Category Archives: Optical Solutions

Micrel Launches New Limiting Post Amplifier for 10Gbps FTTH PON Network

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Micrel Semiconductor has introduced SY88053CL and SY88063CL limiting post amplifier. Both devices support the expansion of the next generation passive optical network (PON) FTTH XGPON and 10GEPON optical line terminal (OLT) ideal for applications. The product line also applies to support multi-rate applications. Fiber optic transceiver module, the maximum rate is up to 12.5Gbps. Support for Ethernet, Fibre Channel, OTN and OBSAI data rate.
“These new devices offer an impressive number of features including a new level of high bandwidth, high input sensitivity with programmable, wide range SD Assert and LOS De-Assert threshold levels, 4dB of electrical hysteresis, and stable SD Assert and LOS De-Assert timing to meet the stringent requirements of next generation PON network,” stated Tom Kapucija,director of marketing for the high speed communications business, Micrel. “Thesse features enable link efficiency optimization with increased system reach, higher link up-time and higher payload bandwidth.”Vice president for the timing and communications business group, Rami Kanama, said, “As the demand for more data at higher speeds increases, carries need to meet this demand by upgrading their line-side equipment and revamping their networks. Micrel continues its effort in addressing this demand at the device level. Our new optical limiting amplifier delivers speed, performance, and features that is critical to solving technical difficulties facing next generation FTTH, Enterprise, and transport networks. With increased link efficiency, system operators can achieve higher data transmission performance and potentially reduce carries’ CapEx and OpEx.”
Both devices incorporate fast SD Assert and LOS De-Assert times across the entire differential input voltage range of 5mVPP to 1800mVPP which enables improved link efficiency and optimization. In 3mVPP to 30mVPP wide LOS / SD threshold range provides a 4dB electrical hysteresis.  Integrated 50 Ohm input and output impedances optimize high speed signal integrity while reducing external component counts and in turn, cost. TTL compatible JAM input enables a SQUELCH function by routing back the LOS or SD signal.
The SY88053CL enable user adjustable decision threshold adjustment for optimized Bit Erro Rate operation in noisy applications with asymmetrical noise distribution while the SY880563CL provides a user selectable Digital Offset Correction function that automatically compensates for internal device offsets in the high speed data path. Other features include multi-rate 1Gbps to 12.5Gpbs operations, optional LOS or SD output, selectable RXOUT +/ RXOUT- signal polarity (SY88053CL) and 25ps typical rise / fall time. Beyond the current customer demand through increased performance margins, improved manufacturability of the module, while reducing costs. By increasing each node and the downstream branch exceeds 512ns link budget margin established, to improve the efficiency and data throughput of the link. By optimizing in a noisy environment and the error rate or RAMAN EDFA Optical Amplifier noise characteristics of asymmetric compensation, expanding the system extends the scope to improve the data throughput.
Both devices offer a wide power supply range of 3.3V+/-10 percent and come in an industrial temperature range of -40 degC to +85-degC and a tiny 3mm x 3mm QFN package.
Source: www.fs.com/news/

WDM Networks: The Transponder

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In optical fiber communications, WDM Transponder sends and receives the optical signal from a fiber. A transponder is typically characterized by its data rate and the maximum distance signal travels.

The transponders are of two types namely transmit transponders and receive transponders. The function of transmit transponder is to convert the incoming optical signal into pre-defined optical wavelength. The transponder (transmit) first converts the optical signal to an electrical signal and performs reshaping, retiming and retransmitting functions, also called 3R functions. The electrical signal is then used to drive the laser, which generates the optical signals having optical wavelength. The output from the all transponders (transmits) is fed to combiner in order to
combine all optical channels in optical domain. In receive transponder, reverse process takes place.

Individual wavelengths are first split from the combined optical signal with the help of Optical Splitter and then fed to individual receive transponders, which convert the optical signal to electrical, thus 3R function and finally convert the signal back to the optical. Thus the individual channels are obtained. As the output of the transponder is factory set to a particular wavelength, each optical channel requires unique transponder.

