2. Photonics
Photonics is the physical science of light (photon) generation,
detection, and manipulation through emission, transmission,
modulation, signal processing, switching, amplification, and sensing.
The term photonics more specifically connotes:
• The particle properties of light,
• The potential of creating signal processing device technologies using
photons,
• The practical application of optics, and
• An analogy to electronics.
3. • Photonics as a field began with the invention of the laser in 1960.
• The term photonics came into common use in the 1980s as fiber-
optic data transmission was adopted by telecommunications network
operators, the term was used widely at Bell Laboratories.
• Its use was confirmed when the IEEE Lasers and Electro-Optics
Society established an archival journal named PhotonicsTechnology
Letters at the end of the 1980s.
4. Photonic Communications
• Photonics reflects the importance of the photon nature of light. Photonics &
electronics clearly overlap since electrons often control the flow of photons &
conversely, photons control the flow of electrons.
• The scope of Photonics:
1. Generation of Light (coherent & incoherent)
2. Transmission of Light (through free space, fibers, imaging systems, waveguides)
3. Processing of Light Signals (modulation, switching, amplification, frequency
conversion )
4. Detection of Light (coherent & incoherent)
Photonic Communications: describes the applications of photonic technology
in communication devices & systems, such as transmitters, transmission media,
receivers & signal processors.
5. Photonics and Optics
• Photonics is closely related to optics.
• Photonics is related to modern optics such as quantum optics,
optomechanics, electro-optics, optoelectronics and quantum electronics.
• Quantum optics often connotes fundamental research, whereas photonics
is used to connote applied research and development.
• Photonics also relates to the emerging science of quantum information and
quantum optics.
6. Why Photonic Communications?
• Extremely wide bandwidth: high carrier frequency ( a wavelength of 1552.5 nm
corresponds to a center frequency of 193.1THz!) & consequently orders of
magnitude increase in available transmission bandwidth & larger information
capacity.
• Optical Fibers have small size & light weight.
• Optical Fibers are immune to electromagnetic interference (high voltage
transmission lines, radar systems, power electronic systems, airborne systems)
• Lack of EMI cross talk between channels
• Availability of very low loss Fibers (0.25 to 0.3 dB/km), high performance active &
passive photonic components such as tunable lasers, very sensitive
photodetectors, couplers, filters,
• Low cost systems for data rates in excess of Gbit/s.
7. Photonics in Space
The use of photonics technologies for space application presents significant
advantages due to its specific properties as follows
• Almost unlimited bandwidth (i.e. 1550nm fiber can go to severalTHz.)
• Reduced propagation losses at spacecraft level (due to short communication
distances).
• Supports any modulation or coding format
• Immunity against electromagnetic interferences,
• Optimum mechanical properties (light weight, mechanically flexible,
reduced volume, resistant against corrosion of contamination).
8. Photonics in Space
• Reduced noise generation and Electromagnetic immunity are clear
advantages in cases where satellite operation works close to the sensors
sensitivity bandwidth (i.e. natural Earth microwave emissions).
• Mechanical flexibility and low weigh of FO compared with standard hardness
are an advantage when articulated systems are used or many meters of
cabling are required.
• Mass reduction possibilities in case of using photonic systems may result in
important cost reduction during handling and launching of the S/C.
• Huge bandwidth and multiplexing properties makes FO systems is a clear
advantage for signal processing. and thermal and structure monitoring
applications.
• Optical the use of optical wireless technologies will reduce cost and time in
the Assembly andTest (AIT) phase
9. Photonics in Space
• Photonics could potentially be a key technology in the emerging
market of laser space communications, with unique performance
characteristics.
• It may enable new bandwidth-hungry applications and significantly
boost the space communications industry downstream.
• Because of advantages related to bandwidth, mass, power
consumption, beam size and immunity to electromagnetic
interference, photonic subsystems are now being considered in
navigation satellite systems, Earth observation satellites, low Earth
orbit (LEO) constellations and within telecom satellite payloads.
