We present measured optical absorptivity, emissivity, and maximum solar-heated temperatures for micropatterned molybdenum. The molybdenum samples were fabricated using laser micromachining and characterized using an integrating sphere and an infrared microscope. In-air solar simulator-heated temperature results for the molybdenum samples with different microstructures are presented, and COMSOL modeling is then used to predict in-vacuum maximum temperatures. A vacuum chamber was developed to reduce the convection heat loss with a mount designed to minimize conduction loss, and a maximum measured temperature of 413°C was obtained.
In oxide-confined Vertical-Cavity Surface-Emitting Lasers (VCSELs) the single-mode radiation is desirable for many
applications. The single longitudinal mode is typical in VCSELs, however transverse optical modes can be controlled
either with a small oxide aperture size [2] or small micropillar-like etched top distributed Bragg reflectors (DBRs) [3].
However, the power radiated from single-mode VCSELs is low and it results in low transmission distance in optical
telecommunication networks. The power can be increased due to the fabrication of wider oxide aperture and wider top
DBR, but than a VCSEL becomes multimode.
Since the last decade photonic crystals had been introduced to control transverse optical modes of VCSELs [4-8]. The
PC is created by periodic modulation of the refractive index in one, two or three space directions. In the VCSELs, the PC
is positioned in top DBR and fabricated due to etching air-filled holes in the DBR. It was demonstrated that the PC
reduces the transverse optical mode number, spectral linewidth [4-8] and increases the modulation bandwidth of
VCSELs [9].
In this paper we present results of the investigated VCSELs with incorporated photonic crystals fabricated using the
focused ion beam (FIB) machine. Power versus current, spectral and modulation characteristics of VCSELs with PC are
investigated and compared to similar VCSELs with etched mesa.
In this work we present to our knowledge the first spatial and dynamical model of semiconductor vertical-cavity surface-emitting laser (VCSEL) incorporating a spatial built-in optical waveguide created by the defect in the two-dimensional photonic crystal (PC). The PC is created by an array of air-holes etched in VCSEL. Results of investigations of power versus current and dynamic characteristics of a conventional proton-implanted VCSEL and VCSELs incorporating PC defect waveguides operating with effective index and photonic band-gap guidances are presented and discussed. Results show that the VCSELs with incorporated PC between laser mirrors provide a dramatic decrease of the power of the fundamental laser mode. Application of multiple-defect photonic band-gap (PBG) waveguides provides an additional dominance of the fundamental mode, and thus, the PC creates high-power but single-mode radiation of VCSELs which is impossible in conventional VCSELs. The VCSELs with PCs made in top mirror are characterized by an extremely low power of the radiation comparing to same VCSELs without the PC. Preliminary analysis of dynamical responses of the VCSELs show that VCSELs with PCs incorporated between laser mirrors could have slightly better modulation properties than VCSELs without PCs.
In this proceedings the Finite Difference Time Domain (FDTD) and frequency domain Finite Element (FE) methods are used to model both linear chirped pulse and arbitrary chirped pulse propagation in 2D Photonic Crystal (PhC) waveguides. An in-house FDTD code has been implemented which allows the study of pulse propagation in a very direct way. The carrier wavelength of the pulse is swept across the bandwidth of a mini-stopband feature and pulse compression behaviour is observed. In the case of linear chirped pulse, both round hole and square hole PhC waveguides are studied with the latter giving increased pulse compression. An input pulse is then derived from a SOA model which has arbitrary chirp. This is passed through a mini-stop band in a narrowed W3 PhC waveguide and pulse compression is observed.
Theoretically investigated oxide-confined and proton-implanted VCSELs with incorporated single-mode defect waveguide in a two-dimensional photonic crystal. It had shown, that such defect establishes single-mode conditions in proton-implanted VCSELs omitting the gain-guidance taking place in these lasers, but same effect can be achieved in oxide-confined VCSELs with oxide layer in anti-node position. In order to check theoretical data, we fabricated a group of proton-implanted VCSELs with two-dimensional photonic crystal, but the photonic crystal did not created single-mode in practical case, probably, because of small etching depth. Experimental researches in process up to now.
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