Andreas Wicht

• Humboldt-Universität zu Berlin

Frequency shift detection is crucial for advancing quantum, laser and metrology technologies. Here, we propose a compact design for detecting frequency shift in GaAs waveguides with mode-coupled Bragg gratings, which provides enhanced sensitivity. Our proposed architecture features a main ridge waveguide with a Bragg grating, flanked by two curved...

The INTENTAS project aims to develop an atomic sensor utilizing entangled Bose-Einstein condensates (BECs) in a microgravity environment. This key achievement is necessary to advance the capability for measurements that benefit from both entanglement-enhanced sensitivities and extended interrogation times. The project addresses significant challeng...

The design and optimization of optical components, such as Bragg gratings, are critical for applications in telecommunications, sensing, and photonic circuits. To overcome the limitations of traditional design methods that rely heavily on computationally intensive simulations and large datasets, we propose an integrated methodology that significant...

This study discusses the importance of accurately calculating the optical response of Bragg gratings and the challenges associated with the 3D finite-difference time-domain (FDTD) method for simulating large-scale structures. The Bragg grating section in monolithic extended cavity diode lasers is of substantial size, making 3D FDTD simulations comp...

The INTENTAS project aims to develop an atomic sensor utilizing entangled Bose-Einstein condensates (BECs) in a microgravity environment. This key achievement is necessary to advance the capability for measurements that benefit from both entanglement-enhanced sensitivities and extended interrogation times. The project addresses significant challeng...

(EN) The present invention relates to a device for arranging optical components in a thermally decoupled housing, in particular a low-stress suspended micro-optical bench that is thermally decoupled from a laser housing and is suitable for mobile and satellite-based applications, for example in quantum information technology and quantum sensor tech...

Acquiring a substantial number of data points for training accurate machine learning (ML) models is a big challenge in scientific fields where data collection is resource-intensive. Here, we propose a novel approach for constructing a minimal yet highly informative database for training ML models in complex multi-dimensional parameter spaces. To ac...

Precisely stabilizing laser frequency is crucial for advancing laser technology and unlocking the full potential of various quantum technologies. Here, we propose a compact device for stabilizing frequency of a semiconductor laser through mode coupling effects, which provides enhanced sensitivity. Our proposed architecture features a main ridge wav...

We present our latest hybrid micro-integrated fiber-coupled diode laser modules intended for use in an ⁸⁷ Rb atom interferometer in microgravity. The ECDL-MOPA concept allows high optical power emissions with a narrow linewidth.

Here we introduce efficient machine learning models trained on a 3D FDTD simulation-based database to predict Bragg grating characteristics from the main and the side lobes of reflectance spectra fitted by coupled mode theory.

We present the layout of a miniaturized laser distribution module as part of a ⁸⁸ Sr optical lattice clock. It consists of distributed Bragg reflector lasers (679 and 707 nm) combined with specifically developed, miniaturized electro-optical components.

This study focuses on accurately fit of the main and side lobes of reflectance obtained through precise 3D FDTD simulations using coupled-mode-theory. This approach based on surrogate modeling reduces the reliance on time-consuming FDTD simulations.

We present our narrow-linewidth micro-integrated diode laser modules that have already been successfully used for quantum technology applications on ground and in space, as well as our new generation of photonic modules.

We present and discuss measurement results of up to 4 mm long surface Bragg gratings in ridge-waveguides around 1064 nm for monolithic extended cavity diode lasers.

We report on the design and the construction of a sounding rocket payload capable of performing atom interferometry with Bose-Einstein condensates of $$^{41}$$ 41 K and $$^{87}$$ 87 Rb. The apparatus is designed to be launched in two consecutive missions with a VSB-30 sounding rocket and is qualified to withstand the expected vibrational loads of 1...

We report on the design and the construction of a sounding rocket payload capable of performing atom interferometry with Bose-Einstein condensates of $^{41}$K and $^{87}$Rb. The apparatus is designed to be launched in two consecutive missions with a VSB-30 sounding rocket and is qualified to withstand the expected vibrational loads of 1.8 g root-me...

