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We report on our development of laser rack systems as “quantum enabling” building blocks of future quantum devices. We present funded projects, where such rack laser systems are integrated into first prototypes.

We report on a transportable and easy-to-operate optical clock utilizing the 2S1/2 - 2D3/2 transition of a single trapped 171Yb+ ion at 436 nm. Developed within a pilot project for quantum technology in Germany lead by industry, the clock is set up in two 19″ racks. In this way, transportation can easily be realized, and the large degree of automatization allows for operation outside highly specialized laboratories for applications beyond basic research. Comparisons to existing high-accuracy optical clock systems enable a verification of the clock's stability and uncertainty budget at the low 10−17 level. During these tests, operation with 99.8% availability over more than 14 days has been achieved.

With a newly-developed generation of control electronics for diode lasers, modern concepts such as intuitive multi-touch operation or computersupported remote control are conquering laser laboratories worldwide. Simultaneously, the reduction of laser noise and drift has reached new records.

We present an overview from first external cavity diode lasers to current and future designs. Based on applications the requirements and realizations of tunable diode lasers are shown with respect to their importance to “Quantum Technology” initiatives.

We present a resonantly frequency-doubled tapered amplified semiconductor laser system emitting up to 2.6 W blue light at 400 nm. The output power is stable on both short and long timescales with 0.12% RMS relative intensity noise, and less than 0.15%/h relative power loss over 16 hours of free running continuous operation. Furthermore, the output power can be actively stabilized, and the alignment of the input beams of the tapered amplifier chip, the frequency doubling cavity and-in case of fiber output-the fiber can be optimized automatically using computer-controlled mirrors.

Single-frequency optical synthesizers (SFOS) provide an optical field with arbitrarily adjustable frequency and phase which is phase-coherently linked to a reference signal. Ideally, they combine the spectral resolution of narrow linewidth frequency stabilized lasers with the broad spectral coverage of frequency combs in a tunable fashion. In state-of-the-art SFOSs tuning across comb lines requires comb line order switching,1, 2 which imposes technical overhead with problems like forbidden frequency gaps or strong phase glitches. Conventional tunable lasers often tune over only tens of GHz before mode-hops occur. Here, we present a novel type of SFOSs, which relies on a serrodyne technique with conditional flyback,3 shifting the carrier frequency of the employed frequency comb without an intrusion into the comb generator. It utilizes a new continuously tunable diode laser that tunes mode-hop-free across the full gain spectrum of the integrated laser diode. We investigate the tuning behavior of two identical SFOSs that share a common reference, by comparing the phases of their output signals. Previously, we achieved phase-stable and cycle-slip free frequency tuning over 28.1 GHz with a maximum zero-to-peak phase deviation of 62 mrad4 when sharing a common comb generator. With the new continuously tunable lasers, the SFOSs tune synchronously across nearly 17800 comb lines (1 THz). The tuning range in this approach can be extended to the full bandwidth of the frequency comb and the 110 nm mode-hop-free tuning range of the diode laser.

We demonstrate a Doppler-free spectroscopic method that we test on 87 Rb and 85 Rb vapor. By using a magnetic field to induce a dichroism on the sample, we generate a dispersive signal with low background, which allows us to lock a diode laser even on small spectroscopic features. We elaborate the advantages of this simple and easy method by comparing it to other methods.

We report on the realization of a narrow-band continuous-wave laser source in the deep-ultraviolet. Via two consecutive second-harmonic processes starting from a near-infrared diode laser system, we demonstrate an output power of more than 15 mW at 193 nm. The setup is capable of mode hop-free frequency tuning over a range of 100 GHz und coarse tuning over more than 5 nm. We see direct applications of this laser source in the fields of semiconductor metrology and high-resolution spectroscopy in the deep-ultraviolet.

We describe a type of phase and frequency detector employing both an analog phase detector and a digital phase and frequency detector. The analog and digital detectors are mutually exclusive so that only one of them is active at any given time, resulting in a phase detector with both the broad capture range of digital circuits and the high speed and low noise of analog mixers. The detector has been used for phase locking the diode lasers generating the sequence of Raman pulses in an atom interferometer. The rms phase error of the phase lock is about 100 mrad in a 5 Hz–10 MHz bandwidth. The limit set on the interferometer phase resolution by the residual phase noise is 1.1 mrad. Since the digital circuitry is implemented with a programmable logic device the detector can be easily adapted to other experiments requiring frequency/phase stabilization of lasers sources.

Cr, different patterns can be generated. Possible applications using the inherent properties of atom lithography, e.g. the fabrication of photonic bandgap material, are discussed.

