The satellite market is shifting towards smaller (micro and nanosatellites), lowered mass and increased performance platforms. Nanosatellites and picosatellites have been used for a number of new, innovative and unique payloads and missions. This trend requires new concepts for a reduced size, a better performance/weight ratio and a reduction of onboard power consumption. In this context, disruptive technologies, such as laser-optical communication systems, are opening new possibilities. This paper presents the C3PO1 system, “advanced Concept for laser uplink/ downlink CommuniCation with sPace Objects”, and the first results of the development of its key technologies. This project targets the design of a communications system that uses a ground-based laser to illuminate a satellite, and a Modulating Retro-Reflector (MRR) to return a beam of light modulated by data to the ground. This enables a downlink, without a laser source on the satellite. This architecture suits well to small satellite applications so as high data rates are potentially provided with very low board mass. C3PO project aims to achieve data rates of 1Gbit/s between LEO satellites and Earth with a communication payload mass of less than 1kilogram. In this paper, results of the initial experiments and demonstration of the key technologies will be shown.
A micro-cavity in-line Mach-Zehnder interferometer (μIMZI) is an optical sensing structure fabricated in an optical fiber. Its design allows for refractive index sensing of liquid and gas in picoliter volumes, making it suitable for biochemical and medical sensing where measured material is often scarce. The fabricated structures show satisfactory levels of sensitivity, from about 400 nm/RIU in the near-water range of solutions (nD 1.336±0.003 RIU) to about 16 000 nm/RIU for solutions in approximate range from nD = 1.35 RIU to nD = 1.4 RIU. The structures were subjected to oxygen plasma, the process which was supposed to modify physical parameters of the structures, i.e., cavity surface wettability and roughness, and in consequence their sensitivity. As a result of the oxygen plasma modification we have observed a improved wettability of the structure surface, what makes it easier to introduce liquid into the cavity and simplifies the measurement process. In the case where the plasma processing is preceded by biological layer deposition, the bottom surface of the structure is smoothed and slightly deepened, causing a shift in the transmission spectrum and change in sensitivity.
In this paper we focus on refractive index (RI) sensing properties of a micro-size In-fiber Mach-Zehnder Interferometer (μIMZI). The μIMZI structure was fabricated as a precisely controlled side opening of a single-mode fiber using a femtosecond laser. The sensitivity to RI change in the micro-cavity has been measured and two RI sensitivity regions have been found for RI 1.33-1.36 and 1.37-1.40 RIU. The sensitivity in the first region is over 12,000 nm/RIU, and in the higher RI region is close to 50% higher. The obtained structures are an excellent solution for RI sensing with negligible temperature cross-sensitivity, especially where small amounts of liquid are available, e.g. in lab-on-chip, microfluidics.
This work discusses methods of applying biological films on the surface of high-sensitive long-period grating
(LPG) in the process of developing optical fiber sensors, which allow for label-free detection. Referred techniques
prepare the surface of LPG structure for further coating with layers providing specificity of the sensor system. Presented
are two methods of fiber coating, based on self-organizing layers, which were applied on two different LPGs. Short and
thermally undemanding method was used on UV-written LPG fiber whilst heat requiring method was applied on LPG
written by arc method, with silicon nitride (SiNx) nano-coated surface. Sensitivity of fibers was testes through immersing
in liquids of various refractive indexes (RIs) and found to be 925.5 nm/RIU for UV-written and nano-coated arc-written
LPGs to be -1115.8 nm/RIU, respectively. Shifts of resonance wavelengths occurring during the processes of coating are
presented and discussed. Experiments were performed using simple instruments and in short-term proceedings and can
therefore be easily repeated as well as applied to industrial production processes. We confirmed effectiveness of both
methods and proved that selected fibers were suitable for use in each of those approaches respectively.
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