Recent developments in quantum technology have resulted in a new generation of sensors for measuring inertial quantities, such as acceleration and rotation. These sensors can exhibit unprecedented sensitivity and accuracy when operated in space, where the free-fall interrogation time can be extended at will and where the environment noise is minima...

We determine Faraday rotations and measure the optical reflection and transmission from magneto-optical Cd 1− x Mn x Te crystals with various stoichiometric ratios. For wavelengths between 675 and 1025 nm, we derive Verdet constants, optical loss coefficients, and the complex indices of reflection that are relevant measures to find suitable stoichi...

We present the design of a novel Bragg grating based frequency reference with an expected frequency accuracy of 50MHz and a tuning range of more than 20GHz optimized for potassium-based quantum technology applications.

We present an experimental setup to investigate the sensitivity of ridge waveguide semiconductor optical amplifiers to optical feedback. We determine the amplification in forward and backward directions at 767nm at varying seed and feedback powers.

Improved laser facet passivation suppresses catastrophic optical mirror damage in 1064 nm and 767 nm ridge waveguide amplifiers. Accelerated lifetests reveal a reliability of more than 99% over the mission time of 10,000 h.

We present the mechanical simulations of a compact laser module intended for space-borne application on a small satellite. The device is designed to withstand the 10+ g rms random vibration without mechanical deterioration of the internal components.

AIP Adv., vol. 13, no. 1, pp. 015213, doi:10.1063/5.0130535 (2023) https://doi.org/10.1063/5.0130535

Abstract The authors report on design, fabrication, and electro‐optical characterization of single‐frequency diode lasers emitting around 696, 707, and 712 nm. This has been achieved by a variation of the periods of the 10th order surface Bragg gratings implemented on a single epitaxial wafer. Depending on the wavelength, the devices achieved an op...

The spectral linewidth of semiconductor lasers is a crucial performance parameter in a growing number of applications. A common method to improve the coherence of the laser relies on increasing the optical cavity length by an extended section without gain material. Here, this extended cavity diode laser (ECDL) concept is realized in a monolithic de...

We present distributed Bragg reflector lasers optimized for strontium-based quantum technology applications at 689.449 nm. The devices achieved optical output powers up to 88 mW, four times more than previously reported, and a spectral linewidth of 0 . 4MHz.

The phase noise caused by current fluctuations in single-pass semiconductor optical amplifiers is experimentally investigated. Using low-index quantum barrier designs in prototype devices is found to reduce phase noise by 18% compared to reference designs.

We present a monolithically integrated extended cavity diode laser at 778 nm with a 3 dB linewidth of 200 kHz @ 1 ms. This is the first successful demonstration of active layer removal in AlGaAs by a 2-step epitaxy manufacturing process.

We show wavelength-dependent measurements of Verdet constants and reflection/transmission values for various stoichiometric ratios of Cd 1 −x Mn x Te. From the data we derive absorption coefficients that help to design optical isolators for GaAs-based diode lasers.

Distributed Bragg Reflector semiconductor lasers are ideally suited for quantum technology applications due to their high efficiency, small footprint, and tunability in combination with the frequency stability provided by an integrated frequency selective element. Here we present the design, fabrication, and electro-optical characterization of DBR...

Microgravity eases several constraints limiting experiments with ultracold and condensed atoms on ground. It enables extended times of flight without suspension and eliminates the gravitational sag for trapped atoms. These advantages motivated numerous initiatives to adapt and operate experimental setups on microgravity platforms. We describe the d...

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 automat...

Future generations of global navigation satellite systems (GNSS) can benefit from optical technologies. Especially optical clocks could back-up or replace the currently used microwave clocks, having the potential to improve GNSS position determination enabled by their lower frequency instabilities. Furthermore, optical clock technologies - in combi...

Space-borne optical frequency references based on spectroscopy of atomic vapors may serve as an integral part of compact optical atomic clocks, which can advance global navigation systems or can be utilized for earth observation missions as part of laser systems for cold atom gradiometers. Nanosatellites offer low launch costs, multiple deployment...

