Abstract: A process for melting silicon, in which silicon bodies (4; 14; 24) are detached from a silicon starting material (2) - (40) -, the silicon bodies (4; 14; 24) being dimensioned - (40) - in such a way that they can be arranged in a heatable crucible (6), the silicone bodies (4; 14; 24) are arranged in the crucible (6) and the crucible (6) is heated - (46) -, at least some of the cavities (10) that occur between the crucible walls (7) and the silicon bodies (4; 14; 24) or between monolithic parts of the silicon bodies (4; 14; 24) when the silicon bodies (4; 14; 24) are arranged in the crucible (6) - (42) - being at least partially filled with silicon granules (8; 18, 20; 28) - (44) -, and an arrangement for melting silicon.

Abstract: A process for melting silicon, in which silicon bodies (4; 14; 24) are detached from a silicon starting material (2) - (40) -, the silicon bodies (4; 14; 24) being dimensioned - (40) - in such a way that they can be arranged in a heatable crucible (6), the silicone bodies (4; 14; 24) are arranged in the crucible (6) and the crucible (6) is heated - (46) -, at least some of the cavities (10) that occur between the crucible walls (7) and the silicon bodies (4; 14; 24) or between monolithic parts of the silicon bodies (4; 14; 24) when the silicon bodies (4; 14; 24) are arranged in the crucible (6) - (42) - being at least partially filled with silicon granules (8; 18, 20; 28) - (44) -, and an arrangement for melting silicon.

Abstract: An exemplary method of production of solar grade silicon is disclosed. The method comprises melting the silicon and directionally solidifying the melt. The method additionally comprises forming a crystallization front during the directional solidification, the front having the shape of at least a section of a spherical surface. Also disclosed are a silicon wafer and a solar cell in accordance with an exemplary embodiment of the present invention.

Abstract: Optical time-division multiplexing of two or more digital optical input signals applied to an optical multiplex element to produce a single optical output signal is performed. In the multiplex element, the input signals are optically switched through in alternation, a through-switching time interval being shorter than the duration of a pulse of the input signal. An optical time-division multiplexer has at least one multiplex element to which at least two optical signal are input, the signals having carriers of different wavelengths. The signals are connected to an optical signal output via a junction. The signals can be switched through to the signal output in alternation by a switchable filter.

Abstract: A semiconductor laser which includes a controllable beam splitter has three segments including laser-active zones and a monitor diode forming a cross-shaped laser connected with one another by way of the beam splitter. The beam splitter is equipped with electrodes for controlling optical coupling between the segments.

Abstract: Optical components made of inorganic crystals, e.g. lithium niobate, have the drawback that they cannot be integrated on a semiconductor substrate. In addition to linear optical characteristics, polymer plastics also have strong, non-linear characteristics. According to the invention, these plastics are integrated on a semiconductor substrate and serve as polarizers, modulators, optical switches, etc. Additionally, they require less space than prior art crystals.

Abstract: An improved optical isolator (6) for a semiconductor laser (2) for use in optical communication systems consists of a polarizer (4) and a birefringent medium (5). An electric field is applied to the birefringent medium (5) via electrodes (7) for varying the indices of refraction of the birefringent medium (5). By the variation of the indices of refraction, the optical isolator (6)can be adapted to different light wavelengths.

Abstract: A switchable DFB (distributed feedback) laser which includes a waveguide layer having an impressed diffraction grating composed of two or more superposed subgratings having different respective grating constants. The diffraction grating is either frequency modulated (FIG. 3a) or amplitude modulated (FIG. 3b) or is a mixed form of these two types of modulation. Each subgrating can be employed to generate an emission wavelength that is a function of the grating period. By changing the temperature or changing the injection current, the effective index of refraction of the laser is changed, thus enabling the setting of an emission wavelength which is a function of the modulated diffraction grating. The switchable DFB laser according to the present invention may be employed for optical data transmission and particularly in narrowband wavelength multiplex operation.

Abstract: A device for the amplification of light including a periodic semiconductor structure composed of different layers extending in the propagation direction of the optical wave. The periodic structure is constructed of a series connection of at least two semiconductor materials having the band gaps E1 and E2 and the refractive indices n1 and n2 (e.g., E1<E2, n1>n2), can be operated as follows:as a passive interference filter;as an active, partially amplifying interference filter;as a narrow band optical amplifier;as a single-mode laser which emits only a single mode.

Abstract: A semiconductor laser is disclosed whose front or rear surface is provided with a multilayer dielectric and/or reflective coating in such a way that either a temperature-independent differential quantum efficiency or a temperature-independent power output is obtained. The sequence of layers is chosen so that the reflection coefficient decreases with increasing light wavelength. (In other laser systems, it may be necessary for the reflection coefficient to increase).