There are a number of parametric challenges in designing transmit optical amplifiers for the current deployment of optical communication constellations. Constellations are often aligned to channel wavelengths defined by the Space Development Agency (SDA) Tranche 1 Optical Communications Terminal Standard, which requires duplex operation at 1536.61 and 1553.33nm. We present an experimental characterisation supported by numerical modelling, of duplex operation up to 10W at both channel wavelengths and discuss performance limits. The characterisation includes power, out-of-channel amplified spontaneous emission (ASE) content and in-channel ASE content / noise figure determined from time-domain extinction measurements. For an output power of 10W, stimulated Brillouin scattering (SBS) can readily limit the delivery of optical power over relatively short fiber lengths. We also present the growth of a Stokes wave as a function of output power, delivery fiber length and fiber type experimentally. These results showing good agreement with theory, and set design limits on peak power transmission. These peak power considerations being of particular interest for pulse position modulation (PPM) encoding which are required in both the SDA and Consultative Committee for Space Data Systems (CCSDS) 142.0-B-1 standards. The CCSDS and SDA standards both require a sinusoid amplitude modulated tracking tone. We present the limits of the design space of achievable modulation depth, as function of amplifier design, modulation condition and operating wavelength & power. A good agreement between experimental and numerical results is found.
Satellite free-space optical communication offers higher data rates, lower power consumption and mass savings compared to traditional RF and microwave technologies that are currently more widely deployed. Data rates are quickly increasing; with higher data throughputs enabled if higher power optical amplifiers are available. In this paper submission, G&H discuss initial scoping work performed in project EPOS (Extremely Powerful Optical Sources), a European Space Agency (ESA) funded development programme to significantly increase the optical power available from C-Band optical amplifiers. The project will develop a 100W amplifier for spaceborne use and a 1000W combined amplifier source for ground that will be enabling components in Tbit/s links.
The High Photon Efficiency (HPE) standard is a promising approach for, low Size, Weight and Power (SWaP) optical terminal for space communications. In this paper, we report the creation of a breadboard demonstrator CCSDS compliant HPE source, capable of a Pulse Position Modulation (PPM) order of 256 with an average power of 4W and kW level peak power. The HPE source operates in the optical C-band utilising high bandwidth external intensity modulation and high power optical fibre amplifier technology to enable a range of modulation/data-rates to be accessed. Additional external phase modulation is employed as an active Stimulated Brillouin Scattering (SBS) mitigation to achieve the high output peak power requirements. This laser breadboard utilises a 19” rack enclosure allowing easy integration with a HPE transmitter demonstrator breadboard at TNO to demonstrate the combined modem and laser performance. We present testing results such as electrical to optical efficiency and optical pulse characteristics of the system under a range of modes of Continuous Wave (CW) and pulsed operation. Employing the HPE pulsed laser source, we simulated an optical link and introduce results alongside the road-map toward space qualification.
The next generation high bandwidth optical links from earth to space will requirement the development of new high power WDM sources. In this paper G&H present the latest results of their ongoing development of these sources. Namely the development and testing of a 50W optical fibre amplifier that operables across much of C-band is presented as well as a high power wavelength division multiplexer, designed to combine multiple high power amplifiers outputs into a diffraction limited beam.
We present recent progress in developing miniaturized optical transmitters and receiver amplifiers for space communications. Three C-band high-speed optical transmitter designs are presented: a bespoke 300 mW version as part of TNO’s “SmallCat” terminal to fly on-board NordSat and two variants that provide 300 mW and 3 W of optical power complying to standard cubesat form factors. In addition to these transmitters, an ultra-small form factor, high gain, low noise amplifier, for boosting received signals is presented.
The G&H PDR has been developed for ophthalmic, cardiology and skin cancer as well as industrial applications. Developed for swept laser sources. The PDR is characterized and optimized at each wave band, regardless of application. Designed as a compact module the PDR has its photodiodes completely integrated in one package using small photodiodes on a submount. All fiber optic alignment is therefore already done for the OEM – with no further optical connections required.
We present recent progress in developing miniaturized optical transmitters and receiver amplifiers for space communications. Three C-band high-speed optical transmitter designs are presented: a bespoke 300 mW version as part of TNO’s “SmallCat” terminal to fly on-board NordSat and two variants that provide 300 mW and 3 W of optical power complying to standard cubesat form factors. In addition to these transmitters, an ultra-small form factor, high gain, low noise amplifier, for boosting received signals is presented.
We report here fabrication of highly efficient in-fiber grating bandpass filters using the established UV-side- exposure technique. Various combinations of passband/stopband and transmission/rejection of single- and multi-channel filters have been produced in hydrogenated standard telecom, high Ge-doped and B/Ge-codoped fibers. Up to > 60 dB rejection stopbands ranging from -2 nm to 55 nm, and passbands with 0.02 nm - 3 nm linewidths and transmissivity up to > 90% have been achieved with these devices. By concatenating several structures, a bandpass filter has been demonstrated with a combination of a 0.16 nm passband centered in a approximately 35 nm stopband, representing the highest reported finesse of 220 for any multi-nanometer stopband filter. We also report the first application of a grating bandpass filter for suppressing timing jitter in soliton propagation system, enabling transmission of 10 ps solitons over a distance of 2700 km.
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