Space-borne optical frequency references based on spectroscopy of atomic vapors may serve as an integral part of compact optical atomic clocks, which can advance global navigation systems, or can be utilized for earth observation missions as part of laser systems for cold atom gradiometers. Nanosatellites offer low launch-costs, multiple deployment...

The fabrication and characterisation details of novel distributed Bragg reflector (DBR) diode lasers emitting around 1064 nm are presented here. The AlGaAs epitaxial layer stack used here allows the removal of the active quantum wells in passive sections where no current is injected. The DBR lasers fabricated with a two‐step epitaxial approach with...

Bose-Einstein condensates (BECs) in free fall constitute a promising source for space-borne interferometry. Indeed, BECs enjoy a slowly expanding wave function, display a large spatial coherence and can be engineered and probed by optical techniques. Here we explore matter-wave fringes of multiple spinor components of a BEC released in free fall em...

Bose-Einstein condensates (BECs) in free fall constitute a promising source for space-borne matter-wave interferometry. Indeed, BECs enjoy a slowly expanding wave function, display a large spatial coherence and can be engineered and probed by optical techniques. On a sounding rocket, we explore matter-wave fringes of multiple spinor components of a...

Bose-Einstein condensates (BECs) in free fall constitute a promising source for space-borne matter-wave interferometry. Indeed, BECs enjoy a slowly expanding wave function [Anderson et. al. 1995, Becker et. al. 2018], display a large spatial coherence [Andrews et. al. 1997] and can be engineered and probed by optical techniques [Denschlag et. al. 2...

We present a novel approach for GaAs-based DBR diode lasers with an extended cavity. The developed chips exhibit a record small 3 dB linewidth of 25 kHz @ 1 ms at the wavelength of 1064 nm.

We present a hybrid microintegrated diode laser module developed for iodine spectroscopy on board a sounding rocket. The laser module is based on a master-oscillator-power-amplifier concept: an extended cavity diode laser serves as the master oscillator, and a ridge-waveguide semiconductor optical amplifier provides the power boost. The module’s fo...

A micro-integrated laser module has been developed for the deployment in a compact, transportable ¹⁷¹ Yb ⁺ optical clock. With this laser module, the clock laser system demonstrated a Modified Allan Deviation of less than 1.5×10 ⁻¹⁵ for 1 s ≤ 100 s when compared against a superior reference laser. © 2020 The Author(s)

A robust optical clock was developed, integrated into two mobile 19” rack assemblies and based on the 2S1/2-2D3/2 transition of a single 171Yb+ ion. The system design and a first complete evaluation will be discussed.

This paper presents a GaAs-diode laser-based hybrid integration approach for the realization of very complex, though compact and robust laser modules for QIST applications in the field and in space.

Microgravity eases several constraints limiting experiments with ultracold and condensed atoms on ground. It enables extended times of flight without suspension and eliminates the gravitational sag for trapped atoms. These advantages motivated numerous initiatives to adapt and operate experimental setups on microgravity platforms. We describe the d...

Within the OPUS collaboration, we develop optical frequency references based on spectroscopy of the 1S0→3P1 intercombination line of 88Sr at 689 nm in thermal and laser-cooled strontium beams for operation on sounding rockets. One main objective is to identify suitable experimental setups and core components for a compact and robust strontium beam...

We present a compact and robust distributed-feedback diode laser system architecture for ultracold atom experiments with and in a mobile setup operating at the ZARM drop tower in Bremen. Our system withstands DC accelerations of up to 43 g in operation with only minor adjustments over several drop campaigns. Micro-integrated master-oscillator–power...

Employing quantum sensors in field or in space implies demanding requirements on the used components and integration technologies. Within our work on compact atomic sensors, we develop miniaturized, ultra-stable optical setups for optical cooling and trapping of cold atomic gases on atom chips. Besides challenging demands on alignment precision and...

