Short-wavelength laser light source

A waveguide SHG light source of internal resonance type for inputting a fundamental wave component of semiconductor laser light to an optical waveguide including, in an optical substrate having spontaneous polarization, a polarization inversion portion having a periodically inverted direction of spontaneous polarization and for converting said fundamental wave component to a second harmonic, said SHG light source comprising:

• a diffraction grating disposed in the optical waveguide of the second harmonic output side of said polarization inversion portion to reflect said fundamental wave component of the semiconductor laser light toward said semiconductor laser;
• a pair of electrodes disposed on said diffraction grating to adjust a refractive index of said optical waveguide by applying a direct current voltage through an optical transparent thin film;
• means disposed in an end face of said optical substrate for inputting said semiconductor laser light or between said optical substrate and said semiconductor laser to transmit only the fundamental wave of said semiconductor laser light and reflect the second harmonic of said semiconductor laser light;
• and
• means for reflecting the fundamental wave of said semiconductor laser light, said reflecting means being disposed in an end face of said optical substrate opposite to said end face for inputting said semiconductor laser light.

A second harmonic generation device of waveguide type comprising:

• an optical substrate;
• and
• a ferroelectric optical waveguide layer having periodically arranged polarization inversion areas, periodic inversion boundary lines of polarization in the optical waveguide layer making an angle of 75.degree.-105.degree. with a surface or interface of said optical waveguide layer;
• wherein said substrate comprises lithium niobate (LiNbO.sub.3) doped with magnesium oxide, and the optical waveguide layer comprises lithium niobate or lithium niobate doped with a smaller amount of magnesium oxide as compared with the substrate.

A method for manufacturing a second harmonic generation device of waveguide type including a ferroelectric optical waveguide layer having periodically arranged polarization inversion areas, said method comprising at least the steps of:

• forming polarization inversion portions periodically on a substrate;
• and
• forming an optical waveguide layer on said substrate by using liquid epitaxial growth;
• wherein said liquid epitaxial growth has a film growth temperature of 800.degree. C. or below.

A second harmonic generation device of waveguide type comprising:

• an optical substrate;
• and
• a ferroelectric optical waveguide layer having periodically arranged polarization inversion areas, periodic inversion boundary lines of polarization in the optical waveguide layer making an angle of 75.degree.-105.degree. with a surface or interface of said optical waveguide layer;
• wherein said substrate comprises lithium tantalum niobate (LiTa.sub.x Nb.sub.1-x O.sub.3 ;0.ltoreq.x.ltoreq.1), and said optical waveguide layer comprises lithium niobate or lithium tantalum niobate having a higher niobium content as compared with said substrate.

A second harmonic generation device of waveguide type comprising:

• an optical substrate;
• and
• a ferroelectric optical waveguide layer having periodically arranged polarization inversion areas, periodic inversion boundary lines of polarization in the optical waveguide layer making an angle of 75.degree.-105.degree. with a surface or interface of said optical waveguide layer;
• wherein said substrate comprises potassium titanate phosphate (KTiOPO.sub.4) or potassium titanate arsenic phosphate (KTioAs.sub.x P.sub.1-x O.sub.4 ;
• 0.ltoreq.x.ltoreq.1), and said optical waveguide layer comprises potassium titanate arsenate (KTiOAsO.sub.4) or potassium titanate arsenic phosphate having a higher arsenic content as compared with said substrate.

A second harmonic generation device of waveguide type comprising:

• an optical substrate;
• and
• a ferroelectric optical waveguide layer having periodically arranged polarization inversion areas, periodic inversion boundary lines of polarization in the optical waveguide layer making an angle of 75.degree.-105.degree. with a surface or interface of said optical waveguide layer;
• wherein said substrate comprises potassium titanate phosphate (KTiOPO.sub.4) or rubidium potassium titanate phosphate (Rb.sub.x K.sub.1-x TiOPO.sub.4 ;
• 0.ltoreq.x.ltoreq.1), and said optical waveguide layer comprises rubidium titanate phosphate (RbTiOPO.sub.4) or rubidium potassium titanate phosphate having a higher rubidium content as compared with said substrate.

A method for manufacturing a second harmonic generation device of waveguide type including a ferroelectric optical waveguide layer having periodically arranged polarization inversion areas, said method comprising at least the steps of:

• forming polarization inversion portions periodically on a substrate;
• and
• forming an optical waveguide layer on said substrate by using liquid epitaxial growth;
• wherein said liquid epitaxial growth has a film growth temperature of 750.degree. C. or below.