Based on the SFP package based digital adjustable optical attenuator
Adjustable optical attenuator (VOA) is an important optical fiber in
optical fiber communication system, a dynamic device, mainly used for
the channel in dense wavelength division multiplexing (DWDM) system of
power balance, realize gain flat, dynamic gain balance and balance of
the transmission power.And because digital adjustable optical
attenuator control is simple, small volume, good optical performance
and get a bigger development.
Current adjustable optical attenuator has been widely used in the
field of optical communication in communication equipment, general
practice is integrated in the equipment digital adjustable optical
attenuator, through equipment software according to the needs of the
system the attenuation of the adjustable optical attenuator
adjustment, due to VOA integrated into devices, optical path must also
be integrated in the equipment, and fixed, which makes the light path
system is not flexible configuration, and in DWDM systems, different
sites, different transmission capacity is flexible according to the
actual network configuration, and VOA as important configurable device
in the system, not as the system configuration and flexible choice,
the flexibility of the system equipment, increased the system cost.
In the field of optical communications, SFP pluggable transceiver
module as a standard device, because of its small size, mechanical and
optical interface standard unified, flexible and configurable features
such as pluggable, has been widely applied in the system devices. To
make the VOA module could be like sfp transceiver module can be
configured as a flexible application of the device to the system, this
paper presents a VOA module will be integrated into the SFP package,
using standard mechanical and optical SFP interface, so VOA module
could be like fiber optic transceiver module and play, very easy to
achieve light attenuation choice.
As a result of SFP package volume has been greatly restricted, and
based on MEMS (Micro-Electro-Mechanical Systems, MEMS) relative to
other types of VOA prominent feature is the small size of VOA's
technology, simple control, and has good optical properties.
Therefore, this article uses MEMS VOA module SFP package digitally
adjustable attenuator.
1. digital MEMS VOACommon MEMS VOA are mirror rotation and
displacement shade, etc.Either type of light power attenuation, is
through the light attenuation and rotation or movement of the MEMS
chips machinery is one-to-one relationship, and in the chip of
mechanical rotating or moving again and add in the voltage on the top
and bottom plates were one-to-one correspondence relationship,
therefore, is one to one correspondence relation between attenuation
and voltage, but the attenuation is not linear relationship to the
driving voltage.In order to realize digital attenuation control, need
to increase the control circuit, advance the attenuation data stored
in the circuit, voltage curve through customer send attenuation
automatically search the corresponding attenuation voltage, then send
to VOA driving circuit, driving circuit and output the corresponding
voltage to VOA, so as to realize the corresponding attenuation, thus
achieve the goal of the digital control.
2. Based on the SFP package based digital adjustable optical
attenuator
SFP-based package represented by the variable optical attenuator
section, the optical module MEMS VOA, part of the LC optical port, an
electrical control unit CU, electrical interface, the structure and
composition shown in Figure.
In structural terms, the use of standard SFP package
3 adjustable optical attenuator based on SFP packaging
applicationsAdjustable optical attenuator based on SFP encapsulation
performance indicators and MEMS digital adjustable optical attenuator
indicators are similar, with fast response, good linearity and high
stability, high attenuation, such as optical performance, at the same
time, the adoption of SFP encapsulation, make the digital adjustable
attenuator became an independent optical module, support hot plug and
plug and play, do not need to be integrated into the equipment,
equipment for as long as you set aside SFP interfaces, can according
to the requirements of the system, the flexible configuration need
adjustable attenuator, make the light path system is flexible and
simple, at the same time, because of its flexible configuration, save
the cost of the system net change growth, reducing the overall cost
optical network equipment.
4 conclusionAdjustable optical attenuator based on SFP encapsulation
in optical devices tend to be pluggable optical device of the trend,
with the portable flexible characteristics of 10g sfp module, at the same
time with the traditional similar optical properties to the adjustable
optical attenuator, very suitable for WDM systems is applied to the
complicated equipment, flexible of all kinds of network applications,
therefore has wide application prospect.