Terahertz emission from lithium doped silicon under continuous wave interband optical excitation

Terahertz-range photoluminescence from silicon-germanium crystals and superlattices doped by phosphor has been studied under optical excitation by radiation from a mid-infrared CO2 laser at low temperature. SiGe crystals with a Ge content between 0.9 and 6.5 %, doped by phosphor with a concentration optimal for silicon laser operation, do not exhibit terahertz gain. On the contrary, terahertz-range gain of ~ 2.3 - 3.2 cm-1 has been observed for donor-related optical transitions in Si/SiGe strained superlattices at pump intensities above 100 kW/cm2.

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Optical Properties of Novel Vibronic Bands in Electron-Irradiated Tin Doped Silicon

MRS Proceedings ◽

10.1557/proc-163-261 ◽

1989 ◽

Vol 163 ◽

Author(s):

J. H. Svensson ◽

B. Monemar ◽

B. G. Svensson

Keyword(s):

Optical Properties ◽

Low Temperatures ◽

Excited Electronic State ◽

Electronic States ◽

Optical Excitation ◽

Electronic Transitions ◽

Vibrational States ◽

Doped Silicon ◽

Silicon Doped ◽

Excitation Conditions

AbstractThe optical absorption of two new electronic transitions in silicon doped with tin has been investigated. At low temperatures two no-phonon lines are observed at 2755.3 and 4112.2 cm-1, each with strong coupling to a single quasi-localized vibration in the excited electronic state. These vibrations have quantum energies of 69.6 and 70.2 cm-1, respectively. At higher temperatures coupling to thermally excited vibrational states in the ground electronic states is observed for both lines. The transition with the no-phonon line at 4112.2 cm-1 has been studied in detail and is found to be well described using the adiabatic and Condon approximations. The optical properties of the two transitions are found to be quite similar. Moreover the relative intensities of the two lines are found to be dependent on the optical excitation conditions.

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Recent progress in terahertz difference-frequency quantum cascade laser sources

Nanophotonics ◽

10.1515/nanoph-2018-0093 ◽

2018 ◽

Vol 7 (11) ◽

pp. 1795-1817 ◽

Cited By ~ 19

Author(s):

Kazuue Fujita ◽

Seungyong Jung ◽

Yifan Jiang ◽

Jae Hyun Kim ◽

Atsushi Nakanishi ◽

...

Keyword(s):

Active Region ◽

Quantum Cascade Laser ◽

Continuous Wave ◽

Difference Frequency Generation ◽

Difference Frequency ◽

High Resistivity ◽

Dramatic Improvement ◽

Terahertz Emission ◽

Quantum Cascade ◽

Frequency Generation

AbstractTerahertz quantum cascade laser (QCL) sources based on intra-cavity difference frequency generation are currently the only electrically pumped monolithic semiconductor light sources operating at room temperature in the 1–6-THz spectral range. Relying on the active regions with the giant second-order nonlinear susceptibility and the Cherenkov phase-matching scheme, these devices demonstrated drastic improvements in performance in the past several years and can now produce narrow-linewidth single-mode terahertz emission that is tunable from 1 to 6 THz with power output sufficient for imaging and spectroscopic applications. This paper reviews the progress of this technology. Recent efforts in wave function engineering using a new active region design based on a dual-upper-state concept led to a significant enhancement of the optical nonlinearity of the active region for efficient terahertz generation. The transfer of Cherenkov devices from their native semi-insulating InP substrates to high-resistivity silicon substrates resulted in a dramatic improvement in the outcoupling efficiency of terahertz radiation. Cherenkov terahertz QCL sources based on the dual-upper-state design have also been shown to exhibit ultra-broadband comb-like terahertz emission spectra with more than one octave of terahertz frequency span. The broadband terahertz QCL sources operating in continuous-wave mode produces the narrow inter-mode beat-note linewidth of 287 Hz, which indicates frequency comb operation of mid-infrared pumps and thus supports potential terahertz comb operation. Finally, we report the high-quality terahertz imaging obtained by a THz imaging system using terahertz QCL sources based on intra-cavity difference frequency generation.

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Room Temperature Terahertz Emission via Intracenter Transition in Semiconductors

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.500.66 ◽

2012 ◽

Vol 500 ◽

pp. 66-69 ◽

Cited By ~ 2

Author(s):

Hikari Dezaki ◽

Meng Long Jing ◽

Sundararajan Balasekaran ◽

Tadao Tanabe ◽

Yutaka Oyama

Keyword(s):

Room Temperature ◽

Continuous Wave ◽

Emission Characteristics ◽

Bulk Crystals ◽

Indirect Transition ◽

Optically Pumped ◽

Terahertz Emission ◽

Temperature Dependences ◽

Pump Lasers ◽

Intracenter Transitions

An efficient continuous wave (CW) THz source working at nominal room temperature is described. Optically pumped room temperature THz emission is observed from various kinds of semiconductor bulk crystals. In order to investigate the emission mechanism, temperature dependences of terahertz emission intensity in various semiconductors are measured. Semiconductor samples used are InSb, InSb:Ge, InAs, GaSb, Ge, and Si. From these results, it is shown that the temperature dependences of emission characteristics are different between direct and indirect transition semiconductors, and that the high resistive Ge is suitable for room temperature THz emitter via intracenter transitions excited by IR pump lasers.

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