Design and Research of Intelligent SFP optical module

by Fiber-MART.COM

Introduction

 

In the optical communication products, optical module occupies has a very important position. Optical transceiver module as one of the key technologies of optical fiber communication network, is widely used in synchronous optical network SONET) and Synchronous Digital Hierarchy SDH), Asynchronous Transfer Mode (ATM), Fiber Distributed Data Interface (FDDI), as well as Fast Ethernet and thousands Gigabit Ethernet and other systems.

 

In the present optical communication products, fiber optic transceiver module has been more popular than others, SFP GBIC module module volume ratio reduced by half, but also supports hot-swap capabilities, has been widely used. Meanwhile, in the various existing networks needed optical transceiver module types, more and more requirements are also increasing. To meet the ever increasing performance requirements of the system,Optical module continues to develop intelligent, fast and high-density interconnect direction.

 

Intelligent SFP optical modules, namely USES the fiber optic sfp module of digital diagnosis function, will become a new generation of optical transceiver module integrated in the window.It can realize network management unit real-time monitoring the temperature of the transceiver module, power supply voltage, bias current, as well as the transmitting and receiving optical power.Through monitoring of these parameters, we can help system administrators predict the life of the light module, fault isolation system and authentication module in the installation of compatibility, etc.

 

A smart SFP optical module system design

 

1.1

 

Transmitting section

 

The main role of the light-emitting process in the optical transmission module is to convert the optical signal into an electrical pulse signal is a pulse, the electrical signal is input, the output optical signal. Transmitter module, mainly by the laser driving circuit and the TOSA. Which TOSA backlit by the laser diode LD and PD components. LD is used in vertical cavity surface emitting laser VCSEL.

 

First electrical modulation of the laser drive lasers to meet the input digital fiber optic communications system required drive signal, the drive signal from the bias current Ibias And the modulation current Imod composition, the laser emits an optical signal corresponding to the driving of the driving signal, the optical signal is coupled into the optical fiber and transmitted to the receiving end. In this scenario, the laser driver selection MAX3286.

 

Laser driver with the functions of automatic power control (APC), APC circuit using the backlight diode in the TOSA, monitoring laser the size of the backlight.When the optical power is less than one rating, through increase the drive current feedback circuit, laser output power increases as the rated power value.Conversely, if the optical power is greater than a certain rating, is through feedback circuit reduce drive current, laser power output is less.APC circuit can dynamically adjust the laser power, therefore, the size of the bias current, can automatically compensate laser due to the change of ambient temperature or aging caused by the change of the output optical power, keep the output optical power range is relatively stable.

 

 

Receiving part

 

The main role of the receiver module is attenuated after

 

deformation weak optical fiber cable transmission signal to a pulse electric pulse signal by photoelectric conversion, and give sufficient amplification, a standard reduction of the digital pulse signal. Optical receiver module schematic shown mainly by the photodiode PD, a preamplifier, a limiting amplifier and other components. Which photodiode and preamp integrated package together constitute ROSA.

 

A photodiode is a core device of a digital optical receiver, an optical pulse signal will be the electrical pulse signal by photoelectric conversion, commonly used are PIN photodiodes and avalanche photodiode APD. Optical signal from the optical interface enters the photodiode PD, is converted into a weak current, the current through the pre-amplifier and converted into a voltage level is amplified to an appropriate level.

 

Effect limiting amplifier output of the preamplifier is the magnitude of different amplitude analog signal into a digital signal, these signals can be amplified. To photoelectric detectors with a good match and get the low-noise and wide-band preamplifier gain is not too high, the preamplifier output voltage amplitude is usually from a few millivolts to tens of millivolts, such small signals can not be directly output optical module is therefore necessary to further enlarge the signal; the other hand, the photodetector detects the light signal from the amplitude of the current signal in a defined tolerance level, the tolerance limits of the capacity of the fiber considered Poor, splice loss and the parameter fluctuations caused by temperature and aging, however, the data for further processing, the signal amplitude is preferably a constant value.

 

Therefore, limiting amplifier requires a certain dynamic range, which usually requires a dynamic range of more than 20dB.

 

1.3

 

Digital Diagnostics DDM part

 

Digital diagnostics mainly composed of MCU to complete. By temperature MCU, the network management unit may receive real-time monitoring module, the power supply voltage, laser bias current and the light emitting and receiving power. By measuring these parameters, the management unit can quickly identify the specific location of fiber link failure occurs, simplify maintenance, improve system reliability.

