Abstract:
An optically pumped tunable VCSEL swept source module has a VCSEL and a pump, which produces light to pump the VSCEL, wherein the pump is geometrically isolated from the VCSEL. In different embodiments, the pump is geometrically isolated by defocusing light from the pump in front of the VCSEL, behind the VCSEL, and/or by coupling the light from the pump at an angle with respect to the VCSEL. In the last case, angle is usually less than 88 degrees. There are further strategies for attacking pump noise problems. Pump feedback can be reduced through (1) Faraday isolation and (2) geometric isolation. Single frequency pump lasers (Distributed feedback lasers (DFB), distributed Bragg reflector lasers (DBR), Fabry-Perot (FP) lasers, discrete mode lasers, volume Bragg grating (VBG) stabilized lasers can eliminate wavelength jitter and amplitude noise that accompanies mode hopping.
Abstract:
A vertical cavity surface emitting laser (VCSEL) has a shortened overall laser cavity by combining the gain section with a distributed Bragg reflector (DBR). The overall cavity length can be contracted by placing gain structures inside the DBR. This generally applies to a number of semiconductor material systems and wavelength bands, but this scheme is very well suited to the AlGaAs/GaAs material system with strained InGaAs quantum wells as a gain medium, for example.
Abstract:
Quantum well designs for tunable VCSELs are disclosed that are tolerant of the wavelength shift. Specifically, the active region has even number of substantially uniformly spaced (¼ of the center wavelength in the semiconducting material) quantum wells.
Abstract:
A fluid sample is analysed in-line by OCT techniques. The density, size, velocity and other attributes of particles present in a fluid, oil, for example, that is flowing through a conduit.