Michel Maignan

Microwave photonics cross-connect repeater for telecommunication satellites

The proof-of-concept demonstration of an microwave photonics cross-connect for telecom satellite repeaters is reported. The system includes optical distribution of a high-purity local oscillator at 26 GHz, frequency down-conversion from 30 to 4 GHz, and optical cross-connection of microwave signals.

Interest of the superconductivity at 30 GHz: application to the HTS preselect receive filters for satellite communications

The objective of this study is to show the interest of superconductivity at 30 GHz compared to traditional planar technologies used at ambient and low temperatures. This paper presents the design and the measures at 77 K of high temperature superconducting (HTS) preselect receive filters for satellite communication. Comparisons of HTS and metal based planar filters have shown the performance gap between both at 30 GHz.

A nonuniform thermal de-embedding approach for cryogenic on-wafer high-frequency noise measurements

A methodology to perform accurate on-wafer high-frequency noise measurements at cryogenic temperatures (77K) is presented. In this work, the distribution of the temperature along probes and cables at low temperatures is carefully taken into account in the de-embedding process using a 3-D thermal modelling software (/spl reg/ANSYS) and thermal measurements. Cables and probes are modelled in /spl reg/ADS software using a distributed RLCG network associated to this temperature distribution. The validity of this model has been checked by measuring the noise power of a 50 /spl Omega/ on-wafer resistance placed at several low temperatures. Finally, we apply this technique to the noise characterization of sub-100 nm gates length MM-HEMT at 77K and 173K.

Applications of Optical Techniques in Future Communication Payloads

Optics and photonics bring unusual but attractive and performing solutions for implementing functions in communication payload. For the time being, these techniques have been mostly put aside for various reasons, but the technical world changing very fast, it is advisable to check if they could be competitive alternatives. Moreover, new functions will appear in the next generation of broadband satellites in response to the increasing needs for bandwidth, connectivity and flexibility. Optical techniques should be both viable solutions to enhance existing functions and the only solutions to create the new functions of broadband satellites to come. Alcatel Space research department has identified functions and equipment where optical techniques could be either a significant and necessary breakthrough or simply a technical and cost improvement. For mid term, Alcatel Space has selected and studied three functions where optics is particularly attractive for performances, mass saving and cost. First application is backplane interconnections. This technology allows gigabit connections required inside onboard large digital processors. A second application is the transport and distribution of microwaves onto optical fibers. Fibers are an interesting substitution for coaxial harness in payloads. Associated with the emerging Optical Micro-Electro-Mechanical Systems (OMEMS), this technique will extend the routing capability of payloads. A third application is intrasatellite data link. Optic fibers or wireless infrared links are promising choices to build onboard data handling system. In the long term, optical techniques could change the very aspect of repeaters and antennas of communication payloads. However, the introduction of optics for space applications is neither easy nor rapid. This paper summarizes Alcatel Space research effort and the main results in this domain. I. Optics in broadband payloads In the next five to ten years, satellite operators are anticipating the creation of a new market for satellite: broadband communications. Typically, broadband systems should offer high data rate connections to very large numbers of low price terminals. The present generation of satellite is not really suited for broadband missions involving millions of end users. Ku and C bands are too congested to offer sufficient room for growth. Receive performances of the satellite are not sized for the use of small and power limited terminals. Multiple access schemes are not adapted, as there are, for managing tens of thousand simultaneous links. A new family of satellite shall be designed to cope with these unusual requirements. Lastly, to be economically viable, communication price shall be as low as possible. Only satellites with very large capacity in term of bandwidth or number of circuits would achieve low communication price. Several techniques are investigated to increase significantly the satellite capacity [1]. Broadband payloads will have complex multi-beam antennae, hundreds of channels to receive, to route and to transmit, large onboard processors for regenerating and switching digital signals... Optics and photonics bring unusual but attractive and performing solutions for implementing these functions. Optical techniques should be viable solutions to enhance existing functions in mid term. In the long term, optical techniques will be the only solution to create the new functions of the broadband satellites to come. II. Mid term utilization of optical techniques In mid term, optical techniques could complete or replace existing functions in communication payloads: digital intra-satellite links (Onboard Data Handling System), microwaves on optical fibers, gigabit backplane interconnections in high throughput On-Board Processor (OBP), high speed data packet switching, inter-satellite and inter-orbit links, pyrotechnic harness, signal interfaces of cryogenic electronic units... 21st International Communications Satellite Systems Conference and Exhibit AIAA 2003-2297 Copyright

