Ridge waveguide semiconductor laser diode

A ridge waveguide semiconductor laser diode comprising:

• a semiconductor substrate,
• a front facet and a back facet;
• at least one active layer disposed over said semiconductor substrate and disposed between said front and back facets, said at least one active layer having a surface, and
• at least one cladding layer disposed over said at least one active layer and disposed between said front and back facets and having a ridge structure part and an underlying remaining part, said remaining part overlying said at least one active layer and having a thickness D, and
• wherein the laser diode emits a beam of light from its front facet when operated, the beam having a maximum power level substantially at its center and a peripheral edge where the power level of the beam is a fraction {fraction (1/e2)} of the maximum power level, wherein “e” is the base of the natural logarithm, the peripheral edge of the beam having a vertical width W as measured at the front facet and in a direction which is perpendicular to the surface of the at least one active layer, and
• wherein said thickness D has a value in the range of:
• 1.1×W>D≧0.5×W.

A ridge waveguide semiconductor laser diode comprising:

• a semiconductor substrate;
• a front facet and a back facet;
• at least one active layer disposed over said semiconductor substrate and disposed between said front and back facets, said at least one active layer having a surface;
• and
• at least one cladding layer disposed over said at least one active layer and disposed between said front and back facets and having a ridge structure part disposed over an underlying remaining part, said remaining part overlying said at least one active layer and having a thickness D;
• and
• wherein the laser diode emits a beam of light of wavelength λ from its front facet when operated, the beam generating a far-field pattern which comprises an oval shape, the far-field pattern having a maximum power level substantially at the center of the oval shape and a peripheral edge around the center where the power level of the far-field pattern is one-half of the maximum power level, the peripheral edge having a vertical width in a direction which is perpendicular to the surface of said at least one active layer, the vertical width having two distal ends, the beam further having a fall angle θv defined between the front facet and the two distal ends of the vertical width;
• and
• wherein said thickness D has a value in the range of:
• 1.1×W>D≧0.5×W, where W is related to θv by a relationship equivalent to:
• W = λ π · tan ⁡ ( θ V 2 · ln ⁢ ⁢ 2 ) ,
• where θv is provided in the dimensions of radians, where “1n 2” is the natural logarithm of 2, and where “tan” is the tangent function.