Continuous wavelength tunable laser source with optimum orientation of grating and gain medium

An external cavity laser assembly for generating a light beam, the laser assembly comprising:

• a gain medium having a growth direction, a fast axis, a first facet, and a second facet that is spaced apart from the first facet, the gain medium generating the light beam when power is directed to the gain medium, the gain medium emitting from both facets, wherein a beam polarization of the light beam emitting from the second facet is perpendicular to the growth direction and the fast axis;
• a diffraction grating positioned in the path of the laser beam that emits from the second facet, the grating including a plurality of grating ridges that are substantially parallel to the beam polarization, wherein each of the grating ridges has a substantially rectangular shaped cross-sectional profile;
• and
• a grating mover that moves the diffraction grating relative to the gain medium about a grating pivot axis to tune the lasing frequency of the external cavity, wherein the grating pivot axis is approximately parallel to the beam polarization.