Category: Fiber Transceivers

More than a dozen types of fiber optic connectors have been developed by various manufacturers since 1980s. Although the mechanical design varies a lot among different connector types, the most common elements in a fiber connector can be summarized in the following picture. The example shown is a SC connector which was developed by NTT (Nippon Telegraph and Telephone) of Japan.

1. The fiber ferrule.

SC Connector Fiber Ferrule

SC connector is built around a long cylindrical 2.5mm diameter ferrule, made of ceramic (zirconia) or metal (stainless alloy). A 124~127um diameter high precision hole is drilled in the center of the ferrule, where stripped bare fiber is inserted through and usually bonded by epoxy or adhesive. The end of the fiber is at the end of the ferrule, where it typically is polished smooth.

2. The connector sub-assembly body.

The ferrule is then assembled in the SC sub-assembly body which has mechanisms to hold the cable and fiber in place. The end of the ferrule protrudes out of the sub-assembly body to mate with another SC connector inside a mating sleeve (also called adapter or coupler).

3. The connector housing

Connector sub-assembly body is then assembled together with the connector housing. Connector housing provides the mechanism for snapping into a mating sleeve (adapter) and hold the connector in place.

4. The fiber cable

Fiber cable and strength member (aramid yarn or Kevlar) are crimped onto the connector sub-assembly body with a crimp eyelet. This provides the strength for mechanical handing of the connector without putting stress on the fiber itself.

5. The stress relief boot.

Stress relief boot covers the joint between connector body and fiber cable and protects fiber cable from mechanical damage. Stress relief boot designs are different for 900um tight buffered fiber and 1.6mm~3mm fiber cable.

A systems analysis continues to be completed to consider dynamical transient effects in the physical layer of an Optical WDM Network. The physical layer dynamics include effects on different time scales. Dynamics from the transmission signal impulses possess a scale of picoseconds. The timing recovery loops in the receivers be employed in the nanoseconds time scale. Optical packet switching in the future networks will have microsecond time scale. Growth and development of such optical networks is yet continuing. Most of the advanced development work in optical WDM networks is presently focused on circuit switching networks, where lightpath change events (for example wavelength add/drop or cross-connect configuration changes) happen on the time scale of seconds.

It is focused on the dynamics from the average transmission power associated with the gain dynamics in Optical Line Amplifiers (OLA). These dynamics may be triggered by the circuit switching events and have millisecond time scale primarily defined by the Amplified Spontaneous Emission (ASE) kinetics in Erbium-Doped Fiber Amplifiers (EDFAs). The transmission power dynamics will also be influenced by other active components of optical network, for example automatically tunable 100GHz DWDM, spectral power equalizers, or other light processing components. When it comes to these dynamics, a typical power of the lightpath transmission signal is recognized as. High bandwidth modulation from the signal, which actually consists of separate information carrying pulses, is mostly ignored.

14_nodes Ring WDMRing WDM networks implementing communication between two fixed points are very well established technology, in particular, for carrying SONET over the WDM. Such simple networks with fixed WDM lighpaths happen to be analyzed in many detail. Fairly detailed first principle models for transmission power dynamics exist for such networks. These models are implemented in industrial software allowing engineering design calculations and dynamical simulation of these networks. Such models could possibly have very high fidelity, but their setup, tuning (model parameter identification) and exhaustive simulations covering a variety of transmission regimes are potentially very labor intensive. Adding description of new network components to such model could need a major effort.

14_nodes Mesh WDMThe problems with detailed first principle models is going to be greatly exacerbated for future Mesh WDM networks. The near future core optical networks will be transparent to wavelength signals on a physical layer. In such network, each wavelength signal travels through the optical core between electronic IP routers around the optical network edge using the information contents unchanged. The signal power is attenuated in the passive network elements and boosted by the optical amplifiers. The lightpaths is going to be dynamically provisioned by Optical Cross-Connects (OXCs), routers, or switches independently on the underlying protocol for data transmission. Such network is basically a circuit switched network. It might experience complex transient processes of the average transmission power for every wavelength signal at the event of the lightpath add, drop, or re-routing. A mix of the signal propagation delay and channel cross-coupling might result in the transmission power disturbances propagating across the network in closed loops and causing stamina oscillations. Such oscillations were observed experimentally. Additionally, the transmission power and amplifier gain transients could be excited by changes in the average signal power because of the network traffic burstliness. If for some period of time the wavelength channel bandwidth is not fully utilized, this could result in a loss of the average power (average temporal density of the transmitted information pulses).

