We report on the experimental results obtained for direct intensity modulation of widely tunable sampled-grating distributed Bragg-reflector (SGDBR) lasers. These devices operate in the C-band (1525 – 1562 nm range) and are directly modulated with analog and digital signals. The results obtained show a 6-GHz small-signal bandwidth, and an undistorted EyePattern for a NRZ signal modulation with ...

This article reports on a design-based research (DBR) process for designing and implementing a computer-supported collaborative learning (CSCL) course on the data security of wireless learning environments. The study focuses on examining how university students practice data security when learning on a wireless campus, how data security aspects appear in this study and how students perceive the...

Time evolution of thermal expansion in the crystal lattice of diamond was studied on the time scale from 100 ps to 18 μs upon heating of the crystal through the entire thickness by a penetrating optical laser pulse of ≈8 ps in duration. Bragg reflectivity curves were measured at different instants of time using pump-probe high-energy-resolution x-ray diffraction with 10−8 strain sensitivity. Th...

Curriculum development for distance education (DE) practitioners is more and more focusing on practical requirements and competence development. Delphi and DACUM methods have been used at some universities. However, in the competency-based development area, these methods have been taken over by professional-task-based development in the last decade, which has not been applied in the open and di...

Appropriate design of collaborative learning activities for students using 1:1 handheld devices can lead to peer scaffolding, building up students‟ collaborative skills. Building on such prior studies in mCSCL (mobile Computer Supported Collaborative Learning), we derived Chinese-PP, a novel design of in-class mobile synchronous collaborative learning game on constructions of Chinese characters...

We present a novel high-speed transmitter consisting of a frequency modulated DBR laser and optical filters. The refractive index modulation in the phase control region of the DBR laser allows highspeed frequency modulation. The generated frequency modulated signal is converted to an intensity modulated signal using the edge of the optical filter pass band. We present theoretical simulations of...

Recent progress and achievements in creating single fundamental mode vertical cavity lasers with the technique of etching a 2dimensional pattern of photonic crystal holes into the top distributed Bragg reflector are described. A simulation method for the design of single mode lasers is described, along with accuracy and limitations in predicting modal properties in these devices. Progress in im...

Theory of Constraints has been emerging as an important tool for optimization of manufacturing/service systems. Goldratt in his first book “ The Goal ” gave the introduction on Theory of Constraints and its applications in a factory scenario. A large number of production managers around the globe read this book but only a few could implement it in their plants because the book did not explain t...

We present a short review of some optical devices based on multilayered porous silicon, which can be easily obtained by varying the formation current during the etching process. These include Bragg reflectors and Fabry–Pérot microcavities, which can be adjusted from the visible to the near infrared. The interface roughness, tragic in the case of multilayers, is studied. It can be drastically re...

The advantages of the TOC (Theory of Constraints) philosophy have been extensively documented in the literature since its introduction during the 80s. At the operational level, TOC is implemented by means of the well-known DBR (Drum-Buffer-Rope) production control system. In a multiproduct manufacturing environment, the performance of DBR is greatly affected by the dispatching rules employed in...