Often, fiber optic transponders are used for testing interoperability and compatibility. Typical tests and measurements include jitter performance, receiver sensitivity as a function of bit error rate (BER), and transmission performance based on path penalty. Some fiber optic transponders are also used to perform transmitter eye measurements.

The transponder according to the invention utilises delays that are switchable between different optical fiber lines, so as to be able to select many different lengths without the necessity of re-designing the same transponder. Moreover, the transponder according to the invention uses a Single Side Band (SSB) optical component which produces an optical shift of the frequency of the radar signal, that avoids the drawbacks and solves the problems of the traditional electrical systems. The transponder according to the invention is comprised in multifunctional radar systems and allows at least three different uses: the first is the systems calibration on the basis of moving targets that are simulated in the production step,the second one is the performances test of a radar that has already been calibrated in the step of the system acceptance by the client (Field Acceptance Test), and the third one is the support to the identification of possible faults and nonworking partsof the radar, during the operation life of the same radar system. The transponder of the invention comes out to be easily producible and transportable.

An integrated transponder will also be needed: one transponder that couples to 10 individual fibers at a much lower cost than 10 individual transponders. With a super-channel transponder, several wavelengths are used, each with its own laser, modulator and detector. Photonic integration is the challenge to achieve a cost-effective transponder.

The Difference Between Fiber Optic Transponder And Fiber Optic Transceiver

A transponder and transceiver are both functionally similar devices that convert a full-duplex electrical signal in a full-duplex optical signal. The difference between the two is that fiber transceivers interface electrically with the host system using a serial interface, whereas transponders use a parallel interface. So transponders are easier to handle lower-rate parallel signals, but are bulkier and consume more power than transceivers.

