Abstract: The invention concerns a passive terahertz radiation source configured to emit electromagnetic radiation having frequency in the range of 10 GHz to 50 THz and a method for generating a terahertz radiation. The passive terahertz radiation source comprises: a source of a pulsed excitation light; an emitter comprising one or more emitter elements, each emitter element comprising a semiconductor layer being arranged such that at least a portion of a first major surface of said semiconductor layer is exposed to the excitation light, wherein each emitter element is configured such that upon exposure to the excitation light, a gradient of the charge carrier density is generated in the semiconductor layer in the area of transition between a first area of the semiconductor layer and a second area of the semiconductor layer, the gradient being substantially parallel to the first major surface of the semiconductor layer.

Abstract: The invention concerns a passive terahertz radiation source configured to emit electromagnetic radiation having frequency in the range of 10 GHz to 50 THz and a method for generating a terahertz radiation. The passive terahertz radiation source comprises: a source of a pulsed excitation light; an emitter comprising one or more emitter elements, each emitter element comprising a semiconductor layer being arranged such that at least a portion of a first major surface of said semiconductor layer is exposed to the excitation light, wherein each emitter element is configured such that upon exposure to the excitation light, a gradient of the charge carrier density is generated in the semiconductor layer in the area of transition between a first area of the semiconductor layer and a second area of the semiconductor layer, the gradient being substantially parallel to the first major surface of the semiconductor layer.

Abstract: A quantum cascade laser structure in accordance with the invention comprises a number of cascades (100), each of which comprises a number of alternately arranged quantum wells (110a to 110j) and barrier layers (105 to 105j). The material of at least one quantum well (110a to 110j) as well as the material of at least one barrier layer (105 to 105j) is under mechanical strain, with the respective strain being either a tensile strain or a compression strain. The quantum wells (110a to 110j) and barrier layers (105 to 105j) are engineered in the quantum cascade laser structure in accordance with the invention so that existing strains are largely compensated within a cascade (100). In the quantum cascade laser structure in accordance with the invention, each material of the quantum wells (110a to 110j) has only one constituent material and the material of at least one barrier layer (105d, 105e, 105f) has at least two constituent materials (111a, 111b, 112a, 112b, 113a, 113b).

Abstract: A quantum cascade laser structure in accordance with the invention comprises a number of cascades (100), each of which comprises a number of alternately arranged quantum wells (110a to 110j) and barrier layers (105 to 105j). The material of at least one quantum well (110a to 110j) as well as the material of at least one barrier layer (105 to 105j) is under mechanical strain, with the respective strain being either a tensile strain or a compression strain. The quantum wells (110a to 110j) and barrier layers (105 to 105j) are engineered in the quantum cascade laser structure in accordance with the invention so that existing strains are largely compensated within a cascade (100). In the quantum cascade laser structure in accordance with the invention, each material of the quantum wells (110a to 110j) has only one constituent material and the material of at least one barrier layer (105d, 105e, 105f) has at least two constituent materials (111a, 111b, 112a, 112b, 113a, 113b).

Abstract: A quantum cascade laser structure in accordance with the invention comprises a number of cascades (100), each of which comprises a number of alternately arranged quantum wells (110a to 110j) and barrier layers (105 to 105j). The material of at least one quantum well (110a to 110j) as well as the material of at least one barrier layer (105 to 105j) is under mechanical strain, with the respective strain being either a tensile strain or a compression strain. The quantum wells (110a to 110j) and barrier layers (105 to 105j) are engineered in the quantum cascade laser structure in accordance with the invention so that existing strains are largely compensated within a cascade (100). In the quantum cascade laser structure in accordance with the invention, each material of the quantum wells (110a to 110j) has only one constituent material and the material of at least one barrier layer (105d, 105e, 105f) has at least two constituent materials (111a, 111b, 112a, 112b, 113a, 113b).

Abstract: The invention relates to a passive mode locked femtosecond laser whose ring resonator comprises the elements: a) a laser-active element 1, b) at least a dielectric mirror 2 having a negative group velocity dispersion GVD such that for a continuous part of the optical spectrum amplifieable by the laser-active element the sum of the group velocity dispersion of the mirror 2 and the positive group velocity dispersion of the laser-active element 1 is negative, i.e. ∑ n ⁢ GVD n < 0 c) two concave mirrors 21 and 22 which are spatial adjacent next to the laser-active element and which are orientated with their concave surfaces towards the laser-active element 1 and d) an optical output coupler 3.

Abstract: The microstrip line for high frequency applications has a metallic ground electrode, a metallic signal conductor and a dielectric arranged between ground electrode and signal conductor. The dielectric consists of a relaxed, more specifically pre-stretched, polymer film that is coated on one side with a self-adhesive layer.