Abstract:
A laser made of a stack of laser diodes. The stack is inserted between two mirrors to create a laser cavity. The stack of diodes is produced by epitaxial growth of a set of semiconductor layers. The ohmic contact between two adjacent laser diodes is provided by an Esaki diode junction. The optical field of the mode created in the laser cavity is periodically cancelled at the Esaki diode junctions so as to create structures with small dimensions.
Abstract:
A capacitive detector of electromagnetic waves, comprises three electron levels, wherein an internal barrier prevents a strong coupling between two levels of two neighboring wells. During an irradiation, the electrons are excited from a first level to a second level. The electrons then relax towards a third level until they relax, by tunnel effect, towards the first level. During the transition from the first level towards the third level, a dipole is created. This dipole can be detected by a detector, through the measurement of a potential difference at the terminals of the device.
Abstract:
The oscillator comprises two resonant cavities in which a non-linear crystal (3) is situated. The incident pumping radiation Rpe follows an emitting path across the crystal, the generated signal and complementary radiation carry out numerous emitted and return paths in the cavities, hence across the crystal and are thus converted into an inverse pumping radiation on the return paths thereof. According to the invention, a device (4) is incorporated in the oscillator for reflection of a fraction of the pumping radiation equivalent to the inverse pumping radiation in the absence of the device.
Abstract:
A detector with quantum structure comprising a small-gap semiconductor material inserted between two large-gap semiconductor materials, the structure comprising a coupling grating between the wave to be detected and the detector zone constituted by the small-gap material. Under these conditions, the detector zone may have a very small thickness (typically of the order of 1,000 .ANG.) and lead to a detectivity, limited by the dark current, that is high.
Abstract:
A frequency converter can be used, in particular, to generate optical waves in the medium infrared (3.12 .mu.m) range from optical sources in the near infrared range. It comprises a heterostructure semiconductor waveguide formed by an alternation of layers of material M.sub.I and M.sub.II, at least one of these materials being a non-linear semiconductor and the plane of the layers being parallel to the direction of propagation of the electromagnetic waves in the waveguide.