 

Five DDM parameter acquisition circuit for acquisition by the first conversion, the inputs to the ADC, ADC five circuit analog voltage into a digital signal sent by the decoder circuit is stored in a memory support DDM corresponding address bit . Transmission of information via a two-wire serial interface (SCL clock line and data line SDA) to achieve.

Fiber Splitter for FTTH Applications

Passive optical network (PON) has been widely applied in the construction of FTTH (fiber to the home). With PON architecture, network service providers can send the signal to multiple users through a single optical fiber, which can help them save great costs. To build the PON architecture, optical fiber splitter is necessary.

 

What Is Fiber Splitter?

The fiber splitter is a passive component specially designed for PON networks. Fiber splitter is generally a two-way passive equipment with one or two input ports and several output ports (from 2 to 64). Fiber splitter is used to split the optical signal into several outputs by a certain ratio. If the ratio of a splitter is 1×8 , then the signal will be divided into 8 fiber optic lights by equal ratio and each beam is 1/8 of the original source. The splitter can be designed for a specific wavelength, or works with wavelengths (from 1260 nm to 1620 nm) commonly used in optical transmission. Since fiber splitter is a passive device, it can provide high reliability for FTTH network. Based on the production principle, fiber splitters include Planar Lightwave Circuit (PLC) and Fused Bionic Taper (FBT).

 

PLC Splitters

PLC splitters are produced by planar technology. PLC splitters use silica optical waveguide technology to distribute optical signals from central office to multiple premise locations. The output ports of PLC splitters can be at most 64. This type of splitters is mainly used for network with more users.

 

The Structure of PLC splitters

Internal Structure

 

The following figure shows a PLC splitter. The optical fiber is splitted into 32 outputs. PLC chip is made of silica glass embedded with optical waveguide. The waveguide has three branches of optical channels. When the light guided through the channels, it is equally divided into multiple lights (up to 64) and transmitted via output ports.

 

1x32-plc-splitter

 

Outside Configuration

 

Bare splitter is the basic component of PLC fiber splitter. For better protection of the fragile fiber and optimized use, PLC splitters are often equipped with loose tube, connector and covering box. PLC splitters are made in several different configurations, including ABS, LGX box, Mini Plug-in type, Tray type, 1U Rack mount, etc. For example, 1RU rack mount PLC splitter (as shown in the figure below) is designed for high density fiber optical distribution networks. It can provide super optical performance and fast installation. This splitter is preassembled and fibers are terminated with SC connectors. It’s ready for immediate installation.

 

rack-mount-plc-spllitter

 

FBT Splitters

FBT splitters are made by connecting the optical fibers at high temperature and pressure. When the fiber coats are melted and connected, fiber cores get close to each other. Then two or more optical fibers are bound together and put on a fused taper fiber device. Fibers are drawn out according to the output ratio from one single fiber as the input. FBT splitters are mostly used for passive networks where the split configuration is smaller.

 

PLC Splitters From fiber-mart.COM

Fiberstore offers a wide range of PLC splitters that can be configured with 1xN and 2xN. Our splitters are designed for different applications, configurations including LGX, ABS box with pigtail, bare, blockless, rack mount package and so on.

An Easy Guide to MPO/MTP Polarity

Nowadays, many data centers are migrating into the 40G and 100G transmission. To prepare for this change, MPO/MTP technology is applied to meet the requirements of high density patching. Typically, a fiber optic link needs two fibers for full duplex communications. Thus the equipment on the link should be connected properly at each end. However, high density connectivity usually requires more than two fibers in a link, which makes it more complex to maintain the correct polarity across a fiber network, especially when using multi-fiber MPO/MTP components for high data rate transmission. Therefore, many technicians would prefer to use pre-terminated MPO/MTP components designed with polarity maintenance for easier installation. This article will specifically guide you to understand the polarity of MPO/MTP products and the common polarization connectivity solutions.

What Is Polarity?

Keeping the right polarity is essential to the network. A transmit signal from any type of active equipment will be directed to the receive port of a second piece of active equipment and vice versa. Polarity is the term used in the TIA-568 standard to explain how to make sure each transmitter is correctly connected to a receiver on the other end of a multi-fiber cable. Once the component is connected to the wrong polarity, the transmission process will be unable to go on.

