# Multi Mode Interferrometers¶

A multimode interferometer is essentially a broad waveguide with many (but a finite number) of guided modes. Each mode i, which we indicate as ψi, has a propagation constant βi. Because the modes are eigenmodes, they propagate independently from one another. When an MMI is excited by an incident wave, the field profile is decomposed into the eigenmodes. Even though there is no exchange of energy between these eigenmodes, they propagate at a different velocity, and the result is an interference pattern that changes along the length fo the MMI.

In order to avoid reflections, tapers are usually added to couple the access waveguide to the part of the MMI where the interference takes place. In Picazzo we provide MMIs with and without those tapers.

## Tapered MMIs¶

 MMITapered Rectangular multimode interferometer, generated from a waveguide template with tapers. MMIIdenticalTapered Rectangular multimode interferometer, generated from a trace template with indentical input and output trace_templates and with tapers. MMISymmetricTapered MMI with symmetrically distributed access templates and with tapers. MMI1x2Tapered MMI with one access waveguide and two output waveguides and with tapers that symmetrically distributed. MMI2x1Tapered MMI with two access waveguides and one output waveguides and with tapers that symmetrically distributed. MMI2x2Tapered MMI with one access waveguide and two output waveguides and with tapers that symmetrically distributed.

## Untapered MMIs¶

 MMI Rectangular multimode interferometer, generated from a waveguide template MMIIdentical Rectangular multimode interferometer, generated from a trace template with indentical input and output trace_templates. MMISymmetric MMI with symmetrically distributed access templates. MMI1x2 MMI with one access waveguide and two output waveguides that symmetrically distributed. MMI2x1 MMI with two access waveguides and one output waveguides that symmetrically distributed. MMI2x2 MMI with one access waveguide and two output waveguides that symmetrically distributed.

## Rib MMIs¶

 RibMMIIdenticalTapered Rectangular multimode interferometer, using a Ribwaveguide for the MMI with identical input and output trace_templates and with tapers. RibMMISymmetricTapered Rib MMI with symmetrically distributed access templates and with tapers. RibMMI1x2Tapered Rib 1x2 MMI with symmetrically distributed access templates and with tapers. RibMMI2x1Tapered Rib 2x1 MMI with symmetrically distributed access templates and with tapers. RibMMI2x2Tapered Rib 2x2 MMI with symmetrically distributed access templates and with tapers.