Inhalation of nitric oxide (NO) improved arterial oxygenation and enabled the reduction of inspired oxygen therapy and airway pressure support in patients with severe acute respiratory syndrome (SARS). In addition, chest radiography showed decreased spread or density of lung infiltrates, and the physiological effects remained after termination of inhaled NO therapy. These findings suggest not only a pulmonary vasodilator effect of inhaled NO, but also an effect on SARS.

We report on the growth and characterization of high external quantum efficiency (EQE) GaAs/ GaInP double heterostructures. By properly treating the GaAs/GaInP interface, we are able to produce structures measuring a record EQE of 99.5% 6 0.1% in GaAs. This efficiency exceeds the requirement for achieving laser cooling in GaAs. However, net cooling has not yet been realized due to residual below gap background absorption. V

External quantum efficiency of semiconductor photonic devices is directly measured by wavelengthdependent laser-induced temperature change (scanning laser calorimetry) with very high accuracy. Maximum efficiency is attained at an optimum photo-excitation level that can be determined with an independent measurement of power-dependent temperature or power-dependent photoluminescence. Time-resolved photoluminescence lifetime and power-dependent photoluminescence measurements are used to evaluate unprocessed heterostructures for critical performance parameters. The crucial importance of parasitic background absorption is discussed.External quantum efficiency (EQE or g ext ) is an important parameter that characterizes many photonic devices. It is widely used to evaluate light emitting diodes, photovoltaics, semiconductor lasers, and emerging technology such as laser-induced refrigeration of solids. 1 The essential idea is to have a single coefficient that accounts for both the efficiency of the photon-electron conversion process (internal quantum efficiency) and the efficiency of moving light into and/or out of the device (coupling efficiency). Internal quantum efficiency is deleteriously affected when electronic excitations lose energy through the production of heat. This nonradiative recombination can be mediated by phonons, interfaces, surfaces, dislocations, defects, and even other charge carriers. The light coupling efficiency is driven by Fresnel reflection and the condition of total internal reflection. This leads to photon recycling and the concomitant production of wasteful heat due to the presence of parasitic background absorption. It is often difficult to model or even anticipate how the various disparate mechanisms degrade performance. Instead, empirical data should guide device development. It is therefore crucial to have in place an experimental scheme for precision measurement of efficiency. This allows such problems to be identified and addressed systematically.There will be different descriptions of EQE and varying design goals depending on the application. A high performance solar cell, for example, must make maximum use of the available broadband spectrum and the resulting photoexcitations to produce an external current. A single color LED design, on the other hand, strives to couple the generated narrow-spectrum of light from the device. In this paper, we present a procedure for precision quantification of photoluminescence external quantum efficiency in bulk GaAs heterostructures. Device characterization is performed in the context of optical refrigeration (laser cooling in solids), where the demands on EQE are extreme. For this applica-tion, EQE is defined as the fraction of photo-excited electron-hole pairs which produce luminescence photons that escape the device into free-space. It has been established that laser-induced cooling of GaAs will occur only when EQE exceeds 99%, i.e., far greater than needed for useful operation of other semiconductor photonic devices. 2 In addition, it becomes p...

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Genetic algorithm is adopted to give an automatic design scheme for fiber-based optical parametric amplifiers (FOPAs). Main steps of the optimization process and discussion about this algorithm are presented. The results show that present FOPA has more than 300-nm flat bandwidth with a central wavelength of 1500 nm and a gain ripple of less than 0.3 dB. Meanwhile, fluctuation in zero-dispersion wavelength of fibers is taken into consideration and its influence is briefly analyzed.