701 research outputs found
Design and fabrication of a tunable InP-based VCSEL using a electro-optic index modulator
International audienceWe present the first vertical surface emitting laser (VCSEL) operating at 1.55-ÎŒm comprising a electro-optic modulator inside its cavity. This material consists of nematic liquid crystal dispersed in a polymer material (nano-PDLC). This first VCSEL exhibits a 10 nm tuning range and an excellent side-mode suppression ratio higher than 20 dB over the whole spectral range. The device is formed by a conventional InP-based active region with an epitaxial and a dielectric Bragg mirror. The nano-PDLC layer length, close to 6 ÎŒm, is in agreement with a tunable laser emission without mode-hopping. Another decisive advantage, compared to mechanical solutions, is the tuning response time which is close to a few 10 ÎŒs to scan the full spectral range, making this device appropriate for some access network functions. This first version is optically pumped and requires 170 volts to obtain a 10 nm tunability
Long-wavelength Vertical-Cavity Surface-Emitting Laser using an electro-optic index modulator with 10-nm tuning range
International audienceWe demonstrate an original approach to achieving a tunable 1.55-”m vertical-cavity surface-emitting laser. The tunability is based on an electro-optic index modulator using nano-sized droplets of liquid crystal as a phase layer. Such an approach can produce a robust and a low-cost device. A 10-nm tuning range with less than 170V applied voltage has been demonstrated. The device is formed by a conventional InP-based active region with an epitaxial and a dielectric Bragg mirror. This optically pumped device exhibits an excellent side-mode suppression ratio of higher than 20-dB over the whole spectral range
BASTA : a 95GHz FM-ÂâCW Cloud radar
International audienceGround-based continuous observation of non-precipitating clouds and fo
1.55-”m optically pumped tunable VCSEL based on a nano-polymer dispersive liquid crystal phase modulator
International audienceWe present a new approach to achieve tunability on a 1.55 ÎŒm vertical cavity surface emitting laser (VCSEL). Tunability is achieved thanks to an electro-optic index modulator. This electro-optic material consists in a n-PDLC phase layer introduced inside the VCSEL cavity. N-PDLC comprises nematic liquid crystal dispersed in a polymer material. This first VCSEL exhibits a 10 nm tuning range and an excellent side-mode suppression ratio higher than 20 dB over the whole spectral range. The device is formed by a conventional InP-based active region with an epitaxial and a dielectric Bragg mirror. The n-PDLC layer length, close to 6 ÎŒm, is in agreement with a tunable laser emission without mode-hopping. Another decisive advantage, compared to mechanical solutions, is the tuning response time which is close to a few 10 ÎŒs to scan the full spectral range, making this device appropriate for some access network functions. Voltage values are the main limiting factor, 170 Volts have been required to obtain 10 nm tunability, but material engineering is in progress to improve this point. We presented a first version of the device optically pumped, the next version will be electrically pumped as required for access network applications targeted here
Literature Review and Case Histories of Histoplasma capsulatum var. duboisii Infections in HIV-infected Patients
African histoplasmosis during HIV infection is rare
- âŠ