Quantum theory of photonic crystal polaritons

We formulate a full quantum mechanical theory of the interaction between electromagnetic modes in photonic crystal slabs and quantum well excitons embedded in the photonic structure. We apply the formalism to a high index dielectric layer with a periodic patterning suspended in air. The strong coupling between electromagnetic modes lying above the cladding light line and exciton center of mass eigenfunctions manifests itself with the typical anticrossing behavior. The resulting band dispersion corresponds to the quasi-particles coming from the mixing of electromagnetic and material excitations, which we call photonic crystal polaritons. We compare the results obtained by using the quantum theory to variable angle reflectance spectra coming from a scattering matrix approach, and we find very good quantitative agreement.Comment: Proceedings of the "8th Conference on Optics of Excitons in Confined Systems" (OECS-8), 15-17 September 2003, Lecce (Italy

Exciton polaritons in two-dimensional photonic crystals

Experimental evidence of strong coupling between excitons confined in a quantum well and the photonic modes of a two-dimensional dielectric lattice is reported. Both resonant scattering and photoluminescence spectra at low temperature show the anticrossing of the polariton branches, fingerprint of strong coupling regime. The experiments are successfully interpreted in terms of a quantum theory of exciton-photon coupling in the investigated structure. These results show that the polariton dispersion can be tailored by properly varying the photonic crystal lattice parameter, which opens the possibility to obtain the generation of entangled photon pairs through polariton stimulated scattering.Comment: 5 pages, 4 figure

ALMA imaging of SDP.81 - I. A pixelated reconstruction of the far-infrared continuum emission

We present a sub-50 pc-scale analysis of the gravitational lens system SDP.81 at redshift 3.042 using Atacama Large Millimetre/submillimetre Array (ALMA) science verification data. We model both the mass distribution of the gravitational lensing galaxy and the pixelated surface brightness distribution of the background source using a novel Bayesian technique that fits the data directly in visibility space. We find the 1 and 1.3 mm dust emission to be magnified by a factor of u_tot = 17.6+/-0.4, giving an intrinsic total star-formation rate of 315+/-60 M_sol/yr and a dust mass of 6.4+/-1.5*10^8 M_sol. The reconstructed dust emission is found to be non-uniform, but composed of multiple regions that are heated by both diffuse and strongly clumped star-formation. The highest surface brightness region is a ~1.9*0.7 kpc disk-like structure, whose small extent is consistent with a potential size-bias in gravitationally lensed starbursts. Although surrounded by extended star formation, with a density of 20-30+/-10 M_sol/yr/kpc^2, the disk contains three compact regions with densities that peak between 120-190+/-20 M_sol/yr/kpc^2. Such star-formation rate densities are below what is expected for Eddington-limited star-formation by a radiation pressure supported starburst. There is also a tentative variation in the spectral slope of the different star-forming regions, which is likely due to a change in the dust temperature and/or opacity across the source.Comment: MNRAS accepted 2015 April 1

Band structure and optical properties of opal photonic crystals

A theoretical approach for the interpretation of reflectance spectra of opal photonic crystals with fcc structure and (111) surface orientation is presented. It is based on the calculation of photonic bands and density of states corresponding to a specified angle of incidence in air. The results yield a clear distinction between diffraction in the direction of light propagation by (111) family planes (leading to the formation of a stop band) and diffraction in other directions by higher-order planes (corresponding to the excitation of photonic modes in the crystal). Reflectance measurements on artificial opals made of self-assembled polystyrene spheres are analyzed according to the theoretical scheme and give evidence of diffraction by higher-order crystalline planes in the photonic structure.Comment: to appear in PR

ALMA imaging of SDP.81 - II. A pixelated reconstruction of the CO emission lines

We present a sub-100 pc-scale analysis of the CO molecular gas emission and kinematics of the gravitational lens system SDP.81 at redshift 3.042 using Atacama Large Millimetre/submillimetre Array (ALMA) science verification data and a visibility-plane lens reconstruction technique. We find clear evidence for an excitation dependent structure in the unlensed molecular gas distribution, with emission in CO (5-4) being significantly more diffuse and structured than in CO (8-7). The intrinsic line luminosity ratio is r_8-7/5-4 = 0.30 +/- 0.04, which is consistent with other low-excitation starbursts at z ~ 3. An analysis of the velocity fields shows evidence for a star-forming disk with multiple velocity components that is consistent with a merger/post-coalescence merger scenario, and a dynamical mass of M(< 1.56 kpc) = 1.6 +/- 0.6 x 10^10 M_sol . Source reconstructions from ALMA and the Hubble Space Telescope show that the stellar component is offset from the molecular gas and dust components. Together with Karl G. Jansky Very Large Array CO (1-0) data, they provide corroborative evidence for a complex ~2 kpc-scale starburst that is embedded within a larger ~15 kpc structure.Comment: MNRAS accepted, 6th July 201