The Application of 10G PON Technology

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With the major carriers “Broadband speed”, “Light of Copper” project extensively, The future will be a multimedia broadband services, video on demand, interactive games as the main feature, high-bandwidth, integrated operators will be judged promoted by the merits of the standard broadband products.
Under the broadband Fiber Optic Network in the trend, PON technology has become the world’s attention to various telecom operators hot technology is one of the operators to implement “broadband speed”, “Light of Copper” engineering technology base. Wheter EPON, or GPON, which provides only for the uplink and downlink bandwidth of 1G or 2G, but with the current interactive network TV (IPTV), high definition television (HDTV), online games, video services and other large flow, a large broadband business development and popularization of the per-user bandwidth demand is expected to grow every three years, a trend of increasing magnitude, from the future operator of long-term trends, per-user bandwidth demand will be 50-100 Mbit/s between. This way, EPON and GPON are unable to meet the future needs of the development of broadband services, the existing PON port bandwidth, there will be a bottleneck. Therefore, ITU-T, FSAN, IEEE and other major standards organizations begin the next generation of PON technology research.
Similar to 1G PON Technology, 10G PON and 10G EPON technology is still divided into two camps 10G GPON. In IEEE 802.3av 10G EPON standards, maximizing follows the usual IEEE 802.3ah content, with good upward compatibility.
>> 10G PON technical analysis
Recalling the history of PON technology can be found in each of the PON technology from birth to the end of the day have to go through large-scale commercial development of technical standards, the relevant chip and optical module development, test and production, the creation of experimental and commercial bureau 4 stages of deployment, which lasted five years or so, each one of which will go through several stages of development of the argument.
* Standardization Advances
Standards are mature is the precondition of judging whether a technology have lead to condition. At this stage, including IEEE, ITU-T, FSAN and number of ongoing international standardization organizations 10G EPON and 10G GPON standards development work of two technologies. Overall, the 10G EPON technology start time earlier than 10G GPON, therefore, the current standardization process of 10G EPON slightly faster than 10G GPON.
a. 10G EPON
Technologies with 1G EPON, 10G EPON standards are mainly led by the IEEE to complete. IEEE organization at September 12, 2009 released the 10G EPON international standards 802.3av, this standard focuses on the physical layer 10G EPON technology research, followed the tradition of 1G EPON MPCP protocol, the 1G EPON downlink bandwidth increases to 10G at the same time, to ensure that the operator of the original investment is not compromised and 10G EPON smooth upgrade, IEEE 802.3av standard defines and 1G EPON ONU coexist in the same ODN network of 10G EPON ONU standard parameters.
Further, in IEEE 802.3av standard, the physical layer defines two parameters: one asymmetric model, which 10G rate downlink and 1G rate uplink; other is symmetrical pattern, i.e. uplink rate and downlink rate are both 10G. Asymmetric mode can be considered as a transitional form symmetrical patterns, in the early less demand for upstream bandwidth and cost sensitive applications, you can use an asymmetric form. With the development of business and technology progress, will be gradually transition to a symmetrical mode.
b. 10G GPON
According to ITU-T Study plans, NGPON will experience two standard phases: the first phase is the coexistence with GPON, GPON ODN heavy use of XG-PON, which in turn contains the uplink and downlink phase XG-PON1 asymmetric and symmetric XG-PON2 two kind of model; Second stage is completely new ODN’s NGA2. High concern Wavelength Division Multiplexing – Passive Optical Network (WDM-PON) technology areas belong to the second stage, it was adopted in a fiber access network using multiple wavelengths to achieve the expansion, but the burst mode CWDM, colorless ONU transceivers, tunable WDM devices and some difficult technology can not break, WDM-PON is still at the proof stage.
In the end of September 2009 meeting of the ITU-T SG 15 plenary session, Q2 Working Group officially launched the NG-PON standard text in the first stage, that overall demand for next-generation PON systems (G.987.1) and Physical Layer Specifications (G.987.2), and also developed in mid-2010, publishing transmission convergence layer (G.987.3) and management control interface (G.988) standards program.
* Technical Parameters
Wheter IEEE 802.3av, or ITU-T G.987 protocol suite, all relevant technical parameters for 10G PON physical layer index, optical power budget to make a detailed definition. However, due to the two major standards organizations considered the starting point, the technical indicators are also some differences.
a. 10G EPON
There are four key points of 10G EPON technology:
1. Defines six 10G EPON optical power budget, in view of the asymmetric mode PRX10, PRX20 and PRX30 as well as for symmetric mode PR10, PR20 and PR30, these six kinds of optical power budget model is basically to meet the construction needs of the service provider network;
2. 10G EPON technology in achieving the 1G EPON conventional multi-point control protocol layer (MPCP) based on the forward compatibility, also extended the original message type, for reporting optical terminal equipment (OLT), ONU Optical Transceiver switch time to meet the 10G EPON system requirements;
3. 10G EPON uses (255, 223) Forward Error Correction (FEC) encoding method, the encoded with FEC coding for the same strain of 1G EPON, but its strong support 10G EPON coding gain can lower the sensitivity of the optical receiver;
4. 10G EPON uplink and downlink wavelength for the re-planning, downlink using 1268-1280nm wavelength, then reuse the original uplink of 1G EPON 1575-1580 nm wavelength, the wavelength in order to avoid conflicts, 10G EPON uplink only use time division multiple access (TDMA) manner.
b. 10G GPON
Has been released G.987.1 standard that defines 10G GPON system’s overall technical requirements and system architecture, clearly put forward the 10G GPON system to ensure good QoS, based on the traditional telecom services to fully support all emerging businesses and the same time, also provides dynamic Bandwidth Allocation (DBA) algorithm, energy saving, authentication and encryption related content to inherit the original 1G GPON technology; The G.987.2 is the focus of standardized 10G GPON physical layer parameters, including downlink rate, ODN power budget, splitting ratio, up and down the line wavelength range and line coding, etc., although down the line of 10G EPON same wavelength range and 10G EPON, GPON but due to the wavelength with 1G is not conflict, therefore, 10G GPON uplink and downlink are used wavelength division multiple access (WDMA) manner.
* Industrial chain development
A complete industrial chain, including chip PON, optical modules and equipment three links. If to analysis PON industry chain, it need to start from the three links, analysis of every link current development status and future development trend.
Overall, 10G EPON and 10G GPON is currently not reach the requirements of large-scale commercial applications, although some equipment manufacturers have recently introduced a 10G EPON or 10G GPON products, and with operators, the creation of some experimental inning, but still in the laboratory testing phase, is still some distance away from the large-scale commercial.
>> Conclusion

10G PON technology to meet future access networks, “large-capacity, fewer offices,” the direction of development, while improving access speed, supports larger branching ratio, covering more users. Therefore, 10G PON technology will become the future telecom operators to achieve “broadband speed”, “Light of Copper” and other broadband network construction hot technology for sustainable development.

