The AE 7100 series was designed as a laboratory high performance computer controlled fiber optic physical layer simulator for use in long haul, Enterprise and Metro optical network access testing applications. The AE 7100 is used in the design, analysis, conformance & performance testing of DWDM optical components, systems and specialized optical test equipment.

Typical DWDM Applications

Provides Three Modes Of Operation:

>Fiber distance (km)

>Physical mode attenuation (dB)

>Adjustment of chromatic dispersion (ps/nm)

The AE 7100 simulates Single Mode Fiber (SMF-28) for use in the C band and L bands in a single propagation direction. AE 7100 units, which utilize state of the art, fiber Bragg grating optical components, may be cascaded for longer lengths. The system is expandable for testing optical systems requiring multi-channel in ITU grid (200GHz spacing) or private wavelengths.

Configuration

The AE 7100 allows switchable lengths of 0, 15 km to 45 km in computer-controlled steps of 0.3km. The AE 7100 provides precise control over optical attenuation and chromatic dispersion. The unit is packaged in a 1U rack mountable chassis with front mounted optical connectors. System contains its own internal computer for controlling the simulated fiber’s optical characteristics. Several AE 7100 units can be connected together to form longer lengths, or in parallel for multiple channel testing. The AE 7100 is suitable for use in the 1530-1620 nm bands, and factory configured for specific wavelengths.(e.g. C Band-1550 nm) The AE 7100 can support over 20 GB/sec of data traffic, which is suitable for both OC-192(10 GB/sec) and OC-48 (2.5 GB/sec) optical system development.

AE 7100 System Features

Application & Benefits DWDM Systems

Dense Wavelength Division Multiplexing is the latest development of classic WDM (Wavelength Division Multiplexing) systems to allow increased capacity usage of single mode fiber. DWDM systems use a very densely packed spectrum of wavelengths, rather than just 1300nm and 1550 nm for WDM systems. The transmission of 32 channels from 1531.90 nm to 1558.98 nm is possible. This requires the development of wavelength multiplexes, with outputs tuned to specific ITU-T channel wavelengths. Each wavelength requires chromatic dispersion and attenuation compensation for a particular fiber type.

High bit rate optical networks like 10 Gb/sec and the emerging 40 Gb/sec require that optical components and systems are able to accommodate the effects of fiber type (eg. attenuation and chromatic dispersion) and physical impairments (e.g. splices and connectors). As the data rate increases above 1 GB/Sec. the effects of attenuation, chromatic dispersion (DWDM channels), degrade Bit Error Rate as optical pulses merge.

The AE 7100 is particularly suited for testing optical system performance which are impacted by attenuation (wide band) and chromatic dispersion, significant issues for 2.5 Gb/sec and 10 Gb/sec systems.

The AE 7100 provides flexible configurations where precise control of distance, attenuation and chromatic dispersion are required. This is especially true for automated testing , where it is often impractical to switch between different lengths and types of fiber. Variability between fibers, due to changes in ambient conditions, fibre kinks, splices and manufacturing tolerances cause different results compared to a precise laboratory test instrument such as the AE 7100.

A basic test system, as per Figure 1, shows the generic test scenario using BER as the primary measurement criteria for performance. Other approaches using purely optical test equipment connected to the AE 7100 are possible. The generic BER based testing configuration below can be used to test either optical components or optical systems to determine the effect of increasing fiber lengths with a resolution of 0.3 km. The AE 7100 is used to independently change attenuation with a resolution of 0.05 dB and/or chromatic dispersion effects on DWDM systems with a resolution of 6 ps/nm. Additionally, the AE 7100 can be used to simulate the effect of optical connectors and splices by introducing unusual attenuations and chromatic dispersions for system stress testing. Selecting the parameters defined by the specific fiber, the user, via the GUI, may introduce different combinations of “fault” conditions to determine how the device or system under test responds. For automated testing the Spirent AX 4000 traffic generator / BER analyzer and Spirent AE 7100 Optical Network simulator can be remotely controlled using RS-232, IEEE 488 and Ethernet for the AX 4000.

Other testing applications include Link Aggregation scenarios as outlined in Figure 2. By introducing different scenarios into each physical path (e.g. variable length and impairments) of the links using AE 7100’s, the impact on system switch-over and recovery performance as well as dealing with reduced data rates can be easily determined.

The AE 7100 Optical Network simulator provides the user the unique ability to simulate accurately fiber length, attenuation and chromatic dispersion for DWDM systems. The typical graphical representation of these parameters and how they interact is shown in the following diagrams for a single AE 7100 system. Multiple AE 7100 units can be cascaded in series or in parallel.

Figure 3.
Chromatic dispersion variation vs Fiber length which shows an AE 7100 with simulated SMF-28 fiber and also as a reference for another fiber type known as LEAF. Different fiber characteristics can be programmed into the AE 7100 initially at the factory.

Figure 4.
Diagram shows Chromatic dispersion as a function of Wavelength or Band. As can be seen at 1310 nm the affect on SMF-28 fiber is minimal in this example, however at 1550 nm the effect on the fiber performance deteriorates rapidly with distance.

Figure 5.
This diagram shows the variation of attenuation at a given wavelength.

Figure 6.
This diagram shows the working range of the AE 7100, comparing chromatic dispersion vs. attenuation which can be controlled independently by the user.