A continuous-wave deep-ultraviolet light source is demonstrated based on a grating-stabilized diode laser pump system and two consecutive nonlinear conversion stages. Using the crystal Potassium Fluoroberylloborate (KBBF), direct second-harmonic generation to 191 nm could be realized with an output power of up to 1.3 mW. The linewidth at this wavelength is estimated to be around 100 kHz. The emission can be tuned mode hop-free over 40 GHz. Our scheme can be easily extended to 193 nm or – given the availability of suitable fundamental sources – to wavelengths as small as 165 nm. These parameters make our light source an ideal tool for applications in deep-ultraviolet metrology and photoemission spectroscopy.

The use of ultra-precise optical clocks in space ("master clocks") will allow for a range of new applications in the fields of fundamental physics (tests of Einstein's theory of General Relativity, time and frequency metrology by means of the comparison of distant terrestrial clocks), geophysics (mapping of the gravitational potential of Earth), and astronomy (providing local oscillators for radio ranging and interferometry in space). Within the ELIPS-3 program of ESA, the "Space Optical Clocks" (SOC) project aims to install and to operate an optical lattice clock on the ISS towards the end of this decade, as a natural follow-on to the ACES mission, improving its performance by at least one order of magnitude. The payload is planned to include an optical lattice clock, as well as a frequency comb, a microwave link, and an optical link for comparisons of the ISS clock with ground clocks located in several countries and continents. Undertaking a necessary step towards optical clocks in space, the EU-FP7-SPACE-2010-1 project no. 263500 (SOC2) (2011-2015) aims at two "engineering confidence", accurate transportable lattice optical clock demonstrators having relative frequency instability below 1\times10^-15 at 1 s integration time and relative inaccuracy below 5\times10^-17. This goal performance is about 2 and 1 orders better in instability and inaccuracy, respectively, than today's best transportable clocks. The devices will be based on trapped neutral ytterbium and strontium atoms. One device will be a breadboard. The two systems will be validated in laboratory environments and their performance will be established by comparison with laboratory optical clocks and primary frequency standards. In this paper we present the project and the results achieved during the first year., Contribution to European Frequency and Time Forum 2012, Gothenburg, Sweden

We report ultra-stable locking of a commercially available extended cavity diode laser to a vibration-insensitive high finesse Fabry-Perot cavity. A servo bandwidth of 2 MHz is demonstrated. The absolute stability of the diode laser after locking is measured with a three-cornered-hat method. The resulting Allan deviation reaches a level of $2.95\times10^{-15}$ at 1 s, corresponding to only 0.93 Hz linewidth, even without vibration isolation of the reference cavity., 9 pages, 3 figures

Within the ELIPS program of ESA, the “Space Optical Clocks” (SOC) project aims to install and to operate an optical lattice clock on the ISS towards the end of this decade. In this project two accurate transportable lattice optical clock demonstrators having relative frequency instability below 1×10-15 at 1 s integration time and relative inaccuracy below 5×10-17 are under development. Crucial requirements are moderate volume, electrical power consumption and mass, and robustness. Furthermore, a modular concept is favourable.

We present a novel industrial-grade prototype version of a continuous-wave 193 nm laser system entirely based on solid state pump laser technology. Deep-ultraviolet emission is realized by frequency-quadrupling an amplified diode laser and up to 20 mW of optical power were generated using the nonlinear crystal KBBF. We demonstrate the lifetime of the laser system for different output power levels and environmental conditions. The high stability of our setup was proven in > 500 h measurements on a single spot, a crystal shifter multiplies the lifetime to match industrial requirements. This laser improves the relative intensity noise, brilliance, wall-plug efficiency and maintenance cost significantly. We discuss first lithographic experiments making use of this improvement in photon efficiency.

The Matter-Wave laser Interferometer Gravitation Antenna, MIGA, will be a hybrid instrument composed of a network of atom interferometers horizontally aligned and interrogated by the resonant field of an optical cavity. This detector will provide measurements of sub Hertz variations of the gravitational strain tensor. MIGA will bring new methods for geophysics for the characterization of spatial and temporal variations of the local gravity field and will also be a demonstrator for future low frequency Gravitational Wave (GW) detections. MIGA will enable a better understanding of the coupling at low frequency between these different signals. The detector will be installed underground in Rustrel (FR), at the "Laboratoire Souterrain Bas Bruit" (LSBB), a facility with exceptionally low environmental noise and located far away from major sources of anthropogenic disturbances. We give in this paper an overview of the operating mode and status of the instrument before detailing simulations of the gravitational background noise at the MIGA installation site., Proceedings of SPIE Photonics Europe conference, Brussels (Belgium), 3-7 April 2016