Toptica Photonics guidestar laser features a narrowband Raman fiber amplifier
The SodiumStar 20/2 guidestar laser uses a narrowband Raman fiber amplifier that amplifies the spectrally narrow and tunable diode laser seed at 1178 nm to approximately 35 W of optical power.
The SodiumStar 20/2 guidestar laser uses a narrowband Raman fiber amplifier that amplifies the spectrally narrow and tunable diode laser seed at 1178 nm to approximately 35 W of optical power. Frequency conversion yields <20 W of output power at the sodium resonance of 589 nm, with a linewidth of <5 MHz.
TOPTICA’s guide star laser unveiled to the public for the first time
The SodiumStar 20/2, a novel approach to guide star laser technology will be on display at the SPIE Astronomical Telescopes + Instrumentation conference in Amsterdam. This laser system was developed jointly by TOPTICA and MPB Communications of Canada and is based on the approach practiced by the laser group of the European Southern Observatory (ESO). A preproduction unit has successfully completed extensive qualification testing (performance, lifetime, climate chamber: high and low temperature, altitude, EMC, transport climate, shock and vibration) to prove that it can cope with the harsh environmental conditions at its final destination of Cerro Paranal, Chile. Four of these SodiumStar lasers will be installed in 2013 as part of the adaptive optics system of ESO’s Very Large Telescope (VLT), and are also regarded as pathfinder installations for ESO’s E-ELT, currently under planning.
The joint development of the SodiumStar 20/2 combined TOPTICA’s extensive experience in narrow-band tunable diode lasers, frequency stabilization and frequency doubling with MPBC’s knowledge of high-power fiber lasers and Raman amplification. At the core of the SodiumStar 20/2 is a narrow-band Raman fiber amplifier (EFRA) based on the EFRA technology pioneered and patented by ESO. The EFRA amplifies the spectrally-narrow and tunable diode laser seed at 1178 nm to approximately 35 Watts of optical power. Efficient frequency conversion yields more than 20 Watts of output power at the sodium resonance (589 nm) with a linewidth of less than 5 MHz. The SodiumStar 20/2 overcomes previous approaches that were, to say the least, difficult to operate in an observatory environment (cooling, gravity-invariant operation, surface temperature, altitude). The SodiumStar does not require a clean room and can be installed directly on the telescope. It features an integrated D2b sideband generation (repumper), increasing the return flux dramatically compared to existing pulsed guide star laser solutions. The technology also allows a new technique coined “remote pumping” in which the bulky and high energy consuming component of the laser can be separated up to 30 m from the lightweight (80 kg) laser head situated on the guide star launch telescope assembly.
The laser system is designed to excite resonantly the sodium atoms in the Earth’s mesosphere at an altitude of 90 km. The laser system will act as a “beacon,” enabling the adaptive optics to correct for wavefront distortions induced by turbulence in the Earth’s atmosphere. Next year, four of these robust, compact, turn-key laser systems, with active wavelength stabilization will be installed on the existing telescope structure of the VLT. These SodiumStars will serve as the backbone of the VLT Adaptive Optics Facility for many years to come.
“We are very proud that we can support the astronomical community with our laser development and commitment, possibly finding another Earth one day,” said Wilhelm Kaenders, TOPTICA’s President. “Together with MPBC, we met the challenge presented by ESO in 2009 to provide an appropriate laser source. In a short period of time we developed key technologies to overcome the laser challenge faced by ESO for more than 20 years.”
Apart from ESO, many other national and international observatories plan to equip their telescopes with state-of-the-art laser technology. Within the next few years, TOPTICA looks forward to playing a major role in this work.
TOPTICA Photonics AG and MPB Communications Inc. are Licensees of the ESO Fiber RAMAN Amplifier Technology developed and transferred by ESO (www.eso.org)
TOPTICA Photonics AG develops, manufactures, services and distributes technology-leading diode and fiber lasers and laser systems for scientific and industrial applications. Sales and service are offered worldwide through TOPTICA Germany and its subsidiary TOPTICA USA, as well as all through 14 distributors. A key point of the company philosophy is the close cooperation between development and research to meet our customers’ demanding requirements for sophisticated customized system solutions and their subsequent commercialization.
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