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Long Range Optical Telecommunications


Lead Center: JPL

Participating Center(s): GRC, GSFC

Related Subtopic Pointer(s): Z8.02, S2.02, S2.03

The Long Range Optical Communications subtopic seeks innovative technologies in free-space optical communications for increased data volume returns from space missions in multiple domains: >100 gigabit/s cis-lunar (Earth or lunar orbit to ground), >10 gigabit/s Earth-sun L1 and L2, >1 gigabit/s per AU-squared deep space, and >100 megabit/s planetary lander to orbiter.


Proposals are sought in the following specific areas (TRL3 Phase I to mature to TRL4 to 5 in Phase II):


Flight Laser Transceivers:


  • Low-mass, high-effective isotropic radiated power (EIRP) laser transceivers: 30 to 100 cm clear aperture diameter telescopes for laser communications. Targeted mass less than 65 kg/square-meter with wavefront errors less than 1/25th of a wavelength at 1550 nm. Cumulative wavefront error and transmission loss not to exceed 3-dB in the far field. Advanced thermal and stray light design so that transceiver can survive direct sun-pointing and operate while pointing 3-degrees from the edge of the sun; wide range of allowable flight temperatures by the optics and structure, at least -20° C to 50° C operational range, wider range is preferred.
  • Diffraction limited field-of-view at focal plane of at least 1 milliradian radius, provision for point-ahead implementation from space.
  • Beaconless pointing subsystems for operations beyond 3 A.U.: Point 20 to 100 cm lasercomm transmitter aperture to an Earth-based receiver with a 1-sigma accuracy of better than 100 nanoradians with an assumed integrated spacecraft micro-vibration angular disturbance of 150 micro-radians (<0.1 Hz to ~500 Hz) without requiring a dedicated laser beacon transmission from Earth; lowest subsystem mass and power is a primary selection factor.
  • Low mass/low power/cold survivable optical transceivers for planetary lander to orbiter links [7]: bi-directional optical terminals with data rates from >100 megabit/second at a nominal link range of 1000 km, with an individual terminal mass <5 kg and operational power < 25W, including a pointing system for at least full hemisphere coverage.
  • Terminals shall be capable of operationally surviving >500 cycles of unpowered temperature cycling from -40° C to +40° C and a 100 krad TID. Discussion of acquisition and tracking con-ops and requirements is a must.


Flight Laser Transmitters and Receivers:

  • High-gigabit/s laser transmitter and receiver optical-electronic subsystems: space qualifiable 1550 nm laser transmitter and receiver optoelectronic modulator, detection, and forward-error-correction (FEC) assemblies for data rates from 1 gigabit/s to >200 gigabits/s with power efficiencies better than 10W per gigabit/s and mass efficiencies better than 100 g per gigabit/s.
  • Radiation tolerance better than 50 Krad is required.
  • Technologies for efficient waveform modulation, detection, and synchronization and on-board low-gap-to-capacity forward-error-correction decoding are of interest.
  • Also of interest are hybrid RF-optical technologies.
  • Integrated photonic circuit solutions are strongly desired.
  • High efficiency (>20% DC-to-optical, including support electronics) space qualifiable (including resilience to photo-darkening) multi-watt Erbium Doped Fiber Amplifier (EDFA) with high gain bandwidth (> 30nm, 0.5 dB flatness) concepts will be considered. Detailed description of approaches to achieve the stated efficiency is a must. High peak-to-average powers for supporting 7-ary to 8-ary pulse position modulation (PPM).
  • Space qualifiable wavelength division multiplexing transmitters and amplifiers with 4 to 20 channels and average output power > 20W and peak-to-average power ratios >200 with >10 Gb/s channel modulation capability are also desired.


Narrow Band Pass Optical Filters:


  • Flight qualified optical narrow band pass filters with 1 to 2 cm clear aperture and 0.5 1 nm noise equivalent bandwidth with less than 1 dB transmission loss around 1064 nm or optical c-band are also required.


Ground Assets for Optical Communication:


  • Large aperture receivers for faint optical communication signals from deep space, subsystem technologies: Demonstrate innovative subsystem technologies for >10 m diameter deep space ground collector capable of operating to within 3 degrees of solar limb with a better than 10 microradian spot size (excluding atmospheric seeing contribution). Desire demonstration of low-cost primary mirror segment fabrication to meet a cost goal of less than $35K per square meter and low-cost techniques for segment alignment and control, including daytime operations.
  • 1550 nm sensitive photon counting detector arrays compatible with large aperture ground collectors with integrated time tagging readout electronics for >5 gigaphotons/s incident rate. Time resolution <100 ps 1-sigma and highest possible single photon detection efficiency, at least 50% at highest incident rate, and total detector active area > 0.2 mm2. Integrated dark rate < 5 megacount/s.
  • Cryogenic optical filters for operation at 40K with sub-nanometer noise equivalent bandwidths in the 1550 nm spectral region, transmission losses < 0.5 dB, clear aperture >35 mm, and acceptance angle >40 milliradians with out-of-band rejection of >65 dB from 0.4 to 5 microns.


For all technologies, lowest cost for small volume production (5 to 20 units) is a driver. Research must convincingly prove technical feasibility (proof-of-concept) during Phase I, ideally with hardware deliverables that can be tested to validate performance claims, with a clear path to demonstrating and delivering functional hardware meeting all objectives and specifications in Phase II.

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