Product category:
Optical Filters, Lenses, Gratings etc
News Release from: Southampton Photonics | Subject: BragNet
Edited by the Electronicstalk Editorial
Team on 12 July 2001
Fibre Bragg gratings increase channel
capacity
Southampton Photonics has formally launched its BragNet family of fibre Bragg gratings, claimed to be the most advanced of their type.
Next-generation fibre-optic components and subsystems vendor, Southampton Photonics (SPI), has formally launched its BragNet family of fibre Bragg gratings (FBGs), claimed to be the most advanced of their type By being optimised for group delay, as well as channel isolation, passband and channel spacing, they will enable global network equipment vendors to increase the number of channels (wavelengths) carried by a single fibre-optic cable while at the same time expanding per-channel bandwidth
This article was originally published on Electronicstalk on 13 Feb 2001 at 8.00am (UK)
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Fibre-optic network operators will reap the benefits of increased capacity and lower costs.
FBGs are optical filters built into the core of the fibre cable itself and are vital for the process known as dense wave division multiplexing (DWDM) whereby many wavelengths of light are used to carry data down a single-fibre cable.
DWDM is an essential and cost-effective method of handling the increasing amounts of data currently being transported by global network operators.
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However, as data traffic continues to grow, the operators need to increase the efficiency of DWDM systems and there are two main ways in which this can be achieved; firstly the number of wavelengths carried down a single fibre can be increased, and secondly each wavelength can be made to transport more data.
SPI's new BragNet family enables systems vendors to achieve both of these aims.
The BragNet family currently consists of the BragNet 100, 50 and 25 devices which offer channel spacings of 100, 50 and 25GHz, respectively.
In particular, the BragNet 25 is the most precise FBG currently available and will theoretically allow up to 160 wavelengths to be transmitted down a single fibre in the C-band (1529 to 1562nm).
In addition, the BragNet devices have a group delay of only +/-3ps - significantly lower than competing devices.
Group delay becomes an important parameter as individual wavelength data rates are increased to 10Gbit/s and onwards to 40Gbit/s; limiting group delay and its variation has the effect of limiting the introduction of dispersion which means that individual data pulses are less distorted over distance.
This enables higher per-channel bandwidth than with traditional FBGs and competing technologies such as AWGs (arrayed waveguide gratings) and thin-film filters.
The overall effect of incorporating BragNet filters in a DWDM system is more wavelengths per fibre and more bandwidth per wavelength, meaning greatly increased data transmission capability and lower costs for operators.
Traditionally, FBGs are made by writing a pattern onto a fibre using a UV laser and a custom 'phase mask'.
This hand-crafted approach is time consuming and inefficient, and the quality of the mask limits the accuracy of the final product.
Generally, they cannot achieve the necessary performance required for today's high channel-count DWDM systems.
BragNet filters are manufactured using Southampton Photonics' patented process, which automates the time-intensive design and production cycle with a computer controlled design-through-fabrication process.
This SPI-developed process is composed of two stages: design and fabrication.
The design stage of the process provides the company with a dramatic improvement in design capability compared with traditional competing methods, allowing the company to design very complex gratings optimised for specific network needs.
In the fabrication stage, SPI writes the pattern onto a fibre using a UV laser and a standard "phase mask," which provides it with much greater writing precision than the commonly used "hand-crafted" approach.
While competing systems are generally incapable of generating the performance required for today's high-channel count, high bandwidth systems, the SPI process enables greater complexity and control and is able to optimise any number of specifications.
This enables the company to manufacture the industry's most advanced gratings.
As a result Southampton Photonics has removed around 75% of the manual labour involved and can design and manufacture gratings from product definition to customer testable prototype in a matter of days, rather than the 6-8 weeks typical with traditional fibre grating design and fabrication methods.
Don Spalinger, president and cofounder of Southampton Photonics commented, "In less than the 12 months since making our initial funding announcement we've developed the world's most advanced family of fibre Bragg gratings.
Beta samples are already with high profile equipment vendors and the feedback has been excellent.
This is no mean feat, and the FBGs will prove an invaluable benefit to our customers and a key differentiator for our company.
It also adds credibility to the other products in our portfolio which includes laser arrays and amplifiers".
Southampton's family of BragNet FBGs are housed in athermal cylindrical metal packages with a diameter of 6.1mm and can operate over the -5C to +70C temperature range.
The 25GHz product is 110mm in length while the 50 and 100GHz devices measure 81mm.
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