Multiband filters, which combine two or more separate bandpass filters into a single filter component, have advantages in many applications. Iridian has two decades of experience designing and manufacturing custom high performance dual band and multiband filters for a range of applications, including Telecom, Satcom and Spectroscopy.
Why use multi-band pass filters for DWDM?
Traditionally, single band pass filters have been used in telecommunication modules to perform wavelength/channel add-drop functionality and are commonly used components in WDM systems and PON modules. Iridian has previously developed CWDM and wide band multi-band pass filters to reduce accumulated insertion loss in these module/systems by “grouping” of ITU channels/wavelengths. With this method, module and system designers can improve the performance of these optical modules by using fewer components, resulting in a reduction in insertion loss and a more compact module size.
Taking advantage of years of experience and expertise in design and manufacture of multi-band filters, Iridian has expanded our capabilities to include narrow band, DWDM dual band pass filters (“DWDM-DB”). The pass bands widths possible with this new approach enable us to combine such functions as ITU 100GHz DWDM 2skip0 bands and 100G DWDM + CWDM dual band combinations.
Additonal Resources: Improving DWDM Module Performance with Narrow Dual Band Pass Filters
Multi band filters bands for PoN applications
Our multi-band filters have demonstrated many advantages in GPON, XG-PON, XGS-PON module applications. The new generation of muti-band filter designs have been applied in latest generation of PON modules. They have narrower pass band and reflect band width, steeper in transition bands, compared to traditional CWDM multi band filters. 
CWDM Dual Band filters are used to transmit one or more standard CWDM channels in two separate bands, and can have custom band widths designed for each band.
Iridian’s dual band filters are very popular in recent CWDM designs as they can reduce the number of filters required (and the associated packaging and alignment), minimize insertion loss and allow more compact module packaging.
Multi Band filters for Spectroscopy Applications
Iridian offers multiple bandpass spectroscopic filters for the UV-Visible-IR spectral regions. These filters typically have bandpass transmittance > 90% and blocking to OD > 6. The filters can have 2, 3 or even 4 band regions to allow use of multiple excitation sources or emission bands as required by the customer application.
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