Broadband restricted MMI-based polarization beam splitter

A compact polarization beam splitter for a broad wavelength window comprising:

• a first birefringence waveguide device configured to receive a light signal at a first input port and split the light signal to a first TE polarization mode signal at a first bar output port and a first TM polarization mode signal at a first cross output port;
• a second birefringence waveguide device having a second input port coupled to the first bar output port and at least a second bar output port for further passing a second TE polarization mode signal;
• a third birefringence waveguide device having a third input port coupled to the first cross output port and at least a second cross output port for further passing a second TM polarization signal;
• wherein each of the second birefringence waveguide device and the third birefringence waveguide device is configured to be substantially the same as the first birefringence waveguide device comprising:
• a waveguide body in rectangular shape configured to yield no more than four modes;
• an input waveguide being coupled to a first end of the waveguide body at a location having a first distance away from a middle line along the length;
• a pair of output waveguides being coupled to a second end of the waveguide body at two mirrored locations having a second distance away from the middle line;
• wherein the first distance is substantially the same as the second distance equal to ⅙ of the width, so as to provide a polarization beam splitting mechanism for splitting a light signal in a broad wavelength window received at the input waveguide to a primarily TE polarization mode signal at one of the pair of output waveguide located at same side of the middle line and a primarily TM polarization mode signal at another one of the pair of output waveguide.