Evidence of noncascade intracenter electron relaxation in shallow donor centers in silicon

Noncascade relaxation of photoexcited electrons on ionized donor centers has been observed in silicon doped by arsenic (Si:As) at low temperatures. Emission spectra of the Si:As terahertz intracenter laser give evidence of specific channels for the electron relaxation through low-lying donor states. The dominating relaxation channels strongly...

Terahertz gain on shallow donor transitions in silicon

Small signal gain measurements of optically excited terahertz silicon lasers are reported. Two types of lasers, Si:P and Si:Bi, were investigated. They were optically excited with radiation from a free electron laser or a CO2 laser. The experiments were performed with an oscillator-amplifier scheme where one sample serves as a laser while the...

Some properties of a room temperature THz detection array

Detection peculiarities of an un-cooled (room temperature) 8×8 pixel array designed to image broadband THz radiation were investigated. Each pixel consists of a thin conductive film absorber on a dielectric membrane with thermopile temperature readout. It was designed and tested for four combinations of two different types of absorber and...

Phase locking and spectral linewidth of a two-mode terahertz quantum cascade laser

We have studied the phase locking and spectral linewidth of an ? 2.7?THz quantum cascade laser by mixing its two lateral lasing modes. The beat signal at about 8?GHz is compared with a microwave reference by applying conventional phase lock loop circuitry with feedback to the laser bias current. Phase locking has been demonstrated, resulting in...

Beam patterns of terahertz quantum cascade lasers with subwavelength cavity dimensions

The need to reach single-mode lasing and minimize at the same time the electrical dissipation of cryogenically operated terahertz quantum cascade lasers may result in small and subwavelength cavity dimensions. To assess the influence of such dimensions on the shape of the laser emission, we have measured the beam pattern of two metal-metal...

Stimulated terahertz stokes emission of silicon crystals doped with antimony donors

Antenna model for wire lasers

Terahertz heterodyne receiver based on a quantum cascade laser and a superconducting bolometer

We report the first demonstration of an all solid-state heterodyne receiver that can be used for high-resolution spectroscopy above 2?THz suitable for space-based observatories. The receiver uses a NbN superconducting hot-electron bolometer as mixer and a quantum cascade laser operating at 2.8?THz as local oscillator. We measure a double...

Optical Far-IR wave generation - state-of-the-art and advanced device structures

A recent study initiated by the European Space Agency aimed at identifying the most promising technologies to significantly improve on the generation of coherent electromagnetic radiation in the THz regime. The desired improvements include, amongst others, higher output powers and efficiencies at increasingly higher frequencies, wider tunability...

THz calorimetry: An absolute power meter for TeraHertz radiation and the absorptivity of the Herschel Space Observatory telescope mirror coating

A new calorimetric absolute power meter has been developed for THz radiation. This broad band THz power meter measures average power at ambient temperature and pressure, does not use a window, and is insensitive to polarization and time structure of THz radiation. The operation of the power meter is based on the calorimetric method: in order to...

Stimulated terahertz emission from group-V donors in silicon under intracenter photoexcitation

Frequency-tunable radiation from the free electron laser FELIX was used to excite neutral phosphorus and bismuth donors embedded in bulk monocrystalline silicon. Lasing at terahertz frequencies has been observed at liquid helium temperature while resonant pumping of odd parity impurity states. The threshold was about two orders of magnitude...

Transverse mode structure and output stability of the p-Ge terahertz laser

The p-Ge terahertz laser-properties under pulsed- and mode-locked operation

High-field calculations of Landau-like shallow donor states: A finite-difference approach

Landau-like states in the magneto-optical spectrum of a shallow donor impurity: Theory versus experiment

Far-infrared picosecond time-resolved measurement of the free-induction decay in GaAs:Si