Broadband single mode SiGe graded waveguides with tight mode confinement for mid-infrared photonics

Graded Si 1−x Ge x waveguides with tight mode confinement in a broadband range of mid-infrared wavelengths are presented. Optimum TM mode confinement is observed due to the vertical variation of the refractive index. These waveguides show good potential for implementation as passive elements in mid-infrared optical circuits where strong mode confinement is required for a broadband range of wavelengths.