We build a self-contained optical absolute frequency reference at 1064 nm based on the rovibronic transition R(56)32-0 in molecular iodine and operate this instrument in space on a sounding rocket mission. The frequency reference uses a microintegrated extended cavity diode laser and a quasimonolithic spectroscopy module for modulation transfer spe...

One important building block for future integrated nanophotonic devices is the scalable on-chip interfacing of single photon emitters and quantum memories with single optical modes. Here we present the deterministic integration of a single solid-state qubit, the nitrogen-vacancy (NV) center, with a photonic platform consisting exclusively of SiO 2...

We present and compare theoretical and experimental results on the electro-optical performance of extended cavity diode lasers (ECDLs) that employ two ridge waveguide designs for the single-transverse mode GaAs laser diode chip. One facet of the laser diode chips serves as a partially reflective output coupler for the laser cavity. The other facet...

For studies of the European Space Agency ESA, Fraunhofer ILT develops and builds narrowband, power-stabilized fundamental mode fiber amplifiers especially for future space-based gravitational-wave detectors, e.g. LISA, and for Earth gravity field missions. In this paper, we present the status of our ongoing work, based on a highly stable fiber ampl...

As part of the phase 0/A of the QUEEN mission, we evaluated our payload and satellite platform heritage and studied feasible mission scenarios for demonstrating optical frequency references aboard small satellites. We propose an optical vapor-cell frequency reference payload based on the 5S1/2 → 5D5/2 two-photon transition in 85Rb with low size, we...

Thermally grown silica is one of the most desirable materials for the realization of optical waveguides and whispering-gallery mode micro-resonators due to the ultra-low propagation loss and broad transparency window from UV to mid-IR. Here we present the design, fabrication, and characterization of a high-Q ring-resonator device with a monolithica...

One important building block for future integrated nanophotonic devices is the scalable on-chip interfacing of single photon emitters and quantum memories with single optical modes. Here we present the deterministic integration of a single solid-state qubit, the nitrogen-vacancy (NV) center, with a photonic platform consisting exclusively of SiO2 g...

Owing to the low-gravity conditions in space, space-borne laboratories enable experiments with extended free-fall times. Because Bose–Einstein condensates have an extremely low expansion energy, space-borne atom interferometers based on Bose–Einstein condensation have the potential to have much greater sensitivity to inertial forces than do similar...

BECCAL (Bose-Einstein-Condensate - Cold Atom Laboratory) is an experiment designed to be housed on the International Space Station (ISS) within a bilateral collaboration between DLR and NASA. The payload's design and operation are based on the previous quantum experiments under microgravity, QUANTUS (drop tower), MAIUS (sounding rocket), and CAL (N...

As part of the phase 0/A of the QUEEN mission, we evaluated our payload and satellite platform heritage and studied feasible mission scenarios for demonstrating optical frequency references onboard small satellites. We propose an optical vapor-cell frequency reference payload based on the 5S1/2  5D5/2 two-photon transition in 85 Rb with low size,...

The influence of the front facet reflectivity on the spectral linewidth of high power DFB (distributed feedback) diode lasers emitting at 780 nm has been investigated theoretically and experimentally. Characterization of lasers at various front facet reflections showed substantial reduction of the linewidth. This behavior is in reasonable agreement...

Space offers virtually unlimited free-fall in gravity. Bose-Einstein condensation (BEC) enables ineffable low kinetic energies corresponding to pico- or even femtokelvins. The combination of both features makes atom interferometers with unprecedented sensitivity for inertial forces possible and opens a new era for quantum gas experiments. On Januar...

Space offers virtually unlimited free-fall in gravity. Bose-Einstein condensation (BEC) enables ineffable low kinetic energies corresponding to pico - or even femtokelvins. The combination of both features makes atom interferometers with unprecedented sensitivity for inertial forces possible and opens a new era for quantum gas experiments. On Janua...