Protocol Converter Is The Key Component In Communication

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The Protocol Converter, a device converts one protocol into other protocol, is ideal for situations where data from monitored equipment is incompatible with the protocols used by the building management system (BMS) or network management system (NMS), such as in cases where legacy monitoring systems are present. The ability of the protocol converter to accept up to 1,024 inputs over 32 modules means flexible integration with multiple alarm and management systems using one simple device. Protocol converters are widely used in process or industrial automation, building automation, substation automation, automatic meter reading and vehicle automation applications.

Protocol converters are normally used with switches, PCIe network cards and fiber media converters, CWDM and DWDM equipment, PDH multiplexers etc. Protocol converter series may put into action the actual transformation in between single E1 protocol port as well as protocol ports of V.35, V.24, RS232 or Ethernet within the tranny system; it may be thoroughly utilized in numerous being able to access problems with regard to providers as well as commercial clients, for example DDN, ATM, as well as for that transformation in between router and E1 port, or even the actual occasion exactly where Ethernet tend to be interconnected from divided internet websites through SDH or even additional tranny gear.

1. Protocol converter can offer local, remote loop-back functions, commanded remote device loop-back as well as pseudo-random code testing perform; loop-back perform may be used without influence on normal network data conversation and can not really lead to the actual meltdown of network;

2. E1 port may support 120ohm/75 ohm opposition concurrently;

3. V.24 port may assistance a rate of 64K or 128K (optional), and may carry out tranny from any kind of specific time-slot within E1 port; also it can function under DTE and DCE modes;

4. V.35 user port may support N*64K (N=1~32) adaptive rate, and may assistance inner, exterior and slave clock modes, in order to end up being designed in order to numerous programs; also it can function under DTE and DCE modes;

5. RS232 port may assistance the actual a good adaptive rate lower than 115.2K;

6. Ethernet port may assistance N*64K (N=1~32) adjustable rate, and may assistance four channels of Switched Ethernet ports and may end up being channel-isolated; Ethernet mode may assistance 10M/100M semi-duplex as well as 10/100M full-duplex modes as well as adaptive mode (optional), as well as assistance VLAN protocol;

7. Ethernet protocol convertor may identify the actual delivering as well as getting information caution associated with E1 port instantly, as well as switch off Ethernet function instantly.

How To Choose A Converter

There are basically two types of protocol converter which are listed below.

1. Software Protocol Converters
2. Hardware Protocol Converters

Some of the most popular industrial automation protocols are DF-1, CAN (Controller Area Network), Ethernet RS232 Converter, Ethernet RS422 Converter, ControlNet, DeviceNet, HostLink Protocol, Profibus, Modbus, Honeywell SDS, HART Protocol, EtherNet/IP etc. And some Industrial control system protocols like MTConnect, OPC, OPC UA. Select the converter that best matches your application and communication setup, keeping in mind three key features:

Number of connections—some converters support single connections, while others provide as many as 32 multiple connections with multiple serial ports.

Baud rate—we have seen converters with baud rates as high as 921kbaud. Converters with lower baud rates are less expensive, but their performance is slower.

Connectivity protocol—the converter must support the protocol used by your network, either TTL serial, RS-232, RS-422, or RS-485.

Consider the number of connections, baud rate and connectivity protocol, you can finally buy a protocol converter meet your applications.

