BRITESPACE: Project Description

The final goal of BRITESPACE project is the realization of an Integrated Path Differential Absorption (IPDA) LIDAR system based on a high performance semiconductor laser source for the measurement of carbon dioxide concentration in the Earth atmosphere from satellite based space missions.

IPDA LIDAR basically works on the use of two different wavelengths for the measurement of CO2 concentration: one wavelength is strongly absorbed (λ_OFF) and the other is lightly absorbed by the gas (λ_ON). Additionally, the laser light is modulated or pulsed in order to allow the measurement of the height of the air column under measurement.

The ON OFF wavelengths require firm frequency stability, high power and good beam quality for efficient working of the complete system. This will be obtained using with the basic building block of the project: a monolithic Master Oscillator Power Amplifier (MOPA), consisting of a frequency stabilized Distributed Feedback (DFB) Master Oscillator section and a multi section tapered semiconductor Power Amplifier. Two MOPAs will be used, one for each wavelength.

The Laser Chips will be mounted on a space compatible Laser Module, including the temperature stabilization circuit and the beam forming optics. The complete Laser Transmitter will consist of the Laser Module, the frequency stabilization unit and the control electronics.

The entire laser source will be designed so that it can be used as the transmitter unit of a Random Modulated CW LIDAR system, enabling measurements of the atmospheric CO2 concentration, with no signal ambiguity over a distance of 30 km and accuracy in distance determination better than 10 m.

As a proof of concept, the CO2 concentration along a 2-3 km test path will be measured on ground and compared with the results provided by an existing IPDA LIDAR system. For the ground test, the receiver unit will be developed in addition.

The achievement of the project objectives should provide a substantial progress in the availability of compact, and highly efficient laser sources for the detection and monitoring of greenhouse gases in future earth observation missions. In a more general context the project will pave the way of using high brightness semiconductor lasers in space applications requiring simultaneously high power, beam quality and spectral purity.