FBH shows laser diodes at Space Tech Expo Europe
Compact and robust laser systems for quantum-optical and precision experiments
Ferdinand-Braun-Institut is showing its space-compatible, ultra-narrow linewidth diode laser modules and systems along with further III-V components for satellite applications at Space Tech Expo Europe (STEE) in Bremen, November 19th to 21st, 2019
FBH has extensive experience in the development and fabrication of diode laser modules for space applications. These modules have repeatedly proven their capability in experiments carried out under zero-gravity conditions. For example, they facilitated the realisation of a Bose-Einstein condensate and the first iodine-based optical frequency reference on board a sounding rocket.
A central element of the laser modules are FBH’s laser diodes, which are integrated with optics and other passive elements with ultra-high stability and accuracy – in some cases well below 100 nm. Thanks to the institute’s micro-integration technique, the modules are robust and suited for operation in space. Moreover, they feature small dimensions of 130 x 80 x 25 mm³, a mass of only 750 g, and high performance parameters – output powers exceed 500 mW with an intrinsic line-width smaller than 1 kHz. (Pictured above is a micro-integrated master oscillator power amplifier for precision iodine spectroscopy in space.)
In close cooperation with Humboldt-Universität zu Berlin, these modules are used for integration into compact and stable laser systems for precision experiments in space. This cooperation is currently being expanded to cover further fields of integrated quantum technologies. Proof-of-concept demonstrators will be transferred from the laboratory into industrial solutions for application in quantum sensing, quantum communication, quantum simulation, and quantum computing. At its booth, FBH will present micro-integrated laser modules and a laser system that were successfully operated on a sounding rocket as part of the KALEXUS experiment.
Laser modules for satellites: from communications to climate protection
Further laser modules are developed by FBH for satellite applications. For many years, laser benches from the Ferdinand-Braun-Institut have been successfully used as pump sources in Tesat-Spacecom’s laser communication terminals. High data volumes originating from Earth observation can be transmitted particularly fast between satellites and to Earth with them. At its stand, FBH will be exhibiting a current pump laser designed for use on MERLIN. The climate satellite will measure methane concentrations in the atmosphere from 2024 onwards. The pump laser delivers an output power of more than 60 W in double pulses with a repetition rate of 20 Hz and a pulse width of 150 µs. Performance and reliability have been verified through extensive technology qualifications. Even with a long operation time of more than four billion pulses, the power degrades only insignificantly. Two of these lasers are then integrated into a module delivering a pumping power of 120 W.
Energy-efficient components for satellite communications and sensors
FBH researches further components for satellite applications in the field of microwave technology and power electronics. This includes a newly developed aluminum nitride high-speed power core that boosts the switching speed of GaN power switching transistors in half-bridge configurations. Using this technology, turn-on and turn-off switching times can be reduced by typically 50 percent. The power core also features extremely compact hetero-integration and very low parasitic oscillation effects. It is suitable for space-compatible energy converters on satellites, transforming, for example, electricity generated by solar panels quickly and efficiently to different voltage levels required for various appliances. Power converters can thus be further miniaturised thanks to the higher conversion speed. A decisive advantage, since weight is key in space.
Energy consumption and dissipated power are further critical issues when operating power amplifiers in space. FBH presents concepts for envelope tracking (ET) – a well-proven technique for increasing the efficiency of solid-state power amplifiers, which modulate the supply voltage of the RF power amplifier in accordance to the instantaneous signal envelope. Together with the European Space Agency, FBH has developed a novel ET demonstrator at 1.62 GHz for communications in space. The amplifier has a peak output power of more than 90 W with a modulation bandwidth of 40 MHz. With an 8.6 PAPR (peak-to-average power ratio) signal, the overall efficiency reaches 40 percent.
FBH has also transferred the supply modulation concept to millimetre wave amplifiers. The corresponding module consists of two identical MMICs connected in series. Each consists of a single-stage amplifier with an integrated two-stage voltage switch that modulates the supply voltage of the amplifier in discrete levels. The module operates in the 20 - 26 GHz range with 14 dB gain and more than 2 W/mm at 20 V supply voltage.