-Reconfigurable optoelectronic oscillator based microwave photonic front ends for second generation photonic satellite payloads.-
The Miphosat-1 project aims to demonstrate a reconfigurable microwave photonic front-end for analoque second generation satellite payloads by joining the efforts of industrial sector.
Flexible, reconfigurable and high throughput satellite (HTS) payloads with respect to frequency bands and bandwidth are of increasing importance. Such features are assisted by software defined payloads, but the higher the required capacity in satellite payloads, the higher the complexity of the payload hardware when purely electrical/microwave techniques are employed.
More specifically, satellite telecommunication payloads based on traditional RF equipment with an increase in mass, power consumption, heat dissipation and equipment count when the capacity is increased. The main challenge of the next generation of HTS is to enhance flexibility and increase payload capacity while maintaining the size, weight and power (SWaP) envelope.
According to Airbus , the next generation of Tbps HTS will carry a conventional payload of over 2000 kg, and have a power consumption of 25 W. Photonic technology can tackle these issues with the introduction of photonic payload and reduce mass and power consumption by 25% and 9%.
For this reason, microwave photonic payloads, in which microwave functionality is implemented with photonic components and subsystems are being considered. The motivation is reduction of SWaP (size, weight and power) requirements resulting from optical fibre implementations or even future use of photonic integrated circuits. Optical fibre is an excellent microwave transmission medium due to the 10 THz bandwidth around 1550 nm, very low loss (0.2 dB/km), immunity to electromagnetic interference, modulation format transparency and mechanically flexibility.
J. Anzalchi, P. Inigo, and B. Roy “Application of photonics in next generation telecommunication satellites payloads”, Proc. SPIE 10563, International Conference on Space Optics — ICSO 2014, 105633O (17 November 2017).
The remit of the project is to substitute the microwave payload forward channel architecture shown in Figure 1 with the photonic based payload shown in Figure 2. With reference to Figure 1, the signal transmitted in the FWD direction from the gateway (GW) to the satellite payload is filtered and amplified with a low noise amplifier (LNA) before being fed to the down-converter (D/C) block. The D/C comprises a Ka-band mixer and a local oscillator converting the incoming high frequency Ka-band signals (27.5-29.5 GHz) to lower frequency (19.7-20.2 GHz) ones.
The same microwave functionalities can be applied by substituting the FWD payload channel of Figure 1 with the microwave photonic architecture in Figure 2. The payload architecture for the FWD channel that is considered in the MIPHOSAT project is shown in Figure 2. The signal transmitted in the FWD direction from the GW to the satellite payload is filtered by a bandpass filter and amplified with an LNA before being converted to a modulated lightwave. An optoelectronic oscillator (OEO) serves as the LO (i.e. it is the frequency generation unit, FGU), with its output being fed to the optical input of the electro-optic modulator (EOM) block, which comprises a Ka-band Mach-Zehnder modulator. Incoming high frequency Ka-band signals (27.5-29.5 GHz) are applied to the RF drive of the EOM and are down-converted to a lower band (19.7-20.2 GHz) through subsequent photo-detection in the Optical-to-Electrical conversion (O/E) block. Hence the EOM, Optical Amplifier (OA) and O/E chain comprises the frequency conversion unit (FCU).
The four key technical objectives are:
Technical Objective 1: Development of a photonic FGU based on a dual-loop OEO technology to cover LO requirements for Ka band (16-40 GHz) using commercial off-the-shelf (COTS) components.
Technical Objective 2: Subsequent extension of the OEO-based FGU developed in TO1 by including FCU functionality. This will be achieved photonically through electro-optic mixing and by sharing a common laser source for both the FGU function and FCU function.
Technical Objective 3: Continued enhancement of the photonic FGU-FCU through the use of tunable optical filters in order to provide for a reconfigurable OEO-based FGU-FCU.
Technical Objective 4: System integration of the OEO-based reconfigurable (tunable) FGU-FCU and microwave photonic filtering unit developed in TO1 through to TO3 with the respective uplink and downlink Ka band signals.
The Project MIPHOSAT-1 ESA Contract No. 4000124371/18/NL/SC “Reconfigurable optoelectronic oscillator-based microwave photonic front ends for second generation photonic satellite payloads” is financed by the European Space Agency under the CYPRUS PECS programme.
1. G. Charalambous and S. Iezekiel, “Microwave Photonic Frequency Generation and Conversion Unit Design for Ka-band Satellite Payloads”, submitted to, 2020 International Conference of Space Optics (ICSO 2020), Antibes, France, 2020.