Do Indonesian Managers TIME Their Corporate Bonds?

Corporate bonds are becoming popular in Indonesian capital market due to the ongoing decline in interest rates and the increase in credit rating. Debt Market Timing Theory argues that managers try to time their bonds issuance according to the market interest rate, relatively. This paper aims to analyze the debt issuance timing profile of Indonesian public listed companies. The samples are 24 bonds issuances, which have maturity period between 3 to 7, and companies already issued more than 1 bond issued within year 2009 and 2011. The manager\u27s behavior to time government bond rates is observed in the 5 working days window, whether the corporate bonds being issued at the lowest market interest rate (i.e., government bond rates) on the window. Bootstrap method is utilized to construct counterfactual data. The research finds that 7 out of 24 bonds issuance were issued at the lowest government bond yield within the window. Indonesian public listed companies had no ability to time their bond issuances during period 2009 until 2011. This paper reveals that the frequency of bond issuances made by each Indonesian company does not necessarily determine their capability to time government bond rates. However, bootstrap is a useful and more robust tool to help assessing the debt market timing ability when the samples taken are small in numbers

Self-tuned quantum dot gain in photonic crystal lasers

We demonstrate that very few (1 to 3) quantum dots as a gain medium are sufficient to realize a photonic crystal laser based on a high-quality nanocavity. Photon correlation measurements show a transition from a thermal to a coherent light state proving that lasing action occurs at ultra-low thresholds. Observation of lasing is unexpected since the cavity mode is in general not resonant with the discrete quantum dot states and emission at those frequencies is suppressed. In this situation, the quasi-continuous quantum dot states become crucial since they provide an energy-transfer channel into the lasing mode, effectively leading to a self-tuned resonance for the gain medium.Comment: 4 pages, 4 figures, submitted to Phys. Re

A 0.2V, 7.5 μW, 20 kHz ΣΔ modulator with 69 dB SNR in 90 nm CMOS

This paper presents a frequency-to-digital ΣΔ modulator designed in a digital 90 nm CMOS process, operating with a supply voltage of 0.2V. For a 7.5 μW power consumption, the SNR is 68.9 dB and the SNDR is 60.3 dB over a 20 Hz-20 kHz bandwidth. This work shows that the SNR/SNDR performance of this kind of ΣΔ converter can be adjusted over a wide range, while maintaining a state-of-the-art figure-of-merit of 82 fJ/conversion

Hubungan Efesiensi Operasional dengan Kinerja Profitabilitas pada Sektor Perbankan yang Go Public di Bursa Efek Indonesia

Tujuan penelitian ini adalah untuk dapat mengetahui pentingnya hubungan antara tingakat efisiensi operasional dan kinerja profitabilitas perbankan di Bursa Efek Indonesia (BEI) dan untuk mejelaskan sejauh mana tingkat operasional efisiensi memberikan informasi tentang profitabilitas kinerja perbankan di Bursa Efek Indonesia (BEI). Objek penelitian ini adalah Perusahaan perbankan go public yang terdaftar di Bursa Efek Indonesia (BEI) dengan jumlah populasi sebanyak 25 bank dimana populasi ini adalah juga menjadi sampel, serta periode penelitian dari tahun 2005 sampai dengan tahun 2008. Metode analisis yang digunakan adalah Regresi Linier Berganda (Multiple Linier Regression). Hasil pengujian membuktikan bahwa variable bebas memiliki pengaruh terhadap variable terikat. Variabel CAR mempengaruhi ROA secara signifikan sedangkap MSDN dan LDR tidak berpengaruh signifikan terhadap ROA pada Perusahaan perbankan go public di Bursa Efek Indonesia