prevent unwanted light feedback into the sensitive devices or components. As we know, light can be reflected back and forth, which will also happen in the fiber optic networks.

But the fact is most of the refection will affect the stability of the system especially for lasers. Laser is essentially a resonant cavity between two semi-transparent mirrors. The lasing process happens between these two mirrors. The lasing process is very delicate and can be easily interfered. If back-reflected and scattered light enters into the laser, the lasing process will fluctuate and the output power of the laser will fluctuate. However to prevent the bad result caused by this unwanted refection, a fiber optic isolator is needed here. A fiber optic isolator is also called optical diode, which is issued to prevent any light from reflecting back down the fiber, stopping backscattering and feedback problems on these sensitive components in the networks.

Most of optical isolators in the current market are Faraday isolator that is based on Faraday rotators. According to the polarization sensitivity of the optical isolator, it can be divided into polarization sensitive and insensitive Faraday isolators:

Polarization-sensitive Faraday Isolators

Polarization-sensitive faraday isolator is the simplest type which only works when the input beam has a prescribed direction of linear polarization. This type of faraday isolator is composed of a pair of linear polarizers and a Faraday rotator.

The two linear polarizers are oriented so the planes in which they polarize light are 45° apart. The Faraday rotator sits between these two polarizers. The Faraday rotator rotates the plane of the polarization of light by 45° in a single direction no matter the light traveling direction, may it be from the first polarizer(left) or the second polarizer(right). So if the light goes from the first polarizer to the second polarizer (from left to right). The Faraday rotator will rotate the polarized light from the first polarizer by 45° which exactly matches the polarization plane of the second polarizer. So the light will go through with minimum loss.

But if the light goes from the second polarizer to the first polarizer (from right to left). The Faraday rotator will rotate the polarized light from the second polarizer also by 45°. But since it rotates the light as the same direction as from left to right, this time when the rotated light gets to the first polarizer, the polarization planes of the polarized light and the first polarizer are 90° cross. So all light are blocked and no light will go through.

Polarization-insensitive Faraday Isolators

In order to overcome this limitation of polarization sensitively, optical isolators have been developed which are polarization insensitive type. That is, regardless of the polarization state of the input beam, the beam will propagate through the isolator to the output fiber and the reflected beam will be isolated from the optical source.

Such devices are often required in the context of fiber optics, because many fibers are not polarization-maintaining. In particular, optical fiber communication systems are usually operated with undefined polarization state, and Faraday isolators as well as other components are then required to work with arbitrary polarization states.

The basic principle of a polarization-insensitive isolator is to first spatially separate the orthogonal polarization components of the input beam with some kind of polarizer, then send both through a Faraday rotator, and combine them again in the second polarizer. Since there is an arbitrary relative phase change between the two polarization components, polarization-insensitive isolator will in general not preserve the polarization state.

Insert loss and degree of isolation are essential features for the optic isolator. The insertion loss is mainly depend on the type and quality of the polarizers used. A high degree of isolation is generally more difficult to achieve for high-power devices, where the beam in the Faraday medium covers are larger area and is thus more sensitive to field inhomogeneities. The fiber optic isolators can be pre-installed with various kinds of fiber connectors. Ingellen offers various type of fiber optic isolator devices which features high isolation and high return loss, minimal polarization dependent loss, and very low polarization mode dispersion.