To Introduce Optical Communication and Internet Technology

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Technology of terabit optic circuit packet integrated switching system
New exchange system and integrated optic circuit packet layers will be provided to meet the large capacity, high quality, low cost and effective demand so as to adapt to the cable wireless traffic spikes in the service in the future.
A connection-oriented packet transport technology is considered to be an effective way to improve the performance of packet data transmission. It is necessary, can put a layer of transport network in the direction of capital spending and minimizing operating costs to overcome the network provider’s storage and traffic increase of income. And unified control mechanism is applied to the network resource allocation, flexible wavelength circuit and packet layer according to the service characteristics. The key technologies of the system are as followings.
• Technology of Terabit Optic-Circuit-Packet Integrated Switching System
  * Connection-oriented Packet Transport
  * Optic-Circuit-Packet Integrated Switch
  * Optic-Circuit-Packet Layer Integrated Control/Management
• Technology of beyond-100G Optical Transmission
  * Long-reach OTN Transceiver

  * Short-reach Ethernet Transceiver

Technology of terabit optic circuit packet integrated switching system
Smart IDC Network Control Technology for Cloud Service
Along with the rapid spreads and changes of cloud services and the technologic growth of the components in the IDC, the IDC networks are demanding following changes.
Cloud optimized: The virtualization rate of the server is rising up to 10:1-100:1 and storage virtualization is also possible recently. So IDC is requiring the cloud-optimized virtualization to the network side which are connecting the virtualized cloud resources.
Flattened: There are network control needs to reduce the delay latency of virtualized server-to-server communications which is occuping up to 70%, to rise the utilization rate the link resources of L2 IDC networks of Tree-shape multi-layer hierarchical architecture with STP.
Auto-Managed: There are demands of integrated management of network and cloud resources between IDC and create/delete/VM migration to ensure seamless services in the cloud.

Therefore, our research target to develop the Smart IDC optical network solution to solve the current problems of IDC network with the 3 IDC network control technologies of the Cloud-Optimized Virtual Network Control technology, the Flattened IDC Network Control Technology and Auto-managed IDC network control technology.

High speed optical transmission technology

The rapid progress in optical transmission technology has been supporting the ever increasing transmission traffic. In particular, the WDM technology, it is by the end of last century, played a main role. However, the new technology needs to use data traffic exponentially. A solution is 100Gb/s transmission. IEEE announced 40G/100G Ethernet standard and ITU-T has completed ONT standard to accommodate 100G signals in DWDM backbone network. Recently, the 100Gb/s transmission technology has become the commercial deployment, in addition to the existing 10Gb/s and 40Gb/s. Already technologies beyond 100G or 400G are started being discussed. With a long-term perspective, it is a disruptive

technology, SDM (space division multiplexing) technology is seriously explored to harness the traffic in economic and energy efficient way.

Next Generation WDM-PON Technology
The WDM-PON is promising technology to provide broadband access offering optic-wireless converged next generation multi-application service with the highest quality.
There are many advantages of the WDM-PON:
* Using multiple wavelength on a single fiber, each of which carries a transmission bandwidth up to 10Gb/s at maximum; Therefore, the WDM-PON can reduce the optical access infrastructure;
* Suitable for long-reach application and possible to achieve OPEX reduction;
* Provide co-existence with legacy TDM-PON (EPON system, and GPON) systems and pay as you grow upgradability;
* Unique advantages of so-called protocol transparency, which means that it requires no specific transmission protocol, and the physical layer security, in addition to scalability in the increase of the bandwidth and guarantee of the quality of service based on bandwidth abundance.

Video Multiplexer For CCTV And Surveillance Applications

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Fiber-optic-based video and audio multiplexers are designed specifically for pro A/V and broadcast applications. Digital Video Multiplexer is usually applied in video area, especially for Security defensive system.

A video multiplexer, also called mux, includes digital video transmitter and receiver, is a device that put recordings of signals from multiple security cameras on one cassette. It handles several different video signals simultaneously. Video multiplexers can split a monitor into various display areas and vice versa, combine output signals from several cameras to a single monitor. It can be used as a stand-alone video processor to control various types of video views directly to a monitor and/or in conjunction with a VCR surveillance recorder. They can also provide simultaneous display and playback features. Some video multiplexers allow for remote access. They combine the best features of switchers and quads.

Typical Applications of Video Multiplexers:

1. Putting the camera signal on a video channel that is accessible to your television.
2. Configurable camera recording.
3. Closed circuit television (CCTV) and video surveillance applications because a video multiplexer can split a monitor into various display areas.
4. Automatic camera detection.
5. Various media and broadcasting applications.

How to Choose Video Multiplexer?

