Jechow A.,University of Potsdam |
Menzel R.,University of Potsdam |
Paschke K.,Ferdinand - Braun - Institute |
Erbert G.,Ferdinand - Braun - Institute
Laser and Photonics Reviews | Year: 2010
A review about second harmonic generation using dge emitting diode lasers and nonlinear crystals to obtain laser adiation in the blue-green spectral range is presented. Therefore, ump laser radiation with high brightness and narrow andwidth is necessary. Thus, this review gives an overview of he advances made with distributed feedback and Bragg reflector asers, tapered lasers and amplifiers as well as external cavity iode lasers and master oscillator power amplifier schemes to achieve high brilliance emission. Since periodically poled materials have enabled high second harmonic conversion efficiencies with low and moderate pump powers, the review is focused on frequency doubling using those materials. The most commonly used materials, their properties and limitations are discussed briefly. Single pass and resonant SHG setups with waveguide and bulk nonlinear crystals are discussed and an emphasis on building compact and integrated devices is made. © 2010 by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Klopp P.,Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy |
Griebner U.,Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy |
Zorn M.,Ferdinand - Braun - Institute |
Zorn M.,Jenoptik Diode Laboratory GmbH |
Weyers M.,Ferdinand - Braun - Institute
Applied Physics Letters | Year: 2011
A semiconductor disk laser based on an InGaAs/AlGaAs quantum-well gain medium was mode-locked by a fast semiconductor saturable absorber mirror. By high-order harmonic mode-locking a 92 GHz pulse train was obtained with a pulse duration of <200 fs. In order to achieve fundamental mode-locking, too strong saturation of the semiconductor elements had to be avoided. In a single-pulse regime, pulses shorter than 110 fs were generated at a wavelength of 1030 nm. © 2011 American Institute of Physics.
Bathich K.,TU Berlin |
Boeck G.,TU Berlin |
Boeck G.,Ferdinand - Braun - Institute
IEEE MTT-S International Microwave Symposium Digest | Year: 2012
This paper presents the design of a wideband harmonically-tuned Doherty amplifier. The frequency-dependent back-off efficiency degradation was minimized by compensating the effect of the frequency-sensitive impedance inverters over the design band. Suitable choice of device size ratio as well as harmonic load tuning at back-off and maximum power operations were also considered, resulting in superior performance over the targeted design band. The maximum output power ranged from 48.2 dBm to 49.6 dBm. 6 dB back-off efficiencies of η6dB53 % (power-added efficiency PAE50 %) were measured over L.7-2.25 GHz (28 % bandwidth). When linearized using digital pre-distortion (DPD), the Doherty amplifier had adjacent-channel leakage ratio (ACLR) of 43 dBc for a long-term evolution (LTE) signal at L.85 GHz (η=50 %) and 44 dBc for a wideband code-division multiple access (W-CDMA) signal at 2.11 GHz (η=41 %), at average output power of 4L.0 dBm and 40.5 dBm, respectively. © 2012 IEEE.
Guther R.,Ferdinand - Braun - Institute
Optics Letters | Year: 2012
The recently calculated high diffraction efficiencies for TE- and TM-polarized light (perfect blaze) for echelette gratings are explained by four-wave interference, which is formed as a double periodical pattern in the cross section of the grating plane. The blazed grating profile should match this interference pattern for a single reference light wavelength. The recently published data are the special case of a general design. The prognoses of the model are connected with large grating constants in comparison with the light wavelength, where short grating constants need comparison with numerical methods. © 2012 Optical Society of America.
Wentzel A.,Ferdinand - Braun - Institute |
Meliani C.,Ferdinand - Braun - Institute |
Heinrich W.,Ferdinand - Braun - Institute
IEEE MTT-S International Microwave Symposium Digest | Year: 2010
This paper reports recent results on a current-mode class-S power amplifier for the 450 MHz band, based on GaNHEMT MMICs. We achieve a peak output power of 8.7 W for a single tone at 420 MHz, encoded in standard band-pass deltasigma modulation with 1.68 Gbps sampling frequency. The respective efficiency is 34%. We find that these values strongly vary with coding efficiency of the modulation and reach 19 W with 59% for square-wave excitation. In order to clarify the potential of the PA in more detail, the S-class characteristics at power back-off and with varying oversampling ratio are presented as well. © 2010 IEEE.
