BRDFs acquired by directional radiative measurements during EAGLE and AGRISAR

Radiation is the driving force for all processes and interactions between earth surface and atmosphere. The amount of measured radiation reflected by vegetation depends on its structure, the viewing angle and the solar angle. This angular dependence is usually expressed in the Bi-directional Reflectance Distribution Function (BRDF). This BRDF is not only different for different types of vegetation, but also different for different stages of the growth. The BRDF therefore has to be measured at ground level before any satellite imagery can be used the calculate surface-atmosphere interaction. The objective of this research is to acquire the BRDFs for agricultural crop types. A goniometric system is used to acquire the BRDFs. This is a mechanical device capable of a complete hemispherical rotation. The radiative directional measurements are performed with different sensors that can be attached to this system. The BRDFs are calculated from the measured radiation. In the periods 10 June - 18 June 2006 and 2 July - 10 July 2006 directional radiative measurements were performed at three sites: Speulderbos site, in the Netherlands, the Cabauw site, in the Netherlands, and an agricultural test site in Goermin, Germany. The measurements were performed over eight different crops: forest, grass, pine tree, corn, wheat, sugar beat and barley. The sensors covered the spectrum from the optical to the thermal domain. The measured radiance is used to calculate the BRDFs or directional thermal signature. This contribution describes the measurements and calculation of the BRDFs of forest, grassland, young corn, mature corn, wheat, sugar beat and barley during the EAGLE2006 and AGRISAR 2006 fieldcampaigns. Optical BRDF have been acquired for all crops except barley. Thermal angular signatures are acquired for all the crop

High-bandwidth uni-traveling carrier waveguide photodetector on an InP-membrane-on-silicon platform

A uni-traveling carrier photodetector (UTC-PD), heterogeneously integrated on silicon, is demonstrated. It is fabricated in an InP-based photonic membrane bonded on a silicon wafer, using a novel double-sided processing scheme. A very high 3 dB bandwidth of beyond 67 GHz is obtained, together with a responsivity of 0.7 A/W at 1.55 μm wavelength. In addition, open eye diagrams at 54 Gb/s are observed. These results promise high speed applications using a novel full-functionality photonic platform on silicon

A novel optically wide-band electro-absorption modulator based on bandfilling in n-InGaAs

We propose a novel membrane electro-absorption modulator (EAM) integrated on silicon. The device is based on the carrier-concentration dependent absorption of highly-doped n-InGaAs. The modulator is predicted to be wide-band and to provide an extinction ratio (ER) of 7.5 dB, an insertion loss (IL) of 1.1 dB, a modulation speed above 10 Gbit/s and a power consumption of 80 fJ/bit. The modulator has a small footprint of 10 x 120 μm² and operates with a 1.5 V voltage swing

Uniform planarization technique for the realization of a twin-guide membrane laser

The InP Membrane on Silicon (IMOS) generic technology promises high index contrast photonic integrated circuits. To make this a reality fabrication of an electrically pumped twin-guide laser is pursued. In this paper, one of the bottle-necks for the processing is discussed, the planarization step and subsequent etch-back. Benzocyclobutene (BCB) is used to planarize SOA structures before contacting. Complete curing of BCB at 280oC creates uniformity issues during etch-back. To mitigate this, a partial cure at 180oC before the etch-back and a complete cure afterwards is performed. Experiments show repeatability and reproducibility. Good uniformity after etch-back is found