Video multiplexers come in a variety of configurations and features that conform to certain quality standards. The features may differ in quality of resolution, channels, refresh times, weight, power consumption, etc.

When choosing the video multiplexer, you should consider the number of camera inputs you need while taking into account future changes (in case of expansion). Features you need to look for include the following:

1. A time and date stamp that lets you know when any recorded activity took place.
2. An alarm output.
3. Motion detection.
4. Capability to be used with your computer software.
5. Use with either color or black-and-white cameras.

Multiplexers are described as simplex or duplex. This description indicates the number of multiplexing functions they can perform at any one time. Simplex multiplexers can perform only one multiplexing function at a time and will show a full-screen image, whereas duplex multiplexers show split options while continuing to record because it has two multiplexing processors in the same unit. Thus, a duplex multiplexer can display multiple cameras at the same time while multiplex-recording those cameras. Triplex multiplexers add a third multiplexing processor that has the ability to view live and recorded video on the same screen at the same time. Quadriplexers, or quads, use four camera connections per monitor. Quads can split the screen and display all the four cameras simultaneously. This means that the images are compressed and the image resolution may be low. In comparison, a multiplexer records each camera individually; thus, no loss from compression will occur. This is because when the output of a multiplexer is connected to a recording device, all cameras are individually recorded in sequence.

FiberStore supplies complete video surveillance systems, including Video Multiplexers, Video Data Multiplexer, Audio Video Multiplexers and video Audio Data Multiplexer. We supply video multiplexer in different channels, such as 1, 2, 4, 8, 16, 24, 32 channels. The Data Audio Video Multiplexer is ideal for a wide range of multiplexing and remultiplexing applications including Broadcast/Studio, CCTV audio and Professional AV applications.

NeoPhotonics Opens Factory in Dongguan of China

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FiberStore News

Summary: NewPhotonics last week announced the first shipments of optical transceiver modules out of its new, high capacity factory in Dongguan, Guangdong Province, China

NewPhotonics Corporation, a leading designer and manufacturer of photonic integrated circuit, or PIC, based optoelectronic modules and subsystems for bandwidth intensive high speed communications networks, last week announced the first shipments of optical transceiver modules out of its new, high capacity factory in Dongguan, Guangdong Province, China.

The new factory consists of approximately 80, 000 square feet of production spare, which includes approximately 50, 000 square feet of clean room area. The new production lines use state of the art manufacturing equipment for optical sub-assembly (OSA) fabrication and final module assembly and test. Module work cells are designed to support rapid reconfiguration of production lines, which allows quick reaction to the changing needs in the dynamic market of optical modules for high speed communications worldwide.

Dongguan factory is the latest addition to the company’s manufacturing capabilities. Another basement of manufacturing, assembly and test operations facilities is located in Shenzhen, China. Together with FiberStore, another fiber transceiver provider, forming the most competitive transceiver modules providers in China Silicon Valley, Shenzhen.

About NeoPhotonics
NeoPhotonics is a leading designer and manufacturer of photonic integrated circuit, or PIC, based optoelectronic modules and subsystems for bandwidth-intensive, high-speed communications networks.

About FiberStore
FiberStore is one of the main fiber optic network solutions providers, which offers complete range of electrical, optical and mechanical parts, such as fiber transceiver, direct attach passive &
active copper cables. The company’s products enable cost-effective, high-speed data transmission and efficient allocation of bandwidth over communications networks.

FiberStore Announces Availability of a New Product -Return Loss Tester JW3307B

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Summary: FiberStore announced the launch of a new return loss tester series JW3307B with enhanced features of high accuracy, compact appearance, stable and reliable test index, etc.

FiberStore is pleased to announce a new return loss tester – Muti-mode Loss & Insertion Loss Test Station JW3307B, which is a high performance loss test station that is designed specially for Optical Passive Components production Test and Lab Test.

The multimode interpolation return loss measuring instrument is specially used in the optical fiber cable and other fiber optic passive devices, optical active device and optical fiber communication system of insertion loss and return loss test.

At the moment, this new return loss tester combines three different working modes as a return loss meter, optical power and loss meter and a stable laser source in one test station.

