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.
Photonic Integrated Circuits (PIC) will change the fundamental paradigms for the design of multi-color laser engines for life sciences. Exemplified with flow cytometry (FCM), integrated optical technology for visible wavelengths will be shown to open a new spectrum of possibilities to control flow cell illumination patterns, such as the number of output spots, the spot size, and even complex patterns generated by interferometry. Integration of additional optical functions such as variable optical attenuation, wavelength division multiplexing or fast shutters adds value to the PIC. TOPTICA is demonstrating integration of PICs in present Multi-color Laser Engine (MLE) architectures. Multiple wavelengths (405nm, 488nm, 561nm, 640nm) are coupled free space into the chip, leveraging its beam steering COOLAC (Constant Optical Output Level Auto Calibration) technology for automatic realignment, thus overcoming the need of fiber input delivery. Once in the waveguide, the light can be redirected and shaped to a desired output pattern and pitch, reducing the need of discrete optical components. In this work, we will discuss the implementation of various building blocks in PIC technology for MLEs and analyze the advantages over current macroscopic counterparts.
This work reports on a compact single-mode diode laser emitting at 633 nm based on an AlGaAs/AlGaInP structure with an integrated DBR surface grating. The micro-fabricated diode laser package includes optics for beam shaping, optical isolation and single-mode fiber coupling. The miniaturized optical isolator is based on cadmium manganese telluride, which provides a large Verdet constant and thus enables the realization of a compact Faraday rotator in the visible spectral range. We discuss the performance and the technological challenges for this approach. Furthermore, we present prospects towards the integration of atomic reference cells into compact laser systems. This would enable the realization of absolute frequency-stabilized diode lasers that could be used in quantum technology devices.
Several holographic and interferometric applications would benefit significantly from a diode laser based coherent light source near 633 nm. For this purpose a laser diode based on an AlGaAs/AlGaInP structure for emission in the red spectral range was developed. The laser chip features a ridge waveguide and a DBR surface grating at the rear side with a peak reflectivity at 633 nm. The laser was mounted in a butterfly-style package for temperature stabilization. The beam emitted by the laser diode was shaped with two cylindrical micro-lenses and passed through a custom-built CdMnTebased micro-optical isolator. The beam behind the isolator was coupled into a polarization maintaining (PM) single-mode fiber using an aspherical lens. The optical output power of the fiber was about 1.7 mW at 100 mA.
The performance of large ground-based optical telescopes is limited due to wavefront distortions induced by atmospheric turbulence. Adaptive optics systems using natural guide stars with sufficient brightness provide a practical way for correcting the wavefront errors by means of deformable mirrors. Unfortunately, the sky coverage of bright stars is poor and therefore the concept of laser guide stars was invented, creating an artificial star by exciting resonance fluorescence from the mesospheric sodium layer about 90 km above the earth’s surface. Until now, mainly dye lasers or sumfrequency mixing of solid state lasers were used to generate laser guide stars. However, these kinds of lasers require a stationary laser clean room for operation and are extremely demanding in maintenance. Under a development contract with the European Southern Observatory (ESO) and W. M. Keck Observatory (WMKO), TOPTICA Photonics AG and its partner MPB Communications have finalized the development of a next-generation sodium guide star laser system which is available now as a commercial off-the-shelf product. The laser is based on a narrow-band diode laser, Raman fiber amplifier (RFA) technology and resonant second-harmonic generation (SHG), thus highly reliable and simple to operate and maintain. It emits > 22 W of narrow-linewidth (≈ 5 MHz) continuous-wave radiation at sodium resonance and includes a re-pumping scheme for boosting sodium return flux. Due to the SHG resonator acting as spatial mode filter and polarizer, the output is diffraction-limited with RMS wavefront error < λ/25. Apart from this unique optical design, a major effort has been dedicated to integrating all optical components into a ruggedized system, providing a maximum of convenience and reliability for telescope operators. The new remote-pumping architecture allows for a large spatial separation between the main part of the laser and the compact laser head. Together with a cooling-water flow of less than 5 l/min and an overall power consumption of < 700 W, the system offers a maximum of flexibility with minimal infrastructure demands on site. Each system is built in a modular way, based on the concept of line-replaceable units (LRU). A comprehensive system software, as well as an intuitive service GUI, allow for remote control and error tracking down to at least the LRU level. In case of a failure, any LRU can be easily replaced. With these fiber-based guide star lasers, TOPTICA for the first time offers a fully engineered, off-the-shelf guide star laser system for groundbased optical telescopes providing convenient, turn-key operation in remote and harsh locations. Reliability and flexibility will be beneficial in particular for advanced satellite and space debris tracking as well as LIDAR applications.
Large telescopes equipped with adaptive optics require high power 589-nm continuous-wave sources with emission linewidths of ~5 MHz. These guide-star lasers should be highly reliable and simple to operate and maintain for many years at the top of a mountain facility. After delivery of the first 20-W systems to our lead customer ESO, TOPTICA and MPBC have begun series production of next-generation sodium guide-star lasers. The chosen approach is based on ESO’s patented narrow-band Raman fiber amplifier (RFA) technology . A master oscillator signal from a TOPTICA 50-mW, 1178-nm diode laser, with stabilized emission frequency and linewidth of ~ 1 MHz, is amplified in an MPBC polarization-maintaining (PM) RFA pumped by a high-power 1120-nm PM fiber laser. With efficient stimulated Brillouin scattering suppression, an unprecedented 40 W of narrow-band RFA output has been obtained. This is spatially mode-matched into a patented resonant-cavity frequency doubler providing also the repumper light . With a diffraction-limited output beam and doubling efficiencies < 80%, all ESO design goals have been easily fulfilled. Together with a wall-plug efficiency of < 3%, including all system controls, and a cooling liquid flow of only 5 l/min, the modular, turn-key, maintenance-free and compact system design allows a direct integration with a launch telescope. With these fiber-based guide star lasers, TOPTICA for the first time offers a fully engineered, off-the-shelf guide star laser system for ground-based optical telescopes. Here we present a comparison of test results of the first batch of laser systems, demonstrating the reproducibility of excellent optical characteristics.
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.
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 frequency-doubled radiation of an Erbium-doped fiber laser is used for supercontinuum generation in a small-core
microstructured fiber with two zero-dispersion wavelengths. Average powers up to 49 mW are launched
into the highly nonlinear photonic-crystal fiber. The generated supercontinuum shows a short-wavelength peak
centered around 670 nm and a long-wavelength peak centered around 1100 nm. More than 35 mW is contained
in the short-wavelength peak. We use the anomalous dispersion of a SF10 prism compressor to compress the
short-wavelength peak of the spectrum. The compressed pulse has a central wavelength of 670 nm and a duration
of 27 fs.
The different flavors of today's and future multilayer transmission networks are analyzed highlighting the main infrastructure, capital expenditure (CAPEX) and operational expenditure (OPEX) contributions to total cost of ownership (TCO). Depending on different carrier requirements, critical parameters and general design rules for optimum overall cost positions are discussed. To illustrate and evaluate the impact of given boundary conditions, some case studies will be presented where new technologies lead to significant OPEX/CAPEX savings.