ABSTRACT
The THz region of the electromagnetic spectrum (1 - 10 THz or k = 300 - 30 /zm) currently marks the gap between transport-based electronics and quantum-transition based photonics. Electronic devices such as Gunn diodes or resonant tunnelling diodes are limited to frequencies below ITHz [1]. On the other hand, laser diodes operate almost continuously from the blue down to the mid-infrared (20 - 750THz). Existing solid-state sources of THz radiation include mixing of two visible laser beams [2 ], transient generation of oscillating charges with fs pulses [3], or p-doped Ge lasers under high magnetic field or uniaxial stress [4]. They lack, however, the general requisites of compactness, integrability and portability needed for implementation in actual devices and suffer from one or more shortcomings like low output powers, limited tunability, or the necessity of liquid He cryogenics.
