Efficient millimetre far infrared laser emissions in different molecular systems

J Infrared Milli Terahz Waves

et al. 2010

Experimental studies on an efficient high-energy pulsed NH 3 terahertz (THz) laser pumped by a TEA CO 2 laser are presented. Pulsed THz radiation of 204 mJ with a wavelength of 151.5 μm was generated from an ammonia laser pumped by a 32 J TEA CO 2 laser tuned to the 10P(32) transition, and the photon conversion efficiency of 18% was achieved, in which the pulsed energy was measured by pyroelectric detectors. Meanwhile, the THz transmittance was measured and compared for 5 kinds of materials. Finally, regarding the THz transmittance of these materials, a phenomenon for ammonia radiations with 91 μm and 152 μm pumped by a 9R(14) line was observed: i.e. while the 152 μm THz radiation can win in competition for gain at lower pressure, the 91 μm THz radiation in contrast can prevail at higher pressure.

Section: Resultsmentioning

confidence: 94%

“…To improve THz output energy to perform THz imaging and atmospheric propagation, we designed a simple NH 3 terahertz laser system, without sophisticated metal meshes mirrors [6] in the THz cavity, and obtained strong pulsed THz radiation of more than 0.2 J.…”

Section: Introductionmentioning

confidence: 99%

An Efficient High-energy Pulsed NH3 Terahertz Laser

Zhi-Xian

J Infrared Milli Terahz Waves

et al. 2010

“…l P = 2l T ð Þ is the energy conversion efficiency in quantum limit [17]. The photon conversion efficiency at 118.8 μm was 0.29%.…”

Section: Introductionmentioning

confidence: 99%

Pulsed CH3OH Terahertz Laser Emission Pumped by a TEA CO2 Laser

Jiu

J Infrared Milli Terahz Waves

et al. 2010

A simple terahertz (THz) cavity and a TEA CO 2 laser for the optically pumped THz emission is studied experimentally. To obtain high peak power of pump laser, pressure ratios of gas mixture in the cavity of the TEA CO 2 laser are discussed. When CH 3 OH are pumped by the 9P(16) and 9P(36) CO 2 laser lines, the generation of terahertz radiation with energy as high as 353 µJ and 307 µJ are obtained, respectively. The corresponding photon conversion efficiencies are 0.705% and 0.29%. Meanwhile, higher peak power of pump laser effectively improves the photon conversion efficiency. And the optimum THz laser pressure increases with narrower pulse width of pump laser.

“…Optically pumped terahertz lasers (OPTLs) are widely used THz radiation sources because of their high power, high efficiency and wide spectral range [8][9][10][11] . These OPTLs are usually pumped by CO 2 lasers.…”

Section: Introductionmentioning

confidence: 99%

An efficient optically pumped terahertz laser without metal-mesh mirrors

et al. 2010

SPIE Proceedings

The efficiency of a simply designed optically pumped terahertz laser is studied experimentally. The terahertz laser cavity only consists of a quartz glass tube, an antireflection-coated Ge window and a SiO 2 window. The Ge crystal acts as the high-reflectivity mirror of terahertz radiation and the input coupler of pump laser instead of complicated metal-mesh mirrors. The Ge crystal is near 3 mm thick, whose exact thickness is designed according to etalon effects to maximize terahertz reflectivity. NH 3 gas is filled in the cavity as the active medium and pumped by a TEA CO 2 laser. As high as 25.9 mJ terahertz radiation at the wavelength of 151.5 μm is extracted from 1.76 J pump energy. The corresponding photon conversion efficiency of this terahertz laser reaches 41.5%. A 4.7-mm-thick GaAs crystal and a 6-mm-thick ZnSe crystal are also chosen to be the input coupler. The experimental results show that the efficiency of the Ge window is 54% and 66% higher than that of the GaAs and ZnSe windows, respectively. The reason of the higher efficiency of the Ge window is demonstrated experimentally and theoretically in this paper.