U.S. Philips Corporation

Antonius H Venhuizen

Gerardus L Rikken

Dirk Jan Broer

Christianne Rm De Witz

Constance J Seppen

David B Braun

An illumination system has an active layer which includes an electroluminescent material, the active layer being located between an optically transparent electrode layer and a reflective electrode layer. A reflective polarizer is present at a side of the transparent electrode layer facing away from the active layer. A sub-beam incident on the polarizer and having an unwanted polarization is reflected back to the active layer, where it is again partially depolarized to recover a component having the desired state of polarization. The invention also relates to a flat-panel picture display device which includes such an illumination system.

Electroluminescent illumination system

An optical component (7) is described in which the frequency of electromagnetic radiation is raised and which comprises a non-linear optical medium and an optical modulation structure (21) so as to compensate for the wavelength dispersion in the non-linear optical material so that there is phase matching. By providing a satellite layer (15) having a high refractive index proximate to the modulation structure (21), the wavelength at which phase matching occurs is not critical for the layer thickness of the non-linear optical medium. An opto-electronic device (1) for raising the frequency of electromagnetic radiation, comprising such a component (7) as a frequency-raising element is also described.

Optical component and opto-electronic device for raising the frequency

Optoelectronic semiconductor device comprising a waveguide and method of manufacturing such a device. Optoelectronic semiconductor devices which have a groove-shaped waveguide in an oxide layer provided on a silicon substrate are compact, easy to manufacture, and--when the waveguide comprises a non-linear optical material--applicable inter alia for frequency doubling of laser radiation. In known devices, scattering losses occur in the waveguide owing to the roughness of the groove which arises during etching of the groove. Here the groove and a portion of the oxide layer are formed by local, preferably thermal, oxidation of the silicon substrate. The groove formed at the area of the oxidation mask has a smoother surface and as a result the waveguide has lower losses. When the device includes a GaAs/AlGaAs diode laser, it forms an efficient, compact, inexpensive and blue-emitting laser source which is suitable for use in an optical disc system. Preferably, the diode laser is situated in a deeper and wider further groove in the oxide layer. The devices may be made by a method in which, a layer of silicon oxide and a groove therein are formed simultaneously through the use of local oxidation. Grooves of different widths and depths are obtained by using masks of various widths.

Optoelectronic semiconductor device comprising a waveguide and method of

An optical component (7) is disclosed in which the frequency of electromagnetic radiation is increased and which comprises a non-linear optical waveguide (11 ) which is provided on a supporting material (9). The field distributions of the fundamental wave and the frequency-increased wave can be made to overlap by providing a satellite layer (15) having a high refractive index on at least one side of the non-linear optical waveguide (11), so that the efficiency of the frequency is high. The invention also relates to an optoelectronic element (1) for increasing the frequency of electromagnetic radiation, comprising a frequency-increasing element in the form of such a component (7).

Optical component and optoelectronic element for increasing the

Optoelectronic semiconductor devices which have a groove-shaped waveguide in an oxide layer provided on a silicon substrate are compact, easy to manufacture, and--when the waveguide comprises a non-linear optical material--applicable inter alia for frequency doubling of laser radiation. In known devices, scattering losses occur in the waveguide owing to the roughness of the groove which arises during etching of the groove. Here, the groove and a portion of the oxide layer are formed by local, preferably thermal, oxidation of the silicon substrate. The groove formed at the area of the oxidation mask has a smoother surface and as a result the waveguide has lower losses. When the device includes a GaAs/AlGaAs diode laser, it forms an efficient, compact, inexpensive and blue-emitting laser source which is suitable for use in an optical disc system. Preferably, the diode laser is situated in a deeper and wider further groove in the oxide layer. The devices may be made by a method in which, a layer of silicon oxide and a groove therein are formed simultaneously through the use of local oxidation. Grooves of different widths and depths are obtained by using masks of various widths.

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Eindhoven, Netherlands

Antonius H Venhuizen