Device for generating terahertz radiation, and a semiconductor component
The invention relates to a device for generating terahertz (THz) radiation comprising a short pulse laser ( 1 ) with mode coupling to which a pump beam ( 3 ) is supplied, and comprising a semiconductor component equipped with a resonator mirror (M 4 ). This semiconductor component serves to derive the THz radiation based on incident laser pulses. The resonator mirror (M 4 ), preferably a resonator end mirror, is provided with a semiconductor layer ( 8 ), which is partially transparent to the laser radiation of the short pulse laser ( 1 ), whose absorption edge is lower than the energy of the laser radiation of the short pulse laser ( 1 ) and on which the electrodes ( 9, 10 ) that can be connected to a bias voltage source are placed in order to generate and radiate the THz radiation in the electric field.
1. A device for generating terahertz (THz) radiation having a short pulse laser with mode locking to which a pump beam is supplied, and a semiconductor component including a resonator-mirror, which semiconductor component simultaneously is designed for generating the THz radiation on the basis of impacting laser pulses, characterized in that the resonator mirror (M 4 ) is provided with a semiconductor layer ( 8 ) which is partially permeable for the laser radiation of the short pulse laser ( 1 ), the absorption edge of the semiconductor layer being below the energy of the laser radiation of the short pulse laser ( 1 ), and electrodes ( 9 , 10 ) connectable to a bias voltage source being mounted thereon so as to generate the THz radiation in the electric field and radiate it.
2. A device according to claim 1 , characterized in that the resonator mirror (M 4 ) is a resonator end mirror.
3. A device according to claim 1 , characterized in that the resonator mirror (M 4 ) is a saturable Bragg reflector ( 5 ).
4. A device according to claim 1 , characterized in that the semiconductor layer ( 8 ) is made of a semiconductor material with short recombination time for free electrons.
5. A device according to claim 1 , characterized in that the semiconductor layer ( 8 ) is a gallium-arsenide(GaAs) layer.
6. A device according to claim 5 , characterized in that the semiconductor layer ( 8 ) is a low temperature gallium-arsenide (LT-GaAs) layer.
7. A device according to claim 1 , characterised in that the semiconductor layer ( 8 ) is an aluminum-gallium-arsenide (AlGaAs) layer.
8. A device according to claim 7 , characterised in that the semiconductor layer ( 8 ) is a low temperature aluminum-gallium-arsenide (LT-AlGaAs) layer.
9. A device according to claim 1 , characterised in that a dielectric lens ( 13 ) for the emitted THz radiation is mounted on the side of the resonator mirror (M 4 ) that faces away from the electrodes ( 9 , 10 ).
10. A device according to claim 9 , characterised in that the dielectric lens ( 13 ) is made of a material selected from the group consisting of silicon, gallium-arsenide (GaAs) or the like.
11. A device according to claim 1 , characterised in that the strip-shaped, parallel electrodes ( 9 , 10 ) are spaced at a distance (D) of from 30 μm up to a few mm from each other.
12. A device according to claim 1 , characterised in that the strip-shaped electrodes ( 9 , 10 ) have a width (B) of from 5 μm up to a few 10 μm.
13. A device according to claim 1 , characterised in that the electrodes ( 9 , 10 ) are made of metal.
14. A device according to claim 13 , characterised in that the electrodes ( 9 , 10 ) are made of a metal selected from the group comprising gold, aluminum, chromium, platinum-gold-or titanium-gold-layer systems.
15. A device according to claim 1 , characterised in that the electrodes ( 9 , 10 ) are formed by doped semiconductor material electrodes connected with metallic contacts.
16. A device according to claim 1 , characterised in that at least the intensity centre of gravity of the beam cross-section ( 7 ′) of the laser beam ( 7 ) is located between the electrodes ( 9 , 10 ).
17. A device according to claim 1 , characterised in that the bias voltage source ( 16 ) is adapted to deliver variable bias voltages.
18. A semiconductor component including a resonator mirror to be used in a laser, which resonator mirror is adapted to enable mode-locked operation of the laser, wherein the semiconductor component simultaneously is designed to generate terahertz(THz) radiation on the basis of impacting laser pulses, characterised in that on the resonator mirror (M 4 ), a semiconductor layer ( 8 ) partially permeable for the laser radiation ( 7 ) is provided, the absorption edge of the semiconductor layer being below the energy of the laser radiation ( 7 ) and electrodes ( 9 , 10 ) connectable to a bias voltage source being mounted thereon in a manner known per se so as to generate the THz radiation in the electric field and radiate it.
19. A semiconductor component according to claim 18 , characterised in that the resonator mirror (M 4 ) is a resonator end mirror.
20. A semiconductor component according to claim 18 characterised in that the resonator mirror (M 4 ) is a saturable Bragg reflector ( 5 ) known per se.
21. A semiconductor component according to claim 18 , characterised in that the semiconductor layer ( 8 ) is made of a semiconductor material with short recombination time for free electrons.
22. A semiconductor component according to claim 18 , characterised in that the semiconductor layer ( 8 ) is a gallium-arsenide(GaAs) layer.
23. A semiconductor component according to claim 22 , characterised in that the semiconductor layer ( 8 ) is a low temperature gallium-arsenide (LT-GaAs) layer.
24. A semiconductor component according to claim 18 , characterised in that the semiconductor layer ( 8 ) is an aluminum-gallium-arsenide (AlGaAs) layer.
25. A semiconductor component according to claim 24 , characterised in that the semiconductor layer ( 8 ) is a low temperature aluminum-gallium-arsenide (LT-AlGaAs) layer.
26. A semiconductor component according to claim 18 , characterised in that a dielectric lens ( 13 ) e.g. made of silicon, gallium-arsenide (GaAs) or the like, for the emitted THz radiation is mounted on the side of the resonator mirror (M 4 ) that faces away from the electrodes ( 9 , 10 ).
27. A semiconductor component according to claim 26 , characterised in that the dielectric lens ( 13 ) is made of a material selected from the group consisting of silicon, gallium-arsenide (GaAs) or the like.
28. A semiconductor component according to claim 18 , characterised in that the strip-shaped, parallel electrodes ( 9 , 10 ) are spaced at a distance of from 30 μm up to a few mm from each other.
29. A semiconductor component according to claim 18 , characterised in that the strip-shaped electrodes ( 9 , 10 ) have a width of from 5 μm up to a few 10 μm.
30. A semiconductor component according to claim 18 , characterised in that the electrodes ( 9 , 10 ) are made of metal, e.g. gold, aluminum, chromium, platinum-gold- or titanium-gold-layer systems.
31. A semiconductor component according to claim 30 , characterised in that the electrodes ( 9 , 10 ) are made of metal selected from the group comprising gold, aluminum, chromium, platinum-gold- or titanium-gold-layer systems.
32. A semiconductor component according to claim 18 , characterised in that the electrodes ( 9 , 10 ) are formed by doped semiconductor material electrodes connected by metallic contacts.
33. A semiconductor component according to claim 18 , characterised in that at least the intensity centre of gravity of the beam cross-section ( 7 ′) of the laser beam ( 7 ) is located between the electrodes ( 9 , 10 ).