Abstract: A radiation-emitting semiconductor diode, especially a laser having a first and a second cladding layer, an active layer and a mesa which comprises at least the second cladding layer and which lies recessed in a third cladding layer. The second cladding layer comprises a first sub-layer which adjoins the active layer and is comparatively thin, and a second sub-layer which adjoins the first sub-layer and is comparatively thick, while the refractive index of the first sub-layer is lower than that of the second sub-layer. Confinement in the thickness direction of charge carriers and radiation is good in such a diode, while the third cladding layer has a relatively high refractive index (giving a relatively low bandgap). Thus, the third cladding layer has a relatively low aluminium content, while providing good lateral confinement.

Abstract: An array of semiconductor diode lasers (11, 12) is a very suitable radiation source for various applications such as optical read and write systems and laser printers. Such an array includes a semiconductor body (10) with a substrate (1) and a layer structure provided thereon in which at least two lasers (11, 12) are formed which are mutually separated by a groove (20). In the known array, the groove (20) reaches down into the substrate (1), so that the lasers (11, 12) are electrically separated from one another. According to the invention, the array of lasers (11, 12) is provided with a groove (20) with a major portion (d) of its depth (D) which is situated within the substrate (1). As a result of this, the lasers (11, 12) of the array show a surprisingly low crosstalk. Preferably, the portion (d) of the groove (20) situated in the substrate (1) is at least 3 .mu.m deep. The best results are obtained with depths (d) of approximately 10 up to at most 40 .mu.m.

Abstract: Semiconductor diode lasers are used inter alia in optical disc systems, laser printers, bar code readers, and glass fibre communication systems. Lasers having a so-called (weakly) index-guided structure are very suitable for many applications inter alia because they can be manufactured comparatively simply and reliably. A disadvantage of the known (weakly) index-guided laser is that the so-called P-I (=optical power-current) characteristic thereof exhibits a kink. Such a kink limits the use of the laser to a relatively low optical power. According to the invention, such a (weakly) index-guided laser has a resonance cavity with a length for which the optical power at which a kink occurs in the P-I characteristic is a maximum. It was a surprise to find that the occurrence of a kink in the P-I curve of such a (weakly) index-guided laser depends on the length of the resonance cavity. Very surprising is the appearance of a maximum value in this kink power as a function of the length of the resonance cavity.

Abstract: Radiation-emitting semiconductor diodes are used as laser diodes or LEDs inter alia in optical disc systems, laser printers and bar code readers. The emission wavelength in these cases lies preferably in the visible range of the spectrum. Known diodes have an active layer (3A) and cladding layers (2, 4) which comprise either AlGaAs or InAlGaP. These known diodes have the disadvantage that they do not cover a portion of the visible spectrum between 880 and 600 nm.A diode according to the invention is characterized in that the active layer (3A) comprises Al.sub.x Ga.sub.l-x As and the cladding layers (2, 4) comprise Al.sub.y Ga.sub.w In.sub.l-y-w P, while the active layer (3A) has such an aluminjure content (x) and such a thickness (d) that the wavelength of the photoluminescence emission lies between approximately 770 and 690 nm.

Abstract: Radiation-emitting semiconductor diodes are used inter alia in information processing systems as diode lasers or LEDs. Such a radiation-emitting semiconductor diode including an active layer situated between two cladding layers, which layers each include a mixed crystal of III-V semiconductor materials, atoms of different elements, often having a certain degree of ordering, being present on at least one sublattice. An example is an InGaP/InAlGaP diode laser which emits at 670 nm and is highly suitable for various applications. There is a particular demand for diodes which have a high maximum operating temperature at a given wavelength. According to the invention, the composition of the semiconductor material of the active layer is so chosen that this layer has a compression strain, while the atoms of the different elements have a less orderly distribution at least in the semiconductor material of the active layer.

Abstract: Articles and process for wavelength conversion are disclosed which use a series of aligned sections of optical materials for wavelength conversion selected from materials having the formula K.sub.1-x Rb.sub.x TiOMO.sub.4 where x is from 0 to 1 and M is selected from P and As and materials of said formula wherein the cations of said formula have been partially replaced by at least one of Rb.sup.+, Tl.sup.+ and Cs.sup.+, and at least one of Ba.sup.++, Sr.sup.++ and Ca.sup.++. The series of sections is characterized with regard to a change in nonlinear optical coefficient, section length, and section .DELTA.k (i.e., the difference between the sum of the propagation constants for the incident waves and the sum of the propagation constants for the waves generated). The sections are selected such that the sum for the series of the product of the length of each section with the .DELTA.k is equal to about 2.pi.

Abstract: A semiconductor diode laser array, in which the active regions (3) are arranged in at least two groups, which are located in (two) substantially equidistant planes (V and W). At least one of the groups should comprise at least two active regions.According to the invention, the active regions (3) of one group located in the plane V are fully separated by at least one of the enclosure layers, for example the enclosure layers 2 and 4 (FIG. 1) or the enclosure layer 4 (FIG. 4) from the active regions 3 of the other group located in the plane W.

Abstract: An optical device includes a phase-locked diodelaser array (10), a collimator lens (17), and behind the collimator lens a prism system (30, 34) of at least one prism to broaden the far field radiation pattern in the lateral plane (XY) and a spatial filter (19) to select a favored mode. The laser radiation is concentrated into a single, round and diffraction limited spot (V).

Abstract: A polarization-rotator (22) and a polarization-sensitive beam combiner (30') are arranged in the radiation path between a phase-locked diode laser array (10) radiating in a stable supermode and a collimator lens (46). The two radiation lobes (11, 12) are superposed so that a single radiation spot (S) can be obtained. The quality of the spot can be improved by an arrangement of a prism system (40) and a spatial filter (45) in the lateral far field.

Abstract: According to the method a rotating recording element 23 (FIG. 3) having a crystalline recording layer 28 of the composition Q.sub.x Sb.sub.y Te.sub.z, wherein Q=In, Ga; X=34-44 at. %; y=51-62 at. %; Z=2-9 at. %; is exposed to a pulsated laser light spot 29 (FIG. ) in which amorphous information bits are formed which are read by means of weak laser light 30 and which can be erased in real time during one revolution of the element 23 by means of a laser light erasing spot 33 (FIG. 4) and be returned to the crystalline state.

Abstract: A method is provided for the optical recording of information in which an amorphous recording layer 4 having a composition according to formula (1) provided on a synthetic resin substrate (2) (FIG. 1) in a maximum layer thickness of 150 nm is exposed of infrared laser light having a wavelength of 750-900 nm and pulsed in accordance with the binary information to be recorded with a pulse time of at most 200 ns. A crystalline area 6 (bit) having maximum dimensions of a few micrometers is formed in the amorphous layer in the exposed places. As optical recording element is also provided for use in the method.

Abstract: A method for the optical recording of information in which a recording layer 4 of In.sub.x Sb.sub.1-x, Ga.sub.x Sb.sub.1-x or (InSb).sub.y Se.sub.1-y, wherein 0.4.ltoreq.x.ltoreq.0.6 and 0.7.ltoreq.1.0, or mixtures thereof, provided on a synthetic resin substrate (2) (FIG. 1) in a maximum layer thickness of 150 nm is exposed to infrared laser light having a wavelength of 750-900 nm which is pulsated in accordance with the binary information to be recorded with a pulse time of at most 200 ns, a crystalline area 6 (bit) having maximum dimensions of a few micrometers being formed in the amorphous layer in the exposed places, as well as an optical recording element used in the method.