Cascaded broadband emission

A method of fabrication comprising:

• forming a first contact layer;
• forming a plurality of emission regions disposed one above another and separated by a plurality of corresponding tunnel junctions, and wherein each of the plurality of emission regions are configured with different respective band gaps to emit radiation of different wavelengths;
• and
• forming a second contact layer above the plurality of emission regions.

A method for operation a device, comprising:

• receiving a current at a first contact layer;
• providing the current to a plurality of emission regions disposed one above another and separated by a plurality of corresponding tunnel junctions, and wherein each of the plurality of emission regions are configured with different respective band gaps;
• and
• emitting electromagnetic radiation having a spectrum range from the plurality of emission regions, wherein each of the plurality of emission regions emits a respective portion of the spectrum range based on the respective band gap of the emission region.