Laser coolers are an innovative class of coolers capable of reaching cryogenics temperatures in a miniaturized, contact-less and entirely vibration free way. Hence they are considered as a potential breakthrough technology for space cryogenics, especially in the field of earth-observation missions. We have developed and successfully operated a fiber-coupled laser cooling prototype. We will present a possible architecture for the laser source that could meet space requirements and review possible alternative solutions like intra-cavity cooling and using Ho-doped fluoride crystals.
We report on the design, fabrication and testing of the first laser cryocooler prototype made in Europe. The proposed architecture is based on a 7.5%-Yb:YLF cooling crystal located at the center of an astigmatic multipass cavity. A 1020 nm, 50 W laser is fiber coupled through the first cavity mirror, allowing the laser source to be located at any distance from the cold head. Encouraging preliminary results show good coupling efficiency of the laser source, stable temperature of the crystal and a minimum achieved temperature below 150 K with only 8.8 W of laser power, leaving margins for further improvements.
Laser cooling allows vibration-free cryocooling down to 100K and appears as a promising technology for future satellite missions. We evaluate the impact of a laser cooler onboard a microsatellite on size, weight and power at platform levels and compare it to a mechanical cryocooler. Practically we intend to use a cooling head attached to the focal plane holding the instruments based on state-of-the-art cooling crystals 10 %Yb:YLF inside an astigmatic absorption cell. It will be linked by a fiber to a second system that includes the opto-electronics and laser. We will present initial results on a fiber-coupled cooling head.
We present a ground-to-space quantum key distribution (QKD) mission concept and the accompanying feasibility study for the development of the low earth orbit CubeSat payload. The quantum information is carried by single photons with the binary codes represented by polarization states of the photons. Distribution of entangled photons between the ground and the satellite can be used to certify the quantum nature of the link: a guarantee that no eavesdropping can take place. The versatile space segment is compatible with a multiple of QKD protocols, as well as quantum physics experiments.
We propose a new electrooptic antenna design using organic polymer to receive microwave signals. In this paper we present the characterization of an electrooptic organic polymer. We measured the dielectric constant at microwave frequencies, and the electrooptic coefficient. We measured values of r33 of 3.35 pm/V at 1310 nm and 1.98 pm/V at 1550 nm. The goal of the electrooptic antenna design is to obtain maximum microwave and optical interaction. We propose a novel approach based on resonance effect in both optical and microwave domain. For the optical resonance effect we use a Fabry-Perot cavity, and a patch structure as microwave resonator.
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