First circuit switched optical networks are already being designed and deployed. Fraxel treatments develops rapidly for metro area and long term networks. Engineering design of circuit switched networks is complicated because performance has to be guaranteed for all possible combinations of the lightpaths. Further, as such networks develop and grow, they potentially need to combine heterogenous equipment from a variety of vendors. A system integrator (e.g., Fiber-mart.com) of such network might be different from subsystems or component manufacturer. This creates a necessity of developing adequate means of transmission power dynamics calculations which are suitable for the circuit switched network business. Ideally, these methods should be modular, independent on the network complexity, and use specifications on the component/subsystem level.

Fiber-mart.com has technical approach to systems analysis that’s to linearize the nonlinear system around a fixed regime, describe the nonlinearity like a model uncertainty, and apply robust analysis that guarantees stability and gratifaction conditions within the presence of the uncertainty. For a user of the approach, there is no need to understand the derivation and system analysis technicalities. The obtained results are very simple and relate performance to basic specifications of the network components. These specifications are somewhat not the same as those widely used in the industry, but could be defined from simple experimentation using the components and subsystems. The obtained specification requirements may be used in growth and development of optical amplifiers, equalizers, optical attenuators, other transmission signal conditioning devices, OADM Modules, OXCs, and any other optical network devices and subsystems influencing the transmission power.

With the continuous progress of science and technology, the Internet has gradually gone into the homes of the ordinary people, and the speed of broadband has increasingly become the topic of people in the entertainment and work often, from narrowband dial-up to broadband Internet, and then the fiber access Internet, broadband network, the rapid pace of PON technology gradually come to the front. Currently, there are two quite compelling PON standard has been officially released, which are GPON standard developed by the ITU / FSAN and EPON standard developed by IEEE 802.3ah working group. PON technology has been no doubt the ultimate solution for the future FTTH era. EPON and GPON who will the dominant FTTH tide has become a new hot debate. What’s the difference between EPON and GPON?

GPON and EPON Differences

Perhaps the most dramatic distinction between the two protocols is a marked difference in architectural approach. GPON provides three Layer 2 networks: ATM for voice, Ethernet for data, and proprietary encapsulation for voice. EPON, on the other hand, employs a single Layer 2 network that uses IP to carry data, voice, and video.

A multiprotocol transport solution supports the GPON structure (Figure 1). Using ATM technology, virtual circuits are provisioned for different types of services sent from a central office location primarily to business end users. This type of transport provides high-quality service, but involves significant overhead because virtual circuits need to be provisioned for each type of service. Additionally, GPON equipment requires multiple protocol conversions, segmentation and reassembly (SAR), virtual channel (VC) termination and point-to-point protocol (PPP).

EPON provides seamless connectivity for any type of IP-based or other “packetized” “communications” (Figure 2). Since Ethernet devices are ubiquitous from the home network all the way through to regional, national and worldwide backbone networks, implementation of EPONs can be highly cost-effective. Furthermore, based on continuing advances in the transfer rate of Ethernet-based transport — now up to 10 Gigabit Ethernet — EPON service levels for customers are scalable from T1 (1.5 Mbit/s) up through 1 Gbit/s.

Upstream Bandwidth

Subtracting the various system run overhead from the total bandwidth of the system uplink transmission is the upstream available bandwidth. It has a great relationship with the number of the ONU contained in the system, DBA (Dynamic Bandwidth Allocation) algorithm polling cycle, the type of bearer services, as well as the various business proportion. EPON and GPON are broadband access technology, hosted business IP data services. Below we will calculate the uplink the beared pure IP services available bandwidth of EPON and GPON that contain 32 ONUs, fiber optic coupler,the case of polling period 750s.

