Next generation optical communications for satellites

This thesis was previously held under moratorium from 12/11/2020 to 15/11/2022The amount of data being generated and communicated in space is ever increasing. With radio frequency systems becoming increasingly strained under technological and regulatory problems, laser communications has been identified as a key technology in leading a paradigm shift within satellite communications. When compared to traditional radio satellite communications, laser communication techniques show greater performance in terms of available data rates, but also improvements in areas such as a reduction in the size, weight and power of the communication subsystem. Historically, laser communications has been demonstrated on large satellites but their current use upon small satellites (≤ 10 kg) is limited. Within this thesis we address this problem by providing a trade-off analysis for a laser transmitter within space and assess the unique environment in which these laser systems will operate. 3 new classes of optical component not previously assessed for space use are tested. A polarisation maintaining hybrid and non-polarisation maintaining hybrid component are shown to suitable for use within a low-Earth orbit environment whilst a compact 1 µm isolator needs to be assessed further. Additionally, a selection of double-clad ErYb-doped fibers are tested to select the most suitable fiber for use within future high-power applications. With a new set of parts tested, the thesis turns towards novel module development. The first module presented is a technology readiness level 5/6 design for a 0.2 W, 1 Gbps laser transmitter designed for CubeSat applications. The optical design is modelled and verified over a temperature range of -5 °C to +50 °C. Finally a multi-channel optical amplifier used for photonic-based radio frequency beam-forming is presented. This amplifier utilises a novel photonic-crystal fiber which was then integrated into a module and performance verified. Having demonstrated the potential for laser communications in small satellite applications. This thesis has helped to provide a technological base on which the nextgeneration of compact, optical communication payloads can be built.The amount of data being generated and communicated in space is ever increasing. With radio frequency systems becoming increasingly strained under technological and regulatory problems, laser communications has been identified as a key technology in leading a paradigm shift within satellite communications. When compared to traditional radio satellite communications, laser communication techniques show greater performance in terms of available data rates, but also improvements in areas such as a reduction in the size, weight and power of the communication subsystem. Historically, laser communications has been demonstrated on large satellites but their current use upon small satellites (≤ 10 kg) is limited. Within this thesis we address this problem by providing a trade-off analysis for a laser transmitter within space and assess the unique environment in which these laser systems will operate. 3 new classes of optical component not previously assessed for space use are tested. A polarisation maintaining hybrid and non-polarisation maintaining hybrid component are shown to suitable for use within a low-Earth orbit environment whilst a compact 1 µm isolator needs to be assessed further. Additionally, a selection of double-clad ErYb-doped fibers are tested to select the most suitable fiber for use within future high-power applications. With a new set of parts tested, the thesis turns towards novel module development. The first module presented is a technology readiness level 5/6 design for a 0.2 W, 1 Gbps laser transmitter designed for CubeSat applications. The optical design is modelled and verified over a temperature range of -5 °C to +50 °C. Finally a multi-channel optical amplifier used for photonic-based radio frequency beam-forming is presented. This amplifier utilises a novel photonic-crystal fiber which was then integrated into a module and performance verified. Having demonstrated the potential for laser communications in small satellite applications. This thesis has helped to provide a technological base on which the nextgeneration of compact, optical communication payloads can be built