The Application of WDM Channel Skip Filters

Application Notes, Learning Center

Channel skip filters are components added to wavelength division multiplexing (WDM) add/drop modules — in both coarse wavelength division multiplexing (CWDM) and dense wavelength division multiplexing (DWDM) applications — to facilitate band splitting and to manage multiple ITU channels.

These filters feature narrow transitions from pass band to blocking band, minimizing lost channels while maintaining high spectral efficiency (i.e., limiting insertion loss) since the express channels undergo only one reflection.

Advantages of Multiple Band Pass Filters in Telecommunications Applications

Application Notes, Learning Center

In wavelength-division multiplexer (WDM) and passive optical network (PON) modular design, single band pass filters and multiple band pass filters are used for the same purpose: permitting narrow wavelength ranges to pass through while rejecting wavelengths outside that range (known as the filter’s upper and lower cutoff frequencies).

Multiple band pass filters are used to transmit two or more standard coarse wavelength division multiplexing (CWDM) channels, separating them from the other CWDM bands — replacing two or more single band pass filters with a single component.

Hybrid Gain Flattening Filters in Optical Fiber Amplifiers

Application Notes, Learning Center

Much like vehicle hand cranks in their day, the use of a gain flattening filter (GFF) paired with a wavelength- division multiplexer (WDM) in optical fiber amplifiers – such as erbium-doped fiber amplifiers (EDFA) — has been accepted not because it is ideal, but because a superior solution had yet to be created. Until now.

This article explains what a Hybrid GFF is and how it works. It also details the advantages of using Iridian Spectral Technologies’ Hybrid GFFs in lieu of a conventional two-filter setup in EDFA and other optical filter applications.

How to Clean Optical Filters

How To, Learning Center

How to Clean Optical Filters?While the Iridian filters are hard coated filters, the filters are delicate and should be handled with care to avoid or minimize direct contact with any other optics. All Iridian filters may be cleaned using the following recommended method. 

How to Specify Surface Figure and Wavefront Distortion for Multi-layer Optical Filters

How To, Learning Center

Optical filters are used in many applications and the surface figure and wavefront distortion requirements of filters are dependent on where and how they are used. Whereas band-pass or clean-up functionality may only require control of the transmitted wavefront, dichroic beam-steering/splitting filters or wavelength selective mirrors likely require specification of both the transmitted and reflected beams. If filters are only used in sensing applications with very tolerant detector geometries, there may be no need, in practice, to put any constraints on the surface figure or wavefront distortion. It is important to understand where, when, how, and how much to specify wavefront distortion to ensure that functional requirements are guaranteed while unnecessary and costly constraints are avoided.