Device and method for filtering optical wavelengths

An optical wavelength selective filter comprising:

• 3 dB-coupler or at least one Q-port circulator, where Q≧3;
• a 1×N WDM-(de)multiplexer, where N≧2;
• N number of waveguides, where one of the ports on the circulator or on the 3 dB-coupler is connected to a first side of the WDM-(de)multiplexer, wherein each waveguide includes
• at least one variable optical attenuator;
• and
• at least one reflection section, such that at least one variable optical attenuator is disposed between a reflection section and the WDM-(de)multiplexer;
• wherein the variable optical attenuators are of the MMIMZI-type (Multi Mode Interference Mach Zehnder Interferometer) comprising two MMI-waveguides which are mutually connected via two Mach Zehnder waveguides, wherein a first Mach Zehnder waveguide includes at least one trim section, and wherein a second Mach Zehnder waveguide includes at least one phase control element.

A method of selectively filtering at least one wavelength from a group of wavelengths, comprising:

• transmitting optical wavelength channels to a first side of a WDM-(de)multiplexer via an optical circulator or a 3 dB-coupler;
• transmitting N number of different wavelength channels through N number of different waveguides connected to a second side of the WDM-(de)multiplexer, where N≧2;
• attenuating at least one but at most N−1 number of optical wavelength channels prior to said channel or channels being reflected by a wavelength selective reflection section;
• and
• transmitting the reflected optical wavelength channels through said WDM-(de)multiplexer and from there through said circulator or 3 dB-coupler.

An optical wavelength selective filter comprising:

• coupler or a circulator;
• a multiplexer/demultiplexer;
• and
• a plurality of waveguides, wherein each of the plurality of waveguides includes
• a reflection section;
• and
• a variable optical attenuator wherein the variable optical attenuator is disposed between the reflection section and the multiplexer/demultiplexer;
• wherein one of the ports on the circulator or on the coupler is connected to a first side of the multiplexer/demultiplexer.