Jds Uniphase Corporation

Koninklijke Philips Corporation N.V.

Leo M Weegels

Henricus M De Vrieze

Bernardus A Van Bakel

Johanna M Bokhorst

Johannes Cornelis Van De Ven

Hendrik G Pomp

Maria H Vermeulen-Hartjes

The invention relates to a display device comprising LC panels arranged next to each other. To reduce the visibility of a seam between two adjacent LC panels and to avoid grey scale inversion, collimated light is applied. A lenticular foil is used to enlarge the viewing angle in the horizontal direction. If the seam is only present in a vertical direction, the widest viewing angle in the vertical direction should be chosen. This choice leads to an asymmetric viewing angle in a horizontal direction. To reduce the asymmetry in the horizontal viewing angle, the lenticulars of the screen have a trapezoidal shape. The apex angle depends on the desired spread and viewing angle symmetry in the horizontal direction.

Display device and lenticular screen

An optoelectronic device, such as a laser of the ridge waveguide type, can be provided with the necessary mesa (14) by means of wet or dry etching with a mask (20). The etching process is stopped when an etching stopper layer (5) is reached. A laser obtained by wet etching is indeed least expensive, but it is found to have a kink in its power-current characteristic at an undesirably low power value. According to the invention, such a laser must be manufactured in that the mask (20) used is given a width which is (much) greater than the width desired for the mesa (14), and in that, after a (preferably wet) etching process down to or down to close to the etching stopper layer (5), etching is continued with a wet isotropic etchant which is selective relative to the etching stopper layer (5) until the mesa (14) formed has the desired width. A very narrow and steep mesa (14) can thus be realized in an inexpensive manner. It is found that a laser with such a mesa (14) does not exhibit the kink mentioned above until at a comparatively high power. When used in the GaAs/AlGaAs material system, the invention results in a laser which is highly suitable for use as a writing laser in a system for optical registration, or as a pumping laser in a system for glass fiber communication. The two etching steps mentioned may be carried out with one and the same wet etchant, for example an etchant based on C.sub.6 H.sub.8 O.sub.7 (citric acid) in the case of the GaAs/AlGaAs material system. It is alternatively possible, for example, to use two etchants, for example the etchant based on citric acid mentioned above and a second etchant based on Na.sub.2 Cr.sub.2 O.sub.7.

Method of manufacturing an optoelectronic semiconductor device

A diode laser is disclosed that is self-pulsating without an increase in the starting current or a decrease in the efficiency. A special coating on an end face of the laser comprises in order a first mirror, a medium having an optical thickness which is at least substantially equal to an integer number of times half the wavelength of the generated electromagnetic radiation, and a second mirror. The coating comprises exclusively materials which have a higher bandgap value than that which corresponds to the wavelength of the generated radiation, while the reflectivities of the mirrors and the deviation of the optical thickness of the medium with respect to an integer number of times half the emission wavelength are chosen such that the group velocity dispersion (GVD) adjacent the wavelength of the generated electromagnetic radiation is negative, and preferably a minimum. Pulse widening owing to pulses arising from automatic mode locking is no longer possible due to a sufficiently negative group velocity dispersion. A laser exhibiting stable self-pulsation is thus provided.

Semiconductor diode laser, and method of manufacturing thereof

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Eindhoven, Netherlands

Leo M Weegels