ACHIEVING EFFICIENT SHG IN THIN FILM WAVEGUIDES BY ADJUSTING WAVEGUIDE PROPERTIES REFRACTIVE INDEX
Original Publication Date: 1979-Jun-30
Included in the Prior Art Database: 2004-Apr-01
Xerox Disclosure Journal
By second harmonic generation (SHG), frequency doubling can be obtained from infrared diode laser sources to create visible photons, such as 4500A (blue) photons. In such devices, the laser, such as DFB laser, is optically coupled to a thin film waveguide in which the frequency doubling takes place. By accurately controlling the refractive index of the waveguide to a predetermined value ne the efficiency of frequency doubling can be monitored and controlled. Control is achieved by electrical modulation of the laser waveguide refractive index. The diode laser 10 is provided at one end with a Bragg reflector grating 12 for feedback. The grating is fabricated to be in contact with or in proximity to the laser waveguide 14. The doubling waveguide 16 is fabricated to be optically coupled to the laser waveguide 14. Frequency doubling occurs in waveguide 16. A Schottky barrier 18 is evaporated on the top of and for the full width of the grating 12. The barrier may be an ohmic contact depending on the conductivity type of waveguide.