Structure of MPO/MTP Connector

When discussing about the polarity, MPO/MTP connector is an important component for you to know. An MPO/MTP connector has a key on one side of the connector body. There are two positions of the key – key up or key down. Key up position means that the key sits on top. When the key sits on the bottom, it is the key down position. Moreover, the fiber holes in the connector are numbered in sequence from left to right named as P1 (position 1), P2, etc. Each connector is additionally marked with a white dot on the connector body to designate the P1 side of the connector when it is plugged in. The MPO/MTP connector can be further divided into female connector and male connector. The former has no pins while the latter has two pins on the connector. The following picture shows the basic structure of MPO/MTP connector.

structure-of-mpo-connector

Connecting Methods of A, B, C

The TIA standard defines two types of duplex fiber patch cables terminated with LC or SC connectors to complete an end-to-end fiber duplex connection: A-to-A type patch cable is a cross version and A-to-B type patch cable is a straight-through version. Based on this, there are three polarity connecting methods for MPO/MTP products. Here will introduce them in details.

duplex-patch-cable

Method A is the most straight-forward method. It uses straight-through patch cords (A-to-B) on one end that connect through a cassette (LC-to-MPO or SC-to-MPO depends on what the equipment connector is), a straight-through MPO/MTP key up to key down backbone cable and a “cross-over” patch cord (A-to-A) at the other end.

method-a

Method B is the “cross-over” occurred in the cassette. The keys on the MPO cable connectors are in an up position at both ends, but the fiber that is at connector P1 in one end is in P12 at the opposite end, and the fiber that is in P12 at the originating end is in P1 at the opposing end. Only A-to-B type patch cord is needed for this method.

method-b

Method C is the most complicated. There is pair-wise “cross-over” in the backbone cable. A-to-B patch cords are used on both ends. The cassette uses MPO/MTP key up to key down and the backbone cable is pair-wise flipped so P1, P2 connects to P2, P1 and P3, P4 connects to P4, P3, etc.

method-c

Conclusion

Knowing the polarity of MPO/MTP system helps you better upgrade the 40G and 100G networks. According to different polarity methods, choosing the right MPO/MTP patch cables , connectors and cassettes will provide greater flexibility and reliability for your high density network.

Optical divider and connector market strong demand

In many related policies, driven by large-scale light in to the copper retreat has unfolded, with FTTx substantive, ODN products becoming an important part of FTTx system, may also be the expansion opportunity.

In line with the statistics, the proportion of ODN access equipment investment taken into account 50% ~ 60% of FTTx equipment investment.Could be predicted the years in the future our country ODN access device how big the marketplace will keep growth trend in excess of 20%, to 2012, how large the marketplace is predicted to attain 14.55 billion yuan.ODN access products are usually made from optical divider, optical connector and also the equipments install these elements (housing, terminal box,etc.).ODN core technology is mainly manifested within the optical divider, optical connector, passive optical components products.

Bypass the marketplace popular

PLC (planar optical waveguide technology) optical divider is primarily utilized in FTTH user access network, global curiosity about PLC optical divider in ’09 about3300 wantong, annual rate of development of 32%.Global markets presents different pattern in various area, Japan, Columbia following a curiosity about high-speeddevelopment for quite a while, has become approaching the gentle, demand is pretty stable, makes up about about 50 % from the share of the market;The outcome from theeconomic crisis in the usa, influenced by a specific momentum;And developing countries for example China, India, Brazil’s FTTx a fast-growing construction phase, thusend up being the main growth reason behind the marketplace.

Using the development of our country FTTx, planar optical waveguide technologies have get to be the growth and development of optical communication industry.PLC marketa hot, many are very bullish on passive optical device manufacturers, will be ready to mount the PLC program.Right now, the PLC in the leading manufacturers of opticalcommunication technology, rich and rich science, and science, etc.

PLC products around the massive in China telecom and China unicom bidding, driven by domestic PLC market, an order income growth is powerful.Through the 12th five-yearplan, operators will accelerate the FTTx network deployment, that will effectively promote the domestic market requirement for passive components, PLC products sincethe core device of FTTx, will get a large amount of applications, inside the global share of the market is predicted to assist enhance.

PLC could be the core from the optical divider chip, the chip is essential to produce and manufacture.Recently, we’ve already had some light components enterprisessuccessfully on PLC chip encapsulation, most foreign enterprises also transfer chips to the country to encapsulate, these conditions to build up PLC optical dividerindustry has built favorable conditions.