EPON

EPON upstream rate is 1.25 Gbit/s. Because the 8B/10B line coding, each 10bit are 8bit valid data, so its effective upstream transmission bandwidth is 1 Gbit/s. EPON upstream overhead of running the system and its proportion of the total bandwidth are as following:

1. Used for the the burst reception of physical layer overhead: about 3.5%;

2. Ethernet frame encapsulation overhead: about 7.4%;

3. MPCP (Multi-Point Control Protocol) and OAM operation and management of maintenance protocol overhead: about 2.9%;

4. DBA algorithm resulting in the remaining time slots (that is not sufficient to transfer a complete Ethernet frame time slot) wasted: about 0.6%;

5. EPON upstream total overhead is all of the above about 144 Mbit/s, the available bandwidth is about 856 Mbit/s.

GPON

GPON supports a variety of rate levels, has asymmetric rate that downlink is 2.5Gbps or 1.25Gbps, the upgoing is 1.25Gbps or 622 Mbps. NRZ encoding the uplink total bandwidth for 1.244 Gbit/s, GPON upstream overhead of running the system as following:

1. The proportion of its total bandwidth is used for the the burst reception of physical layer overhead: about 2.0%;

2. GEM (GPON encapsulation method) frame and the Ethernet frame encapsulation overhead: about 5.8%;

3. The PLOAM (physical layer operation, management and maintenance) protocol overhead: about 2.1%;

4. Remaining slots of the DBA algorithm introduced the additional encapsulation overhead: about 0.8%.

5. GPON upstream total overhead is all of the above about 133 Mbit/s, the available bandwidth about 1111 Mbit/s.

A fiber-optic multiplexer is a device that processes two or more light signals through a single optical fiber, in order to increase the amount of information that can be carried through a network. Light wavelengths are narrow beams that ricochet through reflective optical tubing, sometimes over long distances, to provide instantaneous electronic signal processing at the speed of light. Multiplexers work by increasing a fiber’s transmission capacity using different techniques and light source technologies. When the signal arrives at its destination, a demultiplexer separates the data streams. Using a multiplexer also allows data to be sent farther, more securely, and with less electromagnetic and radio frequency interference.

Also known as a mux, the fiber-optic multiplexer saves time and cost by squeezing more information through the optical network pathway. It is possible to split signals by varying the schedule or period of each transmission. Time Division Multiplexing (TDM) combines multiple signals by rapidly alternating between them so that only one is transmitting at any given time. Statistical Time Division Multiplexing (STDM) assigns each signal a specific time slot in order to optimize bandwidth usage. Further techniques include divisions of wavelength and frequency.

Wavelength Division Multiplexing (WDM) utilizes the total available pass band of an optical fiber. It assigns individual information streams different wavelengths, or portions of the electromagnetic spectrum. Similarly, Frequency Division Multiplexing (FDM) assigns each signal a different frequency. Carrier frequencies contain the signal while unused guard frequencies provide buffering to reduce interference. This helps minimize audible and visual noise and preserves the integrity of the original signal throughout the network.

Fiber-optic multiplexer technology serves single-mode and multimode optical fibers with multichannel rack mount or standalone units. This makes mixing channels with different configurations possible for a range of interface combinations. These devices provide stronger, more reliable transmissions in areas that have a lot of electromagnetic, radio frequency, or lightning interference.

As technology improves and information needs grow to fill the capacities of existing networks, equipment such as the fiber-optic multiplexer lessens the need to upgrade the fiber-optic infrastructure itself. Multiplexers permit new configurations of transmission protocols by increasing the amount of wavelengths or frequencies of light signals. By upgrading repeaters and terminal equipment, existing network transmission capacity can expand with demand.

Used by cellular carriers, Internet service providers, public utilities, and businesses, fiber-optic multiplexer technology extends the reach and power of telecommunications technologies. Network management systems allow for system service and maintenance, and provide for security, fault management, and system configuration. With advantages like lower costs and longer life expectancies, current fiber-optical networks are aided by improvements in multiplexing technology, and may provide light speed data transmission well into the future.

