Lasers with ingaas(p) quantum wells with indium ingap barrier layers with reduced decomposition

A method for preparing a vertical cavity surface emitting laser (VCSEL) comprising:

• using MBE for:
• growing a first mirror region over a GaAs substrate, the first mirror region having a plurality of first mirror layers having one or more indices of refraction;
• growing a first conduction region over the first mirror region;
• growing an active region over the first conduction region opposite of the first mirror region, the growth of the active region comprising:
• (a) growing a quantum well barrier having InGaP(As);
• (b) growing an transitional layer having one or more of GaP, GaAsP, or GaAs;
• (c) growing a quantum well layer having InGaAs(P);
• (d) growing another transitional layer having one or more of GaP, GaAsP, or GaAs;
• (e) repeating processes (a) through (d) over a plurality of cycles;
• and
• (f) growing a quantum well barrier having InGaP(As);
• growing a second conduction region over the active region opposite of the first conduction region;
• and
• growing a second mirror region over the second conduction region, the second mirror region having a plurality of second mirror layers having one or more indices of refraction.

A vertical cavity surface emitting laser (VCSEL) comprising:

• a quantum well barrier prepared from a first material;
• a quantum well prepared from a second material;
• and
• one or more transitional monolayers between the quantum well barrier and quantum well, the one or more transitional monolayers being formed from a third material selected such that group III interdiffusion and/or group V interdiffusion with the quantum well barrier and/or quantum well results in one or more transitional monolayers having a wider band gap compared to a low band gap interface that results from group III interdiffusion and/or group V interdiffusion between the quantum well barrier and quantum well without the one or more transitional monolayers.