ABSTRACT
In this paper, we present a numerical and experimental study of W3-4 photonic crystal (PhC) waveguide lasers fabricated on InP substrate. In such a PhC waveguide, the dispersion curve of the fundamental mode folds in the two-dimensional gap of the triangular lattice. Folding occurs at the Brillouin zone edge as in the case of genuine distributed feedback (DFB) lasers. Single-mode emission is presently observed in both electrical and optical pumping configurations. This behavior is attributed to the different levels of out-of-plane losses experienced by the two DFB mode components. Three-dimensional finite-difference-time-domain calculations are used to finely quantify the quality factors of the waveguide modes. The modal discrimination is shown to be reinforced when lasing occurs far from the conduction band edge. This trend is also predicted for other canonical waveguides in triangular PhCs as for instance W2-3 waveguides.
ABSTRACT
We present a method of direct measurement of spectral gain and corresponding data in photonic crystal waveguides defined in heterostructures on InP substrates. The method makes use of two photopumping beams, one for gain generation, the other for amplification probing. The results show a clear enhancement of gain at spectral regions of low-group velocity, namely at the edges of the so-called mini-stopband of a three-missing rows wide photonic crystal waveguide.
ABSTRACT
On-site investigations involving interviews with spouses, friends, coworkers, supervisors, and commanders were conducted following 37 deaths or near-deaths by drug overdose among U.S. soldiers stationed in Europe. Subjects were all active-duty soldiers put on the seriously ill list at any Army hospital with an initial diagnosis which included suspected drug overdose. Victims were typically single Black males, less than 22, high school graduates in excellent health. They had been in Germany 7-24 months, liked their jobs, and were judged better than average workers by both peers and supervisors. Fifty percent played on a unit sports team, 6 of 10 had German girlfriends, and one-third had prior disciplinary problems. Although nearly half had been previously identified as having a drug or alcohol problem, only two or three could be called addicts in even the broadest sense. Six cases were suicide gestures, and only these six cases did not involve heroin and/or alcohol. The modal case followed a party, with substantial drinking. In only 25% of the cases did the victim collapse upon injection. More often he went to bed, vomited during the night, and choked on or inhaled vomitus. The data suggest reexamination of two common myths: that heroin users comprise a very unique, albeit undesirable, sample of the general population; and that "overdose" deaths are the result of ignorance, incompetence, or indifference.
