Terahertz Room-Temperature Photonic Crystal Nanocavity Laser

We describe an efficient surface-passivated photonic crystal nanocavity laser, demonstrating room-temperature operation with 3-ps total pulse duration (detector response limited) and low-temperature operation with ultra-low-threshold near 9uW.Comment: 6 pages, 3 figure

Low-Threshold Surface-Passivated Photonic Crystal Nanocavity Laser

The efficiency and operating range of a photonic crystal laser is improved by passivating the InGaAs quantum well (QW) gain medium and GaAs membrane using an (NH4)S treatment. The passivated laser shows a four-fold reduction in nonradiative surface recombination rate, resulting in a four-fold reduction in lasing threshold. A three-level carrier dynamics model explains the results and shows that lasing threshold is as much determined by surface recombination losses as by the cavity quality factor (Q). Surface passivation therefore appears crucial in operating such lasers under practical conditions.Comment: 3 pages, 2 figure

Time-resolved lasing action from single and coupled photonic crystal nanocavity array lasers emitting in the telecom-band

We measure the lasing dynamics of single and coupled photonic crystal nanocavity array lasers fabricated in the indium gallium arsenide phosphide material system. Under short optical excitation, single cavity lasers produce pulses as fast as 11 ps (FWHM), while coupled cavity lasers show significantly longer lasing duration which is not explained by a simple rate equations model. A Finite Difference Time Domain simulation including carrier gain and diffusion suggests that asynchronous lasing across the nanocavity array extends the laser's pulse duration.Comment: 4 pages, 4 figure

When Being Virtuous Makes Sense: Bourgeois Ethics in the Golden Age vs. Embarrassment

Have you ever thought of virtues? Temperance, Courage, Justice, Hope, and Love, just to name a few. And, have you ever thought that they could have anything to do with economics? Economists have long ago separated the moral philosophy (ethics) and the science of choice (economics) from each other. They have supposed that economic transactions – producing goods, exchanging them in the market, and eventually consuming them – are entirely independent from the human condition

Historical Small Events and the Eclipse of Utopia:Perspectives on Path Dependence in Human Thought

Questions such as ‘What if such small companies as Hewletts and the Varians had not been established in Santa Clara County in California?’ or ‘What if Q-type keyboards had not been invented?’ are well known among economists. The questions point at a phenomenon called path dependence: ‘small events’, the argument goes, may cause the evolution of institutions to lock in to specific paths that may produce undesirable consequences. How about applying such skeptical views in economics to human ideas and thought in general? That is to say, what if we ask such questions as: what if Greek philosophy had not been interested in ‘essences’ and ‘foundations’? What if Kant had not invented the ‘thing-in-itself?’ Nature and society, according to such Platonic philosophers, can be known only if it can be shown that events are governed, regulated and characterised by ‘forms’, which are immutable, complete, and perfect in their nature. But is there an ‘essence’ that makes a man 100 per cent male? Was there really a ‘foundation’ in history that caused a proletarian revolution in Russia? What if we had pushed aside the rhetoric of utopian ideality? What if we had a worldview different than the one depicted by Thomas More in his U

The Economics of Rhetoric: On Metaphors as Institutions

The professional life of economists takes place within the boundaries of the institution of academic economics. Belonging to the in

Transient chirp in high speed photonic crystal quantum dots lasers with controlled spontaneous emission

We report on a series of experiments on the dynamics of spontaneous emission controlled nanolasers. The laser cavity is a photonic crystal slab cavity, embedding self-assembled quantum dots as gain material. The implementation of cavity electrodynamics effects increases significantly the large signal modulation bandwidth, with measured modulation speeds of the order of 10 GHz while keeping an extinction ratio of 19 dB. A linear transient wavelength shift is reported, corresponding to a chirp of less than 100 pm for a 35-ps laser pulse. We observe that the chirp characteristics are independent of the repetition rate of the laser up to 10 GHz

Ultrafast broadband tuning of resonant optical nanostructures using phase change materials

The functionalities of a wide range of optical and opto-electronic devices are based on resonance effects and active tuning of the amplitude and wavelength response is often essential. Plasmonic nanostructures are an efficient way to create optical resonances, a prominent example is the extraordinary optical transmission (EOT) through arrays of nanoholes patterned in a metallic film. Tuning of resonances by heating, applying electrical or optical signals has proven to be more elusive, due to the lack of materials that can induce modulation over a broad spectral range and/or at high speeds. Here we show that nanopatterned metals combined with phase change materials (PCMs) can overcome this limitation due to the large change in optical constants which can be induced thermally or on an ultrafast timescale. We demonstrate resonance wavelength shifts as large as 385 nm - an order of magnitude higher than previously reported - by combining properly designed Au EOT nanostructures with Ge2Sb2Te5 (GST). Moreover, we show, through pump probe measurements, repeatable and reversible, large amplitude modulations in the resonances, especially at telecommunication wavelengths, over ps time scales and at powers far below those needed to produce a permanent phase transition. Our findings open a pathway to the design of hybrid metal PCM nanostructures with ultrafast and widely tuneable resonance responses, which hold potential impact on active nanophotonic devices such as tuneable optical filters, smart windows, biosensors and reconfigurable memories

Multiplexed nanoplasmonic biosensor for one-step simultaneous detection of Chlamydia trachomatis and Neisseria gonorrhoeae in urine.

Development of rapid and multiplexed diagnostic tools is a top priority to address the current epidemic problem of sexually transmitted diseases. Here we introduce a novel nanoplasmonic biosensor for simultaneous detection of the two most common bacterial infections: Chlamydia trachomatis and Neisseria gonorrhoeae. Our plasmonic microarray is composed of gold nanohole sensor arrays that exhibit the extraordinary optical transmission (EOT), providing highly sensitive analysis in a label-free configuration. The integration in a microfluidic system and the precise immobilization of specific antibodies on the individual sensor arrays allow for selective detection and quantification of the bacteria in real-time. We achieved outstanding sensitivities for direct immunoassay of urine samples, with a limit of detection of 300 colony forming units (CFU)/mL for C. trachomatis and 1500CFU/mL for N. gonorrhoeae. The multiplexing capability of our biosensor was demonstrated by analyzing different urine samples spiked with either C. trachomatis or N. gonorrhoeae, and also containing both bacteria. We could successfully detect, identify and quantify the levels of the two bacteria in a one-step assay, without the need for DNA extraction or amplification techniques. This work opens up new possibilities for the implementation of point-of-care biosensors that enable fast, simple and efficient diagnosis of sexually transmitted infections