The connector has huge potential

Requirement of global optical connector in 2008 to 2008, increased by 11% in the year earlier, last year to a single.04 billion.The downstream applications for instance communication, optical network market demand growth, the influence of is anticipated to achieve 1.63 billion by 2012.

Global optical connector within the consumer market, the American companies are the largest.The oldest along with the future development potential may be the Asia Pacific markets.While using advancement of optical fiber cable technology increase the risk for optical fiber gets closer and nearer to the final outcome user, the shorter links, including board interconnection relating to the needs in the growing, thus promoted greatly rise in the quantity of the connector.

This season countries for the policy within the development and integration of optical communication industry will heighten the size the domestic market of optical fiber connector, promote the introduction of domestic optical fiber connector industry.Domestic industry restructuring and three g licensing as well as other factors to market regarding the optical communication network, the resulting including light to the copper back, “FTTx” and so on the most recent market demand, is a big market possibility of optical fiber connector.

Based on China electronics industry association information center, 2009, 280 million optical fiber connector in the domestic market demand, domestic optical fiber connector from 2010 to 2015 how large industry demand will probably be around 12.6% growth, demand will reach 2012, 410 million.As fiber optic broadband network large-scale construction start, therefore, three major telecom operators entry to the building construction is anticipated being orderly development of optical network, optical fiber connector market scale continuously grow.

The principle of optical fiber connector and classification

In optical fiber communication (transmission) link, in order to achieve the different modules.The needs of the flexible connection between devices and systems, there must be a able to removable between optical fiber and optical fiber (activities) of the connection device, can make the light path according to the required transmission channel, with the purpose of the implementation and complete reservation or expectations and requirements, can realize the function of the device is called a connector.Optical fiber connector is the fiber of two surface precision docking, so that the optical output of light energy to maximize the coupling to the receiving optical fiber, and optical link due to the intervention and to minimize the effects on the system, it is the basic requirement of optical fiber connector.To a certain extent, optical fiber connector also affects the reliability and the performance of optical transmission system.

A.Is the main optical fiber connection

1. The fixed connection.Mainly used for permanent connection between optical fiber in optical fiber cable line, with welding, also have use bonding and mechanical connection.Is characterized by low coupling loss, high mechanical strength.Equipment need welding machine, probably thousands of dollars.

2. Active connection.Is mainly used in optical fiber transmission system equipment and instrument connections between, mainly through the optical coupler plug connection.Is characterized by flexible joint is better, exchange connection is convenient, large loss and reflection is the lack of this connection.Now the insertion loss is already very good, dozens of RMB is ok, you can directly buy finished product, if you want to bulk, also need to face polishing grinding equipment, that is too expensive, suggested that direct buy jump line.

3. A temporary connection.Measure the tail fiber and measured coupling between optical fiber connection, connected by this method.Characteristic is convenient and flexible, low cost, low requirements for loss, temporary measure when use this way to connect more.Also can use welding machine or V groove with glue.

B. To optical fiber connection request

1. The requirements for fixed connection Optical fiber fixed connection cable line is a key technology.Demand for fixed connection has the following several aspects: coupling loss is small, good consistency;Coupling loss stability is better, general difference in temperature range should not have the generation of additional loss;Has enough mechanical strength and service life;Operation should be simple, easy to construction work;Joint to small volume, easy to place and protection;Low cost, material is easy to be processed.

2. The requirement of active connection For removable optical fiber connection, are now using mechanical connector.The requirement basically has the following several aspects: connection loss, single-mode fiber loss is less than 0.5 dB;Should have good repeatability and interchangeability.After repeatedly plug and interchangeable parts, there is still a good consistency;Has good stability, fittings insertion loss stability after fastening, not affected by temperature change;Smaller volume, weight light;Have certain strength;The price is suitable.

3. Optical fiber temporary connection to temporary connection request, also can use the welding machine welding.Require low loss as much as possible, in connection with V groove and capillary, must add liquid ratio, otherwise unable to eliminate the Fresnel reflection.3. Optical fiber connection loss factor

C.Optical fiber connection loss factor

After the fiber connection, light through joint parts will produce certain loss, known as optical fiber connecting the transmission loss, the splicing loss.The main analysis of single-mode fiber coupling loss factor.

1. The intrinsic factors on the connection is most affected by single mode optical fiber mode field diameter.When 20% of mode field diameter mismatch, will produce 0.2 dB over the loss.As far as possible the use of optical fiber mode field diameter smaller, to reduce the loss of connection has the vital significance.