Efficient single photon sources effectively coupled to a single optical mode pose a crucial building block for future applications in quantum information science [1]. So far quantum optics experiments with single photon emitters, e.g. nitrogen-vacancy (NV) centers in diamond are limited to large experimental setups with sophisticated detection syst...

We build a self-contained optical absolute frequency reference at 1064 nm based on the rovibronic transition R(56)32-0 in molecular iodine and operate this instrument in space on a sounding rocket mission. The frequency reference uses a microintegrated extended cavity diode laser and a quasimonolithic spectroscopy module for modulation transfer spe...

Within the European Space Agency (ESA) activity “Gravitational Wave Observatory Metrology Laser” we designed a laser head to fulfill the LISA laser requirements using a non-NPRO seed laser technology: an external cavity diode laser (ECDL) with resonant optical feedback from an external cavity as master oscillator for further linewidth narrowing. Fu...

We present a compact, mode-locked diode laser system designed to emit a frequency comb in the wavelength range around 780 nm. We compare the mode-locking performance of symmetric and asymmetric double quantum well ridge-waveguide diode laser chips in an extended-cavity diode laser configuration. By reverse biasing a short section of the diode laser...

Nowadays, cold atom-based quantum sensors such as atom interferometers are leaving the optical labs [1,2], thus allowing fundamental physics to be tested in space. The use of different quantum objects such as Potassium (K) and Rubidium (Rb) ultra-cold quantum gases enables tests of the Universality of Free Fall (UFF) [1–4]. While narrow linewidth l...

We have developed, assembled, and flight-proven a stable, compact, and autonomous extended-cavity diode laser (ECDL) system designed for atomic physics experiments in space. To that end, two microintegrated ECDLs at 766.7 nm were frequency stabilized during a sounding rocket flight by means of frequency modulation spectroscopy of and offset locking...

We present the technical realization of a compact system for performing experiments with cold $^{87}{\text{Rb}}$ and $^{39}{\text{K}}$ atoms in microgravity in the future. The whole system fits into a capsule to be used in the drop tower Bremen. One of the advantages of a microgravity environment is long time evolution of atomic clouds which yields...

A flexible method to measure the modulation efficiency and residual amplitude modulation, including non-linearities, of phase modulators is presented. The method is based on demodulation of the modulated optical field in the optical domain by means of a heterodyne interferometer and subsequent analysis of the I&Q quadrature components of the corres...

We present a micro-integrated laser module consisting of an extended cavity diode laser and an optical amplifier. The fiber-coupled laser module emits 570 mW from a single mode, polarization maintaining fiber at 1064 nm with a FWHM linewidth of 26 kHz (1 ms).

We present a compact absolute optical frequency reference based on hyperfine transitions in molecular iodine for application on a sounding rocket mission. It is based on a micro-integrated extended cavity diode laser at 1064 nm with integrated optical amplifier, fiber pigtailed second harmonic generation wave-guide modules, and a quasi-monolithic s...

Precision time references in space are of major importance to satellite-based fundamental science, global satellite navigation, earth observation, and satellite formation flying. Here we report on the operation of a compact, rugged, and automated optical frequency comb setup on a sounding rocket in space under microgravity. The experiment compared...

We present the technical realization of a compact system for performing experiments with cold $^{87}{\text{Rb}}$ and $^{39}{\text{K}}$ atoms in microgravity in the future. The whole system fits into a capsule to be used in the drop tower Bremen. One of the advantages of a microgravity environment is long time evolution of atomic clouds which yields...

We have developed, assembled, and flight-proven a stable, compact, and autonomous extended cavity diode laser (ECDL) system designed for atomic physics experiments in space. To that end, two micro-integrated ECDLs at 766.7 nm were frequency stabilized during a sounding rocket flight by means of frequency modulation spectroscopy (FMS) of 39^K and of...

We present a diode laser system optimized for laser cooling and atom interferometry with ultra-cold rubidium atoms aboard sounding rockets as an important milestone towards space-borne quantum sensors. Design, assembly and qualification of the system, combing micro-integrated distributed feedback (DFB) diode laser modules and free space optical ben...