Optical networks require signal being splitted somewhere in design to serve for multiple customers. Splitter technology has made a huge step forward in the past few years by introducing PLC (Planar Lightwave Circuit) splitter. It has proven itself as a higher reliable type of device compared to the traditional FBT (Fused Biconical Taper) splitter. While being similar in size and outer appearance, both types of splitters provide data and video access for business and private customers. However, internally the technologies behind these types vary, thus giving  service providers a possibility to choose a more appropriate solution.

FBT splitter is made out of materials that are easily available, for example steel, fiber, hot dorm and others. All of these materials are low-price, which determines the low cost of the device itself. The technology of the device manufacturing is relatively simple, which has the impact on its price as well. In scenario where multiple splits are needed, the size of the device may become an issue. It is important to keep in mind that splitters are being deployed in the fields either in cabinets or in strand mountings, so the size of device plays a critical role. FBT splitters only support three wavelengths (850/1310/1550 nm) which makes these devices unable to operate on other wavelengths. Inability of adjusting wavelengths makes FBT splitters less customizable for different purposes. Moreover, the devices are to a high extent temperature sensitive, providing a stable working range of -5 to 75 C. In certain areas, such as Scandinavian countries this temperature restrictions may be crucial. The signal processed by FBT splitters cannot be splitted evenly due to lack of management of the signals

PLC splitter manufacturing technology is more complex. It uses semiconductor technology (lithography, etching, developer technology) production, hence it is more difficult to manufacture. Therefore, the price of the device is higher. However, there is a number of advantages the device possesses. The size of the device is compact, compared to FBT splitters, making it suitable for density applications. PLC splitter operates at wider temperature range (-40 to 85 C), allowing its deploying in the areas of extreme climate. The split ratio goes up to 64, providing a high reliability. Furthermore, the signal can be split equally due to technology implemented. A range of wavelengths (1260 – 1650 nm) is provided, so the wavelengths are adjustable. Critical points of the device that might fail are input and output, so the general risk of failure is low.

The CWDM are by and large in view of thin coat channel innovation which is the type of item fall under the WDM class. There arrived in a total scope of Class-8 CWDM Mux-Demuxand also OADM that stands for Optical Add Drop Multiplexer units with a specific end goal to meet a wide range of necessities and system arrangements.

Likewise, it has across the board applications that require the Channel CWDM. Some of them include: Gigabit and 10G Ethernet, Fiber Channel, ATM, ESCON, in Metro total, SDH/SONET, and CATV and so forth. Presently, we should talk about the accompanying components and utilizations of Channel CWDM that settle on it an ideal decision for all. The CWDM Mux / Demux items give up to 16-channel or even 18-channel Multiplexing on a solitary fiber. Standard CWDM Mux/Demux bundle sort include: ABS box bundle, LGX pakcage and 19″ 1U rackmount.

Highlights

The loss of insertion quality creates from the presentation of a gadget into the optical fiber is by and large lesser in CWDM than alternate gadgets; this produces short inclusion costs.

Channel-8 CWDM is dependably very steady and solid in the meantime. Not at all like every other sort of WDM class, the Channel CWDM has higher dependability.

The CWDM items are typically Epoxy free on optical way; this prompts better working and Epoxy free condition while the execution.

In CWDM, the channel segregation is very high. This expanded seclusion prompts better and successful outcomes.

Applications

WDM and Access Organize: As these channel sorts are the piece of WDM class, these have their best application in the WDM and also Access systems.

Line Observing: These items have their incredible use in line checking. This guarantees there is no crash on a similar line of some other range or frequency.

Cellular Application: The CWDM channel arrangements have their utilizations and applications additionally in the Cellular area, and advances as the unequaled panacea for some different parts and ventures.

Telecommunication: The broadcast communications devours Channel-8 CWDM at an incredible rate. It needs to utilize these items for the straightforward transmission of signs and utilization of the filaments for the same.

Aside from every one of the elements and applications, the capacity of CWDM is additionally to unravel the deficiency of fiber and straightforward transmission of exchange while lessening the charges of system building. This is the motivation behind why the Channel CWDM and LGX CWDM Mux and DeMux Module have a matter of extraordinary heights in the realm of fiber optics, flag transmission and multiplexing and so forth.