2. The external factors outside the main factors of single-mode optical fiber connection loss for the axis displacement and axial tilt.For mechanical connection with vertical to the weld and the fiber core deformation and other factors.
(1) axis misalignment.When the dislocation at 1.2 microns, cause the loss of 0.5 dB, connected to the positioning accuracy, can effectively control the influence of the axial displacement.
(2) the axial tilt.When the tilt reaches 1 °, will cause a loss of 0.2 dB.Selects the high quality fiber cutting knife, can improve the axial tilt caused by wear and tear.
(3) the fiber core deformation.When the amount of current, advancing the automatic welding machine, discharge current, time set reasonable, such as fiber core deformation caused by the wastage can do below 0.02 dB.

D. Optical fiber connection method and comparison

1. The welding machine welding This method is mainly used for optical fiber joint connection, is currently used more in automatic welding machine for welding, welding machine points single core and multicore welding machine two kinds.Before formally succeeded, welding machine, the experiments of various parameters to determine the alignment precision of welding machine, discharge size, the quantity of various parameters, such as, to adapt it to the concrete in the specific working conditions of the fiber, the loss of control within a set of indicators.Succeeded completed, should be timely optical time-domain reflectometer to determine the loss, after the loss conform to the requirements of the indicators, before being reinforcing process, until the complete connection.
2. Mechanical connection By far the most common connection characteristics of three types of mechanical connector is as follows: process FO type connector.This kind of optical fiber connector is standard connection form of single core optical fiber.Most of the current product end face grinding to turn it into a ball, the convergence of the beams using optics refraction principle, reduce the loss of the connection.This kind of optical fiber connector multi-purpose on optical fiber distribution frame and test instrument, for transfer.NTT multicore fiber optic connectors.This kind of optical fiber connector can be connected a 12 optical fibers, has a large capacity, simple manufacturing process, and in place of low loss, therefore, in less demanding users to connect optical fiber has been widely used.This method used in optical fiber short distance relay, relay and users, the effect is better.Wire connector.With the development of technology, wiring son can do 0.1 dB below the average in loss and 50% of the splicing loss can be below 0.05 dB, adaptability to the environment temperature and humidity is relatively good.Due to this kind of connection method does not require expensive welding machine, and a single core and multicore specifications, convenient use and expects its prospect of application is more and more wide, make the connection of the fiber as convenient as cable.In the development of optical fiber communication technology is critical.Simplify the connection technology, improve the quality of connection, to expand fiber applications will play a positive role in promoting.

The proper way to store cables

We’ve all experienced it. The crushing dread of pulling out a cable that you need to not only to find that it is a tangled mess but then discover that it no longer works. This can be the nightmare of anyone that works in an industry that relies on wires and cables to help keep equipment working. No matter if you work in audio, video or simply just want cables that you can rely on in order to enjoy media on your devices, having nicely kept cables not only looks great, but can prolong the life of this much needed resource.

One of the big problems with cables is that they can so easily get tangled. Long lengths of wire can be very unwieldy and can be hard to take the time to pack up and secure for future use. Many people who depend on these cords usually do not have the time to devote to standing in one place for long periods of time, wrapping a cord up in their hands. However, the importance of proper cable storage and maintenance should not be underestimated. A properly wrapped cable has the ability to last longer than one that is abused and hastily shoved into a drawer, box or case.

 

Many people are not aware of techniques that can help them save their cables. If a cable is stored improperly or wound the wrong way, it can fray on the inside and can cause damage, leading to the cable malfunctioning. Luckily, learning the proper way to wind and store a cable is very easy. One of the best ways to get started is to simply make a simple loop with the cord in your hand. Then make a loop around in the opposite direction, creating another circle, and coming out in the same place over the fingers again, but inverted. This will reduce the fraying on the inside of the wire and will help prolong the life of the wire. An added benefit is that the cable will not get tangled and all that is needed to unravel it is just to simply start unwinding. The wire will then unravel straight.

However, in order to keep the wire in this form and in order to store it, first leave enough length at the end of the wire in order to thread it through the circle. Then, continue to wrap it around the outside of the circle and through again to the inside, creating a spiral covering the outside of the circle and keeping all of the parts in place.

 

Another great way to wind and store a cable is to start like the above example, but instead of creating a spiral at the end, create a circle at the start and then start a spiral until you run out of wire. This also has the added benefit of shortening the cord so that it takes up less room when in use. Both of the above examples are great ways you can use to help prolong the life of your cables and store them in a quick and easy way.