Optical distribution of local oscillators in future telecommunication satellite payloads

The distribution of high spectral purity reference signals over optical fibre in future telecommunication satellite payloads is presented. Several types of applications are considered, including the distribution of a reference frequency at 10 MHz (Ultra-Stable Reference Oscillator) as well as the distribution of a radiofrequency oscillator around 800 MHz (Master Local Oscillator). The results of both experimental and theoretical studies are reported. In order to meet phase noise requirements for the USRO distribution, the use of an optimised receiver circuit based on an optically synchronised oscillator is investigated. Finally, the optical distribution of microwave local oscillators at frequencies exceeding 20 GHz is described. Such a scheme paves the way to more advanced sub-systems involving optical frequency-mixing and optical transmission of microwave signals, with applications to multiple-beam active antennas.

Multi-gigabit optical interconnects for next-generation on-board digital equipment

Parallel optical interconnects are experimentally assessed as a technology that may offer the high-throughput data communication capabilities required to the next-generation on-board digital processing units. An optical backplane interconnect was breadboarded, on the basis of a digital transparent processor that provides flexible connectivity and variable bandwidth in telecom missions with multi-beam antenna coverage. The unit selected for the demonstration required that more than tens of Gbit/s be supported by the backplane. The demonstration made use of commercial parallel optical link modules at 850 nm wavelength, with 12 channels running at up to 2.5 Gbit/s. A flexible optical fibre circuit was developed so as to route board-to-board connections. It was plugged to the optical transmitter and receiver modules through 12-fibre MPO connectors. BER below 10-14 and optical link budgets in excess of 12 dB were measured, which would enable to integrate broadcasting. Integration of the optical backplane interconnect was successfully demonstrated by validating the overall digital processor functionality.

A flexible telecom satellite repeater based on microwave photonic technologies

Future telecom satellite based on geo-stationary Earth orbit (GEO) will require advanced payloads in Kaband so as to receive, route and re-transmit hundreds of microwave channels over multiple antenna beams. We report on the proof-of-concept demonstration of a analogue repeater making use of microwave photonic technologies for supporting broadband, transparent, and flexible cross-connectivity. It has microwave input and output sections, and features a photonic core for LO distribution, frequency down-conversion, and cross-connection of RF channels. With benefits such as transparency to RF frequency, infinite RF isolation, mass and volume savings, such a microwave photonic cross-connect would compare favourably with microwave implementations, and based on optical MEMS switches could grow up to large port counts.

Thermal de-embedding procedure for cryogenic on-wafer high-frequency noise measurement

The main objectives of this work concerns the on-wafer high frequency noise measurements of low noise transistors (GaAs and InP HEMTs) at cryogenic temperature. We propose a new approach to de-embed the measured noise figure or noise power by taking into account the temperature distribution of the whole bench. For measurements at 77K, the gradient of temperature between the DUT and the receiver or the noise source is greater than 200K and the temperature distribution along the probes and cables is non uniform. This temperature distribution has to be accurately known to de-embed the measured noise figure and especially for low noise device like lattice-matched or metamorphic HEMTs. The temperature distribution along the probes and cables is obtained using a 3-D thermal modeling (ANSYS) and has been checked through thermal sensors measurements. The inputs of the thermal simulations are the material composition and associated thermal properties of the probes, connectors and cables. This temperature distribution associated to a RLCG transmission line are afterwards implemented in CAD tool (ADS). In order to check the validity of such model, we have measured the noise power of a 50 Ω resistance for different temperatures (77 K to 295 K). At 77 K, after a de-embedding procedure using the distributed temperature model, we obtain an equivalent noise temperature of the resistance of 77 K ± 10 K. This de-embedding method will be applied to extract the noise parameters of cooled down HEMTs.

Novel superconductive self-equalized planar filter configuration for C-band input multiplexers: Research Articles

This paper presents recent advances in the areas of modeling, design, and fabrication of microwave filters for space applications. A fast and accurate hybrid analysis method, combining boundary integral resonant mode expansion (BI-RME) and integral equation (IE) techniques, is described. Several filters used in satellite payloads have been successfully designed, manufactured, and measured.