Rumiantsev A.,TU Brandenburg |
Doerner R.,Ferdinand - Braun - Institute
IEEE Microwave Magazine | Year: 2013
Today, radio-frequency (RF) wafer probes play an important role in almost every step of the RF products lifecycle: from technology development, model parameter extraction, design verification, and debug to small-scale and final production test. By using RF probes, it became possible to measure true characteristics of the RF components at the wafer level. One of the earliest measurement results obtained using RF probes were presented in, demonstrating usable device data up to 4 GHz. The probes used in this experiment were very different from today's tools. While it was possible to remove the impact of relatively large series inductance of a contact wire tip by the calibration procedure, the authors of observed large changes in the radiation impedance of the wire tip when the wafer chuck was moved.
Wurfl J.,Ferdinand - Braun - Institute
2014 Asia-Pacific Microwave Conference Proceedings, APMC 2014 | Year: 2014
An overview on European GaN technologies towards high power microwave and high voltage power switching applications is presented. It contains a survey on the most important technological approaches, device performance data and reliability achievements. A special emphasis is devoted to the GaN technologies available at Ferdinand-Braun-Institut (FBH), Berlin. Copyright 2014 IEICE.
Wenzel H.,Ferdinand - Braun - Institute
IEEE Journal on Selected Topics in Quantum Electronics | Year: 2013
The aim of this paper is to review some of the models and solution techniques used in the simulation of high-power semiconductor lasers and to address open questions. We discuss some of the peculiarities in the description of the optical field of wide-aperture lasers. As an example, the role of the substrate as a competing waveguide in GaAs-based lasers is studied. The governing equations for the investigation of modal instabilities and filamentation effects are presented and the impact of the thermal-lensing effect on the spatiotemporal behavior of the optical field is demonstrated. We reveal the factors that limit the output power at very high injection currents based on a numerical solution of the thermodynamic based drift-diffusion equations and elucidate the role of longitudinal spatial hole burning. © 1995-2012 IEEE.
Sumpf B.,Ferdinand - Braun - Institute
Proceedings - 2016 International Conference Laser Optics, LO 2016 | Year: 2016
Wavelength stabilized high-power diode lasers are requested light sources in the field of laser based sensor systems. They are used as pump lasers for non-linear frequency conversion, e.g. second harmonic generation, to pump solid state fs-laser devices applied for diagnostic purposes in life sciences and they are applied directly as light sources for absorption or Raman spectroscopy. This paper presents recent developments concerning distributed Bragg reflector (DBR) ridge waveguide (RW) diode lasers for vibrational spectroscopy and high brightness DBR-Tapered lasers for non-linear optics. The manufacturing and the electro-optical, spectral, and beam parameters of these devices will be presented together with a compact handheld Raman probe using an implemented dual-wavelength DBR-RW diode laser for Shifted Excitation Raman Difference Spectroscopy (SERDS). © 2016 IEEE.
Netzel C.,Ferdinand - Braun - Institute |
Knauer A.,Ferdinand - Braun - Institute |
Weyers M.,Ferdinand - Braun - Institute
Applied Physics Letters | Year: 2012
We analyzed emission intensity, quantum efficiency, and emitted light polarization of c-plane AlGaN and AlInGaN layers (λ=320-350nm) by temperature dependent photoluminescence. Low indium content in AlInGaN structures causes a significant intensity increase by change of the polarization of the emitted light. Polarization changes from E⊥ c to E∥c with increasing aluminum content. It switches back to E ⊥ c with the incorporation of indium. The polarization degree decreases with temperature. This temperature dependence can corrupt internal quantum efficiency determination by temperature dependent photoluminescence. © 2012 American Institute of Physics.