We review some usual laser range finding techniques for industrial applications. After outlining the basic principles of triangulation and time of flight [pulsed, phase-shift and frequency modulated continuous wave (FMCW)], we discuss their respective fundamental limitations. Selected examples of traditional and new applications are also briefly presented.
Intersubband transitions in n-doped multi-quantum-well semiconductor heterostructures make it possible to engineer one of the largest known nonlinear optical responses in condensed matter systems--but this nonlinear response is limited to light with electric field polarized normal to the semiconductor layers. In a different context, plasmonic metasurfaces… (More)
A novel long-wavelength vertical-cavity surface-emitting laser (VCSEL) structure based on a subwavelength high-contrast grating (HCG) as the output mirror has been realized. By design, these devices are highly polarization stable, are single mode at large apertures, and solve the VCSEL-mirror problem at long wavelengths in an elegant way. With… (More)
1.55-µm vertical cavity surface-emitting low-parasitic lasers show open eyes up to 22-Gb/s modulation speed. Uncooled error-free operation over a wide temperature range up to 85°C under constant bias conditions is demonstrated at 12.5-Gb/s data rate. At these fixed bias conditions the laser characteristics are practically invariant with temperature. These… (More)
spatial profi le. Gradient metasurfaces provide a much richer control of the wave-front in both local amplitude and phase of the emerging transmitted and refl ected beams. [ 4–7 ] Such structures enable fl at optical components for beam focusing, polarization control and phase correction, to name a few examples. [ 4–9 ] The next challenge and exciting… (More)
— We present experimental results on a short-wavelength quantum cascade laser based on intracavity second-harmonic generation. Our devices consist of an injectorless quantum cascade laser, which serves as a pump, and a transversely integrated passive two-well nonlinear section. The presented devices demonstrate above 1 mW output power at 2.65 µm emission… (More)
Preface This dissertation is a summary and a precious memory of my research in the Institute of Microwave Engineering and Photonics of the Technische Universität Darmstadt. First of all I would like to express my gratitude to my supervisor Prof. Dr.-Ing. Peter Meißner. My sincere appreciation goes also to my co-examiner Prof. Dr.-Ing. Helmut F. Schlaak. For… (More)
Optical methods are one of the painless and promising techniques that can be used for blood glucose predictions for diabetes patients. The use of thermally tunable vertical cavity surface-emitting lasers (VCSELs) as the light source to obtain blood absorption spectra, along with the multivariate technique partial least squares for analysis and glucose… (More)