Input-output relations for a 3-port grating coupled Fabry-Perot cavity

We analyze an optical 3-port reflection grating by means of a scattering matrix formalism. Amplitude and phase relations between the 3 ports, i.e. the 3 orders of diffraction are derived. Such a grating can be used as an all-reflective, low-loss coupler to Fabry-Perot cavities. We derive the input output relations of a 3-port grating coupled cavity and find distinct properties not present in 2-port coupled cavities. The cavity relations further reveal that the 3-port coupler can be designed such that the additional cavity port interferes destructively. In this case the all-reflective, low-loss, single-ended Fabry-Perot cavity becomes equivalent to a standard transmissive, 2-port coupled cavity

Three-port beam splitters-combiners for interferometer applications

We derive generic phase and amplitude coupling relations for beam splitters-combiners that couple a single port with three output ports or input ports, respectively. We apply the coupling relations to a reflection grating that serves as a coupler to a single-ended Fabry-Perot ring cavity. In the impedance-matched case such an interferometer can act as an all-reflective ring mode cleaner. It is further shown that in the highly undercoupled case almost complete separation of carrier power and phase signal from a cavity strain can be achieved

Cybersecurity and Simondon's Concretization Theory: Making Software More Like a Living Organism

The cybersecurity crisis has destabilized the field of informatics and called many of its foundational beliefs into question. This paper argues that Gilbert Simondon’s theory of the origin and development of technical objects helps us identify faulty theoretical assumptions within computer science and cybersecurity. In particular, Simondon’s view is that the process of the ‘individuation’ of technical objects can have similarities with the development of living beings – a view that stands in stark contrast with hylomorphic and reductionist views of technical objects currently common in computer science. We argue that those common hylomorphic approaches to software development lead to excessive modularity in software applications, which in turn results in less secure systems. To investigate a new ontological basis of software security, we look to Simondon’s ontology to reconsider what makes a piece of software vulnerable in the first place, and we focus on two concepts in his general theory of ontogenesis – ‘individuation’ and ‘associated milieu’. By examining a case study of a malware infection attack, we show that the event of a cyberattack unleashes a ‘co-concretization’ process of software applications and their associated milieu, namely, their operating system. Both the application and the operating system evolve from an abstract form to a more concrete form by re-inventing their own interiors and re-orienting their relationship to each other. We argue that software development will be more secure if it takes inspiration from the development of living beings and refocuses on the dynamic reciprocal relationship between software applications and their technical and social environment

Mobile Healthcare Design Research: A Special Issue for Information Systems Researchers

Special Section Editorial - Mobile Decision Support and Analytics for Healthcare: Citizen, Organization, Governmental and Technological Perspective

Diffractive Optics for Gravitational Wave Detectors

All-reflective interferometry based on nano-structured diffraction gratings offers new possibilities for gravitational wave detection. We investigate an all-reflective Fabry-Perot interferometer concept in 2nd order Littrow mount. The input-output relations for such a resonator are derived treating the grating coupler by means of a scattering matrix formalism. A low loss dielectric reflection grating has been designed and manufactured to test the properties of such a grating cavity

Demonstration of 3-port grating phase relations

We experimentally demonstrate the phase relations of 3-port gratings by investigating 3-port coupled Fabry-Perot cavities. Two different gratings which have the same 1st order diffraction efficiency but differ substantially in their 2nd order diffraction efficiency have been designed and manufactured. Using the gratings as couplers to Fabry-Perot cavities we could validate the results of an earlier theoretical description of the phases at a three port grating

Cognitive phenotype and differential gene expression in a hippocampal homologue in two species of frog

The complexity of an animal's interaction with its physical and/or social environment is thought to be associated with behavioral flexibility and cognitive phenotype, though we know little about this relationship in amphibians. We examined differences in cognitive phenotype in two species of frog with divergent natural histories. The greenand- black poison frog (Dendrobates auratus) is diurnal, displays enduring social interactions, and uses spatially distributed resources during parental care. Tungara frogs (Physalaemus=Engystomops pustulosus) are nocturnal, express only fleeting social interactions, and use ephemeral puddles to breed in a lek-type mating system. Comparing performance in identical discrimination tasks, we find that D. auratus made fewer errors when learning and displayed greater behavioral flexibility in reversal learning tasks than tungara frogs. Further, tungara frogs preferred to learn beacons that can be used in direct guidance whereas D. auratus preferred position cues that could be used to spatially orient relative to the goal. Behavioral flexibility and spatial cognition are associated with hippocampal function in mammals. Accordingly, we examined differential gene expression in the medial pallium, the amphibian homolog of the hippocampus. Our preliminary data indicate that genes related to learning and memory, synaptic plasticity, and neurogenesis were upregulated in D. auratus, while genes related to apoptosis were upregulated in tungara frogs, suggesting that these cellular processes could contribute to the differences in behavioral flexibility and spatial learning we observed between poison frogs and tungara frogs

High reflectivity grating waveguide coatings for 1064nm

We propose thin single-layer grating waveguide structures to be used as high-reflectivity, but low thermal noise, alternative to conventional coatings for gravitational wave detector test mass mirrors. Grating waveguide (GWG) coatings can show a reflectivity of up to 100% with an overall thickness of less than a wavelength. We theoretically investigate GWG coatings for 1064nm based on tantala (Ta2O5) on a Silica substrate focussing on broad spectral response and low thickness

Experimental demonstration of a suspended diffractively coupled optical cavity

All-reflective optical systems are under consideration for future gravitational wave detector topologies. One approach in proposed designs is to use diffraction gratings as input couplers for Fabry–Perot cavities. We present an experimental demonstration of a fully suspended diffractively coupled cavity and investigate the use of conventional Pound–Drever–Hall length sensing and control techniques to maintain the required operating condition