Narrow beam divergence laser diode

A multilayer laser diode comprising:

• an optical waveguide region having a quantum well layer and at least one high refractive index layer on each side of the quantum well layer,
• upper and lower cladding regions respectively on each side of the optical waveguide region, each such region having a first low refractive index layer adjacent to the high refractive index layer and a second refractive index layer formed adjacent to a first low refractive index layer and having an even lower refractive index than such first low refractive index layer;
• a lower buffer layer adjacent to the lower cladding region;
• a cap layer for providing an electrode and positioned adjacent to the cladding region;
• and
• the energy of the lasing light of the laser diode being selected tob e lower than the energy gap of the cap layer and lower buffer layer that are adjacent to the cladding regions.