Purcell effect in the inductor-capacitor laser.

The recently demonstrated inductor-capacitor (LC) laser has a strongly subwavelength mode volume. In this Letter we investigate the Purcell effect in the LC laser resonator. An average Purcell factor of 17 is computed for the LC laser. The laser rate equations are formulated and solved for the LC laser. Evidence of a large Purcell factor in agreement with the theoretical one is obtained through comparison of the threshold and the emission characteristics of the LC laser with the rate equations.

Finite size effects in surface emitting Terahertz quantum cascade lasers.

We analyze surface-emitting distributed feedback resonators for Terahertz quantum cascade lasers fabricated from double-metal waveguides. We explain the influence on resonances and surface-emission properties of the finite length and width of the gratings in connection with absorbing boundary conditions, and show that, contrary to the infinite case, the modes on either side of the photonic band-gap have finite surface losses. The lateral design of the resonator is shown to be important to avoid transverse modes of higher order and anti-guiding effects. Experimental findings are indeed in excellent agreement with the simulations. Both modeling and fabrication can easily be applied to arbitrary gratings, of which we discuss here a first interesting example.

Distributed feedback ring resonators for vertically emitting terahertz quantum cascade lasers.

We present distributed-feedback Terahertz quantum cascade lasers operating in a double-metal ring waveguide. High power collimated emission in a single spectral mode is observed in the vertical direction. A double-slit configuration is employed to achieve both good electrical contacts and efficient power out-coupling. The optical properties of the devices are interpreted with the aid of finite element simulations.

Tolerability of inhaled N-chlorotaurine in the pig model.

BACKGROUND: N-chlorotaurine, a long-lived oxidant produced by human leukocytes, can be applied in human medicine as an endogenous antiseptic. Its antimicrobial activity can be enhanced by ammonium chloride. This study was designed to evaluate the tolerability of inhaled N-chlorotaurine (NCT) in the pig model. METHODS: Anesthetized pigs inhaled test solutions of 1% (55 mM) NCT (n = 7), 5% NCT (n = 6), or 1% NCT plus 1% ammonium chloride (NH4Cl) (n = 6), and 0.9% saline solution as a control (n = 7), respectively. Applications with 5 ml each were performed hourly within four hours. Lung function, haemodynamics, and pharmacokinetics were monitored. Bronchial lavage samples for captive bubble surfactometry and lung samples for histology and electron microscopy were removed. RESULTS: Arterial pressure of oxygen (PaO2) decreased significantly over the observation period of 4 hours in all animals. Compared to saline, 1% NCT + 1% NH4Cl led to significantly lower PaO2 values at the endpoint after 4 hours (62 +/- 9.6 mmHg vs. 76 +/- 9.2 mmHg, p = 0.014) with a corresponding increase in alveolo-arterial difference of oxygen partial pressure (AaDO2) (p = 0.004). Interestingly, AaDO2 was lowest with 1% NCT, even lower than with saline (p = 0.016). The increase of pulmonary artery pressure (PAP) over the observation period was smallest with 1% NCT without difference to controls (p = 0.91), and higher with 5% NCT (p = 0.02), and NCT + NH4Cl (p = 0.05).Histological and ultrastructural investigations revealed no differences between the test and control groups. The surfactant function remained intact. There was no systemic resorption of NCT detectable, and its local inactivation took place within 30 min. The concentration of NCT tolerated by A549 lung epithelial cells in vitro was similar to that known from other body cells (0.25-0.5 mM). CONCLUSION: The endogenous antiseptic NCT was well tolerated at a concentration of 1% upon inhalation in the pig model. Addition of ammonium chloride in high concentration provokes a statistically significant impact on blood oxygenation.

Microcavity laser oscillating in a circuit-based resonator.

Lasers based on microcavities are extremely attractive for their compactness, low power dissipation, and potential for ultrafast modulation speed. We describe an ultrasmall laser based on a subwavelength electronic inductor-capacitor (LC) resonant circuit that allows for extreme confinement of the electric field. This electrically injected laser operates at a frequency of 1.5 terahertz, and the mode volume is strongly subwavelength. The design concept of the LC resonator can be extended from the terahertz range to higher frequencies and also applied to detectors and modulators.