Broadband superluminescent diodes with bell-shaped spectra emitting in the range from 800 to 900 nm

Abstract

Advanced manufacturing processes require improving dimensional metrology applications to reach a nanometric accuracy level. Such measurements may be carried out using conventional highly accurate roundness measuring machines. On these machines, the metrology loop goes through the probing and the mechanical guiding elements. Hence, external forces, strain and thermal expansion are transmitted to the metrological structure through the supporting structure, thereby reducing measurement quality. The obtained measurement also combines both the motion error of the guiding system and the form error of the artifact. Detailed uncertainty budgeting might be improved, using error separation methods (multi-step, reversal and multi-probe error separation methods, etc), enabling identification of the systematic (synchronous or repeatable) guiding system motion errors as well as form error of the artifact. Nevertheless, the performance of this kind of machine is limited by the repeatability level of the mechanical guiding elements, which usually exceeds 25 nm (in the case of an air bearing spindle and a linear bearing). In order to guarantee a 5 nm measurement uncertainty level, LNE is currently developing an original machine dedicated to form measurement on cylindrical and spherical artifacts with an ultra-high level of accuracy. The architecture of this machine is based on the 'dissociated metrological technique' principle and contains reference probes and cylinder. The form errors of both cylindrical artifact and reference cylinder are obtained after a mathematical combination between the information given by the probe sensing the artifact and the information given by the probe sensing the reference cylinder by applying the modified multi-step separation method.

Fabrication and characteristics of high speed InGaAs/GaAs quantum-wells superluminescent diode emitting at 1053 nm

“…To increase the SLD spectral width, some efforts have been made using quantum wells (QW) and quantumdashes (Qdash) [7], stacked twin active layers [8], asymmetric dual quantum wells [9], and self-assembled QDs [3]. Most researches on SLD focus on ∼0.8 μm [10], ∼1.3 μm [11] and ∼1.5 μm [12] wavelength. However, there are few discussions on the modulation bandwidth of SLDs.…”