Optical Interleavers Information
Optical interleavers combine two sets of dense wavelength division multiplexing (DWDM) channels to form a composite signal. These passive fiber optic devices consist of 3 ports. The interleaving process is reproduced for creating denser composite signals featuring 50 GHz, 25 GHz, or 12.5 GHz spacing. These units are reversible to form optical deinterleavers separating denser DWDM signals into odd and even channels.
The technology is involved as an add-on module for upgrading existing setups and in the construction of advanced multiplexers and wavelength routers with an extended channel count. It is a cost-effective solution for maximizing bandwidth allocation in optical communication links.
Numerous types of optical interleavers exist today, including:
Standard or symmetric optical: These systems feature odd and even channels maintaining identical passband widths and waveforms.
Asymmetric optical: Odd and even channels possess distinct passband widths and waveforms in asymmetric components. This allows for superior passband and dispersion performance suitable for 40-Gb/s data rates. Select devices enable users to specify the passband widths ratios for odd and even channels.
Asymmetric optical units assist telecommunication carriers in migrating from low to high data rates. They enable a broad range of data rate signals to coexist on the existing infrastructure while engaging the same equipment.
Switchable optical: Switchable optical interleavers allow operation in two modes:
- Mode A (all pass): The setup supports any given channel spacing in the system. All channels pass through the component with an output from either one of the two ports.
- Mode B (interleaver mode): When switched from Mode A to Mode B, the device works as a standard instrument such as the 50-100GHz module. It operates as a conventional symmetric component or serves as an asymmetric unit with channel spacing occupying any frequency pair from N-GHz to 2N-GHz.
Co-packaged interleaver: Devices of this category consist of two structures occupying the same package. The elements feature three input and output ports. The paired mechanism is capable of functioning as an interleaver and deinterleaver or pairs of either item. Alternative configurations are subject to specification by users depending on the objective and preferred design.
Optical interleavers combine two sets of DWDM channels into an interleaving composite stream. For instance, two multiplexed signals with 200 GHz spacing after interleaving would amount to two denser DWDM signals with 100 GHz channel spacing. For enhanced density, performing the process again produces composite signals 50 GHz and then 25 GHz apart.
When employed in a reverse direction, an optical deinterleaver separates denser DWDM signals into odd and even channels. In most cases, DWDM equipment covers channel spacing of 100 GHz. A DWDCM signal with 50 GHz channel spacing is generated by taking two 100 GHz multiplexed signals and interleaving them. Replication of the activity results in denser composite signals of 25 GHz or 12.5 GHz spacing.
The signals occurring at the receiving end are subject to recovery through identical elements serving as splitters or optical deinterleavers. This helps an optical interleaving instrument to extend channel numbers for each fiber to a significant degree. They facilitate network or device upgrades without the requirement to modify every piece of equipment in the setup. It also permits increases in network bandwidth.
The mechanisms rely on multiple-beam interference. They are built using three primary methods:
Step-phase Michelson interferometers are systems based on the combination of Michelson interferometers with Gires-Tournois interferometers.
Mach-Zehnder interferometer (MZI) connects the input directional coupler, output coupler, and a differential delay section. It is deployed as a building block for complex interleaver systems.
Birefringent crystal networks are integrated into the interleaving components involved in bulk optics. They engage lattice structures in supporting flat-top structures. Such products offer a simple configuration and reliability.
Applications and Features
The principal applications of optical interleavers are in multiplexing, wavelength routing, and prefiltering. Individual devices may include a number of unique characteristics, including:
- C-band wavelength coverage
- L-band wavelength coverage
- C+L-bands wavelength coverage
- Channel spacing 12.5-25 GHz
- Channel spacing 25-50
- Channel spacing 50-100
- Channel spacing 100-200
- Custom channel spacing
- Dual-stage function
- Step-phase interferometer
- Wide passband
- Low dispersion
- Low insertion loss
- Low PDL
- High channel isolation
- Low thermal drift
- Fiber length
- Optical connector type