JW3307B is a special circuit designed, with large dynamic range and weak signal accurate monitoring analysis, it can provide USB communication function, automatic storage of data.

“This highly accurate return loss tester used Two LCD displays, and efficiently reduced eye strain of users. Besides the leakage design of optical power meter module and light source module also greatly reduced the operation procedures” commented Li Longqing, product manager, fusion splicer systems for FiberStore.

Standard configurations of this JW3307B tester includes the main body, power supply cable, the interface adapter ( FC/SC/ST/φ 2.5/φ 1.25), User Manual, FC/APC-FC/APC reference patch cord, Scrambler, Extinction Module, Cleaning Cotton Stick, Fuse, USB Cable, PC software, Foot Pedal. If you want to know more about this MM Return Loss & Insertion Loss Test Station JW3307B, visit www.fs.com or contact us by sales@fs.com

Application of Optical Add-Drop Multiplexer

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What’s the Optical Add-drop Multiplexer?

An optical add-drop multiplexer (OADM) is a device used in wavelength-division multiplexing systems for multiplexing and routing different channels of light into or out of a single mode fiber (SMF). This is a type of optical node, which is generally used for the construction of optical telecommunications networks. An OADM may be considered to be a specific type of optical cross-connect.

A traditional OADM consists of three stages: an optical demultiplexer, and optical fiber multiplexer, and between them a method of reconfiguring the paths between the optical demultiplexer, the optical multiplexer and a set of ports for adding and dropping signals. The optical demultiplexer separates wavelengths in an input fiber onto ports. The reconfiguration can be achieved by a fiber patch panel or by optical switches which direct the wavelengths to the optical multiplexer or to drop ports. The optical multiplexer multiplexes the wavelength channels that are to continue on from demultiplexer ports with those from the add ports, onto a single output fiber.

Principles of OADM technology

General OADM node can use four port model (Figure 1) to represent, includes three basic functions: Drop required wavelength signal, Add rumored signal to other wavelengths pass through unaffected. OADM specific network process is as follows: WDM signal coming from the line contains mangy wavelength signals into OADM’s “MainInput” side, according to business required, from many wavelength signals to selectively retrieved from the end (Drop) output desired wavelength signal, relative to the end from the Add the wavelength of the input signal to be transmitted. While the other has nothing to do with the local wavelength channels directly through the OADM, and rumored signals multiplexed together, the line output from the OADM (Main Output) Output.


Figure 1 OADM basic model

OADM node technical classification

Optical drop multiplexer network technologies can be divided into two types, fixed optical drop multiplexer (Fixed OADM, FOADM) and reconfigurable optical drop multiplexer (Reconfigurable OADM, ROADM).

Fixed Optical Drop Multiplexer (FOADM)

FOADM to filter as the main component, and its function is fixed to join or retrieve certain light wavelengths. General common FOADM can be divided into three types, namely Thin Film Filter type (TFF type), Fiber Bragg Grating (FBG type) and integrated planar Arrayed Waveguide Gratings (AWG type).

Thin Film Filter (TFF FOADM)

* TFF FOADM using thin film between the filtering effect of the different refractive index.

Fiber Bragg Grating (FBG FOADM)

* FBG FOADM use of fiber Bragg grating filtering effect, with two circulator can become FOADM.

Arrayed Waveguide Gratings (AWG FOADM)

* AWG FOADM gererally used in semiconductor fabrication processes, the integration of different refractive index material is formed on a flat substrate in a planar waveguide, when different wavelength light source is incident through the couping after the import side, due to take a different path length, while the different phase delay caused by different wavelengths and thus produce certain wavelengths in the export side to form a constructive or destructive interference, making waves in the export side, the different wavelengths will follow the design on a different channel to reach, and thus achieve FOADM function.

Reconfigurable Optical Add/Drop Multiplexer (ROADM)

ROADM can always be adjusted with the distribution network to add and drop wavelength, which reconstruct the network resource allocation, the flexibility to meet the requires of modern urban network, so a flexible ROADM features, plus optical switch substantial advantage, making the current fastest growing ROADM based voa attenuator based ROADM (switch based OADM). ROADM mainly be the optical switch, multiplexer and demultiplexer composed, Switch-based OADM, mainly divided into Wavelength independent switch array and wavelength selection switch.