10. • A key milestone in the robustness of photonics was the 2009 deployment of 1.55-μm fused
fiber couplers on a mission-critical payload onboard the European Space Agency’s (ESA)
Soil Moisture and Ocean Salinity (SMOS) satellite.
• The nominal lifetime of the satellite was three years (including a six-month commissioning
phase).
• But now, more than seven years later, SMOS remains fully operational and continues to
gather information.
11. Flexible RF payloads
• Microwave photonics are being developed to offer new functionality
and performance to RF payloads.
• At the core of these payloads are photonics to generate stable local
oscillators, perform optical down conversion, and manipulate the
optical microwave signals by routing, beamforming or filtering them
in the optical domain.
• The main components of such a photonic system include: lasers,
optical amplifiers, WDM components, optical modulators, optical
switches, and photonic integrated circuits for optical beam forming,
switching and filtering.
12. Optical interconnects for digital payloads
• ESA is looking at how photonics can be used to improve the
performance of analogue to digital conversion.
• The use of low loss optical fibres also allows high density optical
interconnections making use of high density, lightweight optical fibre
harness and flexfoils for the distribution of digital signals within these
payloads, giving increased freedom to the system designers.
13. Photonic Integrated Circuits
• Photonic integrated circuits are the chip scale integration of multiple
optical elements or components which enable complex functions
analogous to the electrical integrated chips.
• As these chips increase in complexity and functionality they are finding
new space applications; micro spectrometers, integrated solid state gyro,
laser beam steering, complex optical modulation/demodulation, optical
switching, optical beam forming, packet processing.
• The main advantage of this approach is clearly to target a massive size and
weight advantage, but also to advantage of potential cost reduction
(manufacturing, assembly and qualification).
• The optoelectronics section in collaboration with European industry has
been involved in developing a number of integrated devices from
components to full systems on a chip.
14. Intra-satellite Digital Communications
• SpaceFibre is a multi-Gbits/s, on-board network technology for spaceflight
applications, which runs over electrical or fibre-optic cables.
• The Optoelectronics section together with European partners has been
developing 10Gbps optical transceivers to meet the needs of future satellites,
and have been involved in component testing and evaluation to IODs at system
level.
15. Fibre Optic Sensing for Satellite Platforms
• Fibre optic sensing is a new tool in space craft engineering, which permits the
measurement of; temperature, strain, acceleration and rotation by modulation
of some parameter of light propagating inside a fibre.
• The optoelectronics section has been exploiting these techniques to understand
how this fibre technology can be used in future space missions.
• The technologies under investigation include Fibre Bragg Gratings (FBGs),
Photonic Band Gap sensors, In-fibre interferometers (FOG, accelerometers), as
well as distributed sensing approaches using the natural scattering mechanisms
of the fibre itself which permit 1000s of measurement points per meter of the
fibre.
16. Photonics for Launchers
• Optopyrotechnics is a new approach to the detonation of pyrotechnics using
short pulses of a laser output to ignite the pyro material.
• This technology has been baselined for the next European launcher, the Ariane 6.
• The opto-electronics section together with European industry has been leading
the development of key components of this system, from the laser to the safety
features such as the optical safety barrier.
• Other photonic technologies have been studied for use in future launchers
include, laser ignition, fibre optic sensing, optical communications and optical
wireless.
17. Conclusion
If optics and photonics is to penetrate the space sector as an enabling
technology, it will need to support the transition of the space industry
to Space 2.0, while reinforcing the deployment of cost-effective, inter-
satellite networks and mega constellations.
This can be accomplished by technology spin-in from other sectors
such as telecommunications and industrial systems.
Manufacturing processes of high-reliability telecom applications could
be used as a technology baseline, and by adapting process controls and
assembly procedures, it can enable high-volume space photonic unit
assembly, integration and test.
