APEX: Current Status of the Airborne Dispersive Pushbroom Imaging Spectrometer

ABSTRACT Over the past few years, a joint Swiss/Belgium ESA initiative resulted in a project to build a precursor mission of future spaceborne imaging spectrometers, namely APEX (Airborne Prism Experiment). APEX is designed to be an airborne dispersive pushbroom imaging spectrometer operating in the solar reflected wavelength range between 400 and 2500 nm. The system is optimized for land applications including limnology, snow, and soil, amongst others. The instrument is optimized with various steps taken to allow for absolute calibrated radiance measurements. This includes the use of a pre-and post-data acquisition internal calibration facility as well as a laboratory calibration and a performance model serving as a stable reference. The instrument is currently in its breadboarding phase, including some new results with respect to detector development and design optimization for imaging spectrometers. In the same APEX framework, a complete processing and archiving facility (PAF) is developed. The PAF not only includes imaging spectrometer data processing up to physical units, but also geometric and atmospheric correction for each scene, as well as calibration data input. The PAF software includes an Internet based web-server and provides interfaces to data users as well as instrument operators and programmers. The software design, the tools and its life cycle are discussed as well

APEX: Current Status of the Airborne Dispersive Pushbroom Imaging Spectrometer

ABSTRACT Over the past few years, a joint Swiss/Belgium ESA initiative resulted in a project to build a precursor mission of future spaceborne imaging spectrometers, namely APEX (Airborne Prism Experiment). APEX is designed to be an airborne dispersive pushbroom imaging spectrometer operating in the solar reflected wavelength range between 400 and 2500 nm. The system is optimized for land applications including limnology, snow, and soil, amongst others. The instrument is optimized with various steps taken to allow for absolute calibrated radiance measurements. This includes the use of a pre-and post-data acquisition internal calibration facility as well as a laboratory calibration and a performance model serving as a stable reference. The instrument is currently in its breadboarding phase, including some new results with respect to detector development and design optimization for imaging spectrometers. In the same APEX framework, a complete processing and archiving facility (PAF) is developed. The PAF not only includes imaging spectrometer data processing up to physical units, but also geometric and atmospheric correction for each scene, as well as calibration data input. The PAF software includes an Internet based web-server and provides interfaces to data users as well as instrument operators and programmers. The software design, the tools and its life cycle are discussed as well

Optical routers for photonic networks-on-chip

We experimentally demonstrated four- and five-port non-blocking optical routers for photonic networks-on-chip. The optical routers are based on cascaded microring resonators. New topology design reduces the number of microring resonators and crossings, improving the performances in terms of tuning power consumption, optical loss, crosstalk and channel uniformity of the optical routers. The efficient footprints are300×340μm2 and440×660μm2 for fourand five-port optical routers, respectively. Static spectrum tests show that the3-dB bandwidths are larger than0.12 nm and0.31 nm, the extinction ratios are larger than13 dB an d20 dB for through ports,30 dB and16 dB for drop ports, for four- and five-port optical routers, respectively. Moreover, routing functionality and signal integrity are verified by12.5 Gbps high-speed signal transmission experiments using the NRZ231-1 PRBS pattern.?2011 SPIE-OSA-IEEE

Low-voltage, high extinction ratio carrier-depletion Mach-Zehnder silicon optical modulator

As a result of the low modulation efficiency of carrier-depletion Mach-Zehnder silicon optical modulator, it always needs a high voltage around6 V, which is very difficult to supply in an integrated high-speed CMOS chip. We demonstrate a carrier-depletion Mach-Zehnder silicon optical modulator which works at a low voltage. Its coplanar waveguide electrode is carefully designed to make sure the electrical wave loss along the device is low. The device operates well at a data rate of12.5 Gb/s, whose phase-shifter length is2 mm. Voltages with the swinging amplitudes being1 V and2 V are applied to the device with the reverse bias voltages of0.5 V and0.8 V. The extinction ratios are7.67 and12.79 dB respectively.?2011 SPIE-OSA-IEEE

Demonstration of a directed optical encoder using microring-resonator-based optical switches

We propose and demonstrate a directed optical logic circuit that performs the encoding function from a 4 bit electrical signal to a 2 bit optical signal based on cascaded microring switches. The four logic input signals control the states of the switches, while the two logic outputs are given by the optical power at the output waveguides. For proof of concept, a thermo-optic switching effect is used with an operation speed of 10 kbps. (C) 2011 Optical Society of Americ

Microring-resonator-based four-port optical router for photonic networks-on-chip

We design and fabricate a four-port optical router, which is composed of eight microring-resonator-based switching elements, four optical waveguides and six waveguide crossings. The extinction ratio is about 13 dB for the through port and larger than 30 dB for the drop port. The crosstalk of the measured optical links is less than -13 dB. The average tuning power consumption is about 10.37 mW and the tuning efficiency is 5.398 mW/nm. The routing functionality and optical signal integrity are verified by transmitting a 12.5 Gb/s PRBS optical signal. (C) 2011 Optical Society of Americ

Five-port optical router for photonic networks-on-chip

We experimentally demonstrate a spatially non-blocking five-port optical router, which is based on microring resonators tuned through the thermo-optic effect. The characteristics of the microring-resonator-based switching element are investigated to achieve balanced performances in its two output ports. The optical router is fabricated on the SOI platform using standard CMOS processing. The effective footprint of the device is about 440x660 mu m(2). The microring resonators have 3-dB bandwidths of larger than 0.31 nm (38 GHz), and extinction ratios of better than 21 dB for through ports and 16 dB for drop ports. Finally, 12.5 Gbps high-speed signal transmission experiments verify the routing functionality of the optical router. (C) 2011 Optical Society of Americ