Semiconductor laser

A semiconductor laser comprising:

• a first transparent dielectric film formed on at least either a front or rear facet through which oscillating light passes, said first transparent dielectric film consisting of aluminum oxide (Al2O3);
• a second transparent dielectric film formed on said first transparent dielectric film, said second transparent dielectric film consisting of titanium dioxide (TiO2);
• and
• a third transparent dielectric film formed on said second transparent dielectric film, said third transparent dielectric film consisting of silicon dioxide (SiO2);
• wherein the following relationships are satisfied:
• 0.09λ≦n1d1≦0.15λ
• 0.20λ≦n2d2≦0.22λ
• 0.225λ≦n3d3≦0.245λ
• where λ is the oscillating wavelength, n1, n2, and n3 are the refractive indices of said first, second, and third dielectric films with respect to said oscillating wavelength, and d1, d2, and d3 are the thicknesses of said first, second, and third dielectric films.

A semiconductor laser comprising:

• a first transparent dielectric film formed on at least either a front or rear facet through which oscillating light passes, said first transparent dielectric film consisting of aluminum oxide (Al2O3);
• a second transparent dielectric film formed on said first transparent dielectric film, said second transparent dielectric film consisting of tantalum pentoxide (Ta2O5);
• and
• a third transparent dielectric film formed on said second transparent dielectric film, said third transparent dielectric film consisting of silicon dioxide (SiO2);
• wherein the following relationships are satisfied:
• 0.09λ≦n1d1≦0.15λ
• 0.20λ≦n2d2≦0.22λ
• 0.225λ≦n3d3≦0.245λ
• where λ is the oscillating wavelength, n1, n2, and n3 are the refractive indices of said first, second, and third dielectric films with respect to said oscillating wavelength, and d1, d2, and d3 are the thicknesses of said first, second, and third dielectric films.