Dark state lasers

We propose a new type of laser resonator based on imaginary "energy-level splitting" (imaginary coupling, or quality factor Q splitting) in a pair of coupled microcavities. A particularly advantageous arrangement involves two microring cavities with different free-spectral ranges (FSRs) in a configuration wherein they are coupled by "far-field" interference in a shared radiation channel. A novel Vernier-like effect for laser resonators is designed where only one longitudinal resonant mode has a lower loss than the small signal gain and can achieve lasing while all other modes are suppressed. This configuration enables ultra-widely tunable single-frequency lasers based on either homogeneously or inhomogeneously broadened gain media. The concept is an alternative to the common external cavity configurations for achieving tunable single-mode operation in a laser. The proposed laser concept builds on a high-Q "dark state" that is established by radiative interference coupling and bears a direct analogy to parity-time (PT) symmetric Hamiltonians in optical systems. Variants of this concept should be extendable to parametric-gain based oscillators, enabling use of ultrabroadband parametric gain for widely tunable single-frequency light sources

Tunable coupled-mode dispersion compensation and its application to on-chip resonant four-wave mixing

We propose and demonstrate localized mode coupling as a viable dispersion engineering technique for phase-matched resonant four-wave mixing (FWM). We demonstrate a dual-cavity resonant structure that employs coupling-induced frequency splitting at one of three resonances to compensate for cavity dispersion, enabling phase-matching. Coupling strength is controlled by thermal tuning of one cavity enabling active control of the resonant frequency-matching. In a fabricated silicon microresonator, we show an 8 dB enhancement of seeded FWM efficiency over the non-compensated state. The measured four-wave mixing has a peak wavelength conversion efficiency of -37.9 dB across a free spectral range (FSR) of 3.334 THz ($\sim$27 nm). Enabled by strong counteraction of dispersion, this FSR is, to our knowledge, the largest in silicon to demonstrate FWM to date. This form of mode-coupling-based, active dispersion compensation can be beneficial for many FWM-based devices including wavelength converters, parametric amplifiers, and widely detuned correlated photon-pair sources. Apart from compensating intrinsic dispersion, the proposed mechanism can alternatively be utilized in an otherwise dispersionless resonator to counteract the detuning effect of self- and cross-phase modulation on the pump resonance during FWM, thereby addressing a fundamental issue in the performance of light sources such as broadband optical frequency combs

The Character and Determinants of Corporate Capital Gains

This paper analyzes how corporate capital gains taxes affect the capital gain realization decisions of firms. The paper outlines the tax treatment of corporate capital gains, the consequent incentives for firms with gains and losses, the efficiency consequences of these taxes in the context of other taxes and capital market distortions, and the response of firms to these incentives. Despite receiving limited attention, corporate capital gain realizations have averaged 30 percent of individual capital gain realizations over the last fifty years and have increased dramatically in importance over the last decade. By 1999, the ratio of net long-term capital gains to income subject to tax was 21 percent and was distributed across a variety of industries suggesting the importance of realization behavior to corporate financing decisions. Time-series analysis of aggregate realization behavior demonstrates that corporate capital gains taxes impact realization behavior significantly. Similarly, an analysis of firm-level investment and property, plant, and equipment (PPE) disposal decisions and gain recognition behavior similarly suggests an important role for these taxes in determining when firms raise money by disposing of assets and realizing gains.Capital gains; capital gains taxation; corporate taxation;

A New Redshift Interpretation

A nonhomogeneous universe with vacuum energy, but without spacetime expansion, is utilized together with gravitational and Doppler redshifts as the basis for proposing a new interpretation of the Hubble relation and the 2.7K Cosmic Blackbody Radiation.Comment: 9 pages LaTeX, no figure

Sustainable Development in the Third World: A New Paradigm?

Over the past decade \u27 Sustainable Development (SD) has emerged as the latest development catchphrase. A wide range of nongovernmental as well as governmental organizations have embraced it as the new paradigm of development. A review of the literature that has sprung up around the concept of SD indicates, however, a lack of consistency in its interpretation. More important, while the all-encompassing nature of the concept gives it political strength, its current formulation by the mainstream of SD thinking contains significant weaknesses. These include an incomplete perception of the problems of poverty and environmental degradation, and confusion about the role of economic growth and about the concept of sustainability. The purpose of this study was to identify common elements in a political economy of the environment, relating environmental change to the dynamics of ideology and policy, and at different levels of political complexity. The intention was to provide a structural analysis of the environment in which the development process illuminates environmental change at both a philosophical and material level. The problem in achieving SD was related to the overriding structures of the international economic system, which have arisen out of the exploitation of environmental resources, and which frequently operate as constraints on the achievement of long-term sustainable practices. Insufficient accounting of ecological aspects of economic growth and development has resulted from intellectual traditions, where solutions are formulated, point in different directions. Conclusions are drawn that SD involves trade-offs between biological, economic and social systems and is found in the interactive zone between these systems. There are a number of international factors that may be necessary, but insufficient, conditions for SD on a national level, including peace, debt reduction, and more propitious terms of trade. There was seen dilemmas relating to SD, including the role of growth as the unquestioned objective of economic policy

Super- and Hyperdeformed Isomeric States and Long-Lived Superheavy Elements

The recent discoveries of the long-lived high spin super- and hyperdeformed isomeric states and their unusual radioactive decay properties are described. Based on their existence a consistent interpretation is given to the production of the long-lived superheavy element with Z = 112, via secondary reactions in CERN W targets, and to the low energy and very enhanced alpha-particle groups seen in various actinide fractions separated from the same W target. In addition, consistent interpretations are suggested for previously unexplained phenomena seen in nature. These are the Po halos, the low-energy enhanced 4.5 MeV alpha-particle group proposed to be due to an isotope of a superheavy element with Z = 108, and the giant halos.Comment: 4 pages. Contribution to the 2nd Int. Conf. on the Chemistry and Physics of the Transactinide Elements (TAN 03) Napa California, November 200

Time: A Measure of Change

This dissertation examines the metaphysical nature of time by drawing on literature in epistemology of measurement. Using such literature, I defend an account of time as a measure of change. I use literature on measurement to critique other metaphysical accounts of time and argue that some current metaphysical accounts of time are inadequate as accounts of time. The inadequacies we find in these accounts of time along with various other demands we have of an account of time push us further towards accepting the account of time I offer. While I defend a particular account of time, adopting that account is not a prerequisite for recognizing the valuable practice of using literature on measurement in conversations about the nature of time. Consequently, this dissertation can be understood as having a two fold purpose: 1) a meta-argument for the practice of using literature of measurement to examine metaphysical conversations about time and 2) providing an example of this recommended practice through the defense of a particular account of time, which draws on said literature

Complex Civil-Military Operations—A U.S. Military-centric Perspective

U.S. military forces have not performed well in certain operations in recent years. The root cause of the problem is a mismatch between the demands of such operations and the organization, doctrine, and even culture of the units assigned to perform them