Type 1 Wavelength independent switch array

Type 2 Wavelength selective switch

All kinds of optical drop multiplexer performance comparison

OADM network applications

WDM ROADM optical fiber suitable for different network environments

OADM in the metropolitan network development tendency

1. Arbitrary choice must be retrieved, adding wavelength, the wavelength can take advantage of the limited resources, the node can be retrieved with the need to do to join the adjustment of the signal wavelength, and has a remote control functions. This can provide dynamic reconfiguration of optical communications network capable ROADM will be connected to the backbone network critical devices. And FOADM is used for wavelength demand network access will be smaller parts to reduce costs. Furthermore, ROADM use to all kinds of Tunable Laser, unable Filter, or wavelength selective optical switches and other components.

2. Must be able to convert incompatible wavelength suitable for the backbone network will be transmitted wavelengths. Therefore, OADM be combined with wavelength conversioin Transponder or other functional components.

3. Must be able to compensate for the node to make acquisistion, adding such action energy loss. Therefore, OADM optical amplifiers must be combined with functional components.

4. Wavelength signals related specifications, such as: the signal to noise ratio (S/N), the energy balance between the signal wavelength, etc., are required to meet network requirements. Therefore must be combined OADM Variable Optical Attenuator (VOA), dispersion compensation module (DCM) and other components.

How Much Do You Know About OADM

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The OADM, or optical add drop multiplexers, is a gateway into and out of a single mode fiber. In practice, most signals pass through the device, but some would be “dropped” by splitting them from the line. Signals originating at that point can be “added” into the line and directed to another destination. An OADM may be considered to be a specific type of optical cross-connect, widely used in wavelength division multiplexing systems for multiplexing and routing fiber optic signals. They selectively add and drop individual or sets of wavelength channels from a dense wavelength division multiplexing (DWDM) multi-channel stream. OADMs are used to cost effectively access part of the bandwidth in the optical domain being passed through the in-line amplifiers with the minimum amount of electronics.

OADMs have passive and active modes depending on the wavelength. In passive OADM, the add and drop wavelengths are fixed beforehand while in dynamic mode, OADM can be set to any wavelength after installation. Passive OADM uses fiber optic filters, fiber gratings, and planar waveguides in networks with WDM systems. Dynamic OADM can select any wavelength by provisioning on demand without changing its physical configuration. It is also less expensive and more flexible than passive OADM. Dynamic OADM is separated into two generations.

A typical OADM consists of three stages: an optical demultiplexer, an optical multiplexer, and between them a method of reconfiguring the paths between the optical demultiplexer, the optical multiplexer and a set of ports for adding and dropping signals. The optical demultiplexer separates wavelengths in an input fiber onto ports. The reconfiguration can be achieved by a cross connect patch panel or by optical switches which direct the wavelengths to the optical multiplexer or to drop ports. The optical multiplexer multiplexes the wavelength channels that are to continue on from demultipexer ports with those from the add ports, onto a single output fiber.

Physically, there are several ways to realize an OADM. There are a variety of demultiplexer and multiplexer technologies including thin film filters, fiber Bragg gratings with optical circulators, free space grating devices and integrated planar arrayed waveguide gratings. The switching or reconfiguration functions range from the manual fiber patch panel to a variety of switching technologies including microelectromechanical systems (MEMS), liquid crystal and thermo-optic switches in planar waveguide circuits.

CWDM and DWDM OADM provide data access for intermediate network devices along a shared optical media network path. Regardless of the network topology, OADM access points allow design flexibility to communicate to locations along the fiber path. CWDM OADM provides the ability to add or drop a single wavelength or multi-wavelengths from a fully multiplexed optical signal. This permits intermediate locations between remote sites to access the common, point-to-point fiber message linking them. Wavelengths not dropped, pass-through the OADM and keep on in the direction of the remote site. Additional selected wavelengths can be added or dropped by successive OADMS as needed.

FiberStore provides a wide selection of specialized OADMs for WDM system. Custom WDM solutions are also available for applications beyond the current product designs including mixed combinations of CWDM and DWDM.