Günther Tränkle

Ferdinand-Braun-Institut | FBH

Y-branch distributed Bragg reflector (DBR) diode lasers with a stable narrowband emission in simultaneous dual-wavelength operation with spectral distances below 3.2 nm are presented. The Y-branch laser consists of two laser branches with different DBR gratings serving as wavelength-selective rear-side mirrors. Therefore, two emission wavelengths w...

We present a high-power ridge waveguide distributed feedback (DFB) laser with a high-reflective coating and a phase shift section at the rear facet. The phase shift section is realized by means of a micro heater that is placed parallel to the ridge waveguide and the uniform grating. This type of heater section is easy to integrate into existing las...

Local temperature non-uniformity is a critical limit to power in large-area semiconductor lasers, playing a larger role than the conversion efficiency and temperature sensitivity in the most efficient modern devices. For the specific case of kilowatt-level edge-emitting diode laser bars, we demonstrate that laterally re-distributing current locally...

Widespread commercial adoption of telecom‐band quantum key distribution (QKD) will require fully integrated, room‐temperature transmitters. Implementing highly efficient spontaneous parametric down‐conversion (SPDC) on a platform that offers co‐integration of the pump laser has been an outstanding challenge. Here, using such a platform based on AlG...

We present a laser module with dimensions of ${76} \times {43} \times {15}\;{{\rm mm}^3}$ 76 × 43 × 15 m m 3 that for the first time to our knowledge realizes a coherent beam combination in such a compact device, using two tapered amplifiers seeded by a distributed Bragg reflector ridge waveguide laser diode operating at 761 nm in a single longitud...

An experimental study of straight and bent distributed Bragg reflector (DBR) ridge waveguide (RW) lasers and Fabry-Pérot RW lasers emitting at 785 nm is presented. To determine the losses introduced by the bent waveguides within DBR-RW lasers, different laser designs were manufactured and characterized. The bent waveguides investigated here within...

The rapid advancement of $$^{9}\hbox {Be}^{+}$$ 9 Be + ion-based quantum computing is creating a high demand for scalable and specialized laser sources. For this purpose, laser radiation at 313 nm is necessary which is generated by frequency doubling of 626 nm laser emission. Laser sources in this spectral region lack simplicity and need to be mini...

Current progress in the scaling of continuous wave optical output power and conversion efficiency of broad-area GaAs-based edge emitters, broad-area lasers (BALs), operating in the 900…1000 nm wavelength range is presented. Device research and engineering efforts have ensured that BALs remain the most efficient of all light sources, so that in the...

Distributed feedback (DFB) broad area (BA) lasers with multiple epitaxially stacked active regions and tunnel junctions designed for emission around 900 nm are investigated. DFB BA lasers with a cavity length of 1 mm and different stripe widths are compared in terms of their electro-optical performance and beam quality. The laser with a 200 µm stri...

Spatial-hole-burning as a limit to the continuous-wave (CW) output power of GaAs-based diode lasers is experimentally studied. For 90 μm stripe lasers with 6 mm resonator length and 0.8% front facet reflectivity, spontaneous emission (SE) intensity data show that the carrier density in the device center rises rapidly at the rear facet with bias and...

Lasers with emission wavelengths in the near-ultraviolet (UV) spectral range have been used in many applications across various fields, and the demand for these lasers has been on the rise. For example, in medicine, near-UV light has been used for fluorophore excitation. Although laser diodes emitting in this region exist, single longitudinal mode...

Abstract In this letter, the authors present a monolithic edge emitting diode laser intended as a potential key component for the generation of terahertz radiation in a compact time‐domain spectroscopy system. The 6 mm long multi‐section InGaAsP double quantum well (DQW) laser, featured with a 3.6 mm long tapered (TP) gain section, operates at a wa...

We report unprecedentedly low second harmonic band propagation losses in highly nonlinear AlGaAs-on-insulator waveguides pumped in the telecom L-band. These rafindings pave the way towards pa metric nonlinearities at single photon-level.

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 report on the first observation of spontaneous parametric down-conversion and a highly efficient second harmonic generation with η shg ≈ 420 %/W/mm ² in AlGaAs- on-insulator waveguides operated at telecom wavelengths.

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...

The presence of a thermally annealed metallization layer on top of a GaAs slab waveguide proofed to be of strong impact on the optical device behavior. Induced by the stress on the chip the elasto-optical effect imprinted a strong variation on the refractive index that led to anti-guiding and guiding effects. In order to enable precise prediction o...

An experimental comparison between individual and common wavelength-operation of a Y-branch distributed Bragg reflector (DBR) ridge waveguide (RW) laser at 785 nm with an electrically adjustable spectral distance is presented. The dual-wavelength Y-branch laser combines two laser cavities via a Y-section to a common output section. DBR gratings wit...

An all-diode laser-based master oscillator power amplifier (MOPA) configuration for the generation of ns-pulses with high peak power, stable wavelength and small spectral line width is presented. The MOPA emits alternating at two wavelengths in the spectral range between 964 nm and 968 nm, suitable for the detection of water vapor by absorption spe...

Wavelength stabilized distributed Bragg reflector (DBR) tapered diode lasers at 783 nm will be presented. The devices are based on GaAsP single quantum wells embedded in a large optical cavity leading to a vertical far field angle of about 29° (full width at half maximum). The 3-inch (7.62 cm) wafers are grown using metalorganic vapor phase epitaxy...

Lasing emission at multiple wavelengths can be used in different sensing applications and in optical telecommunication. In this work, we report a six-wavelength distributed Bragg reflector (DBR) laser, emitting around 976 nm with six ridge waveguide (RW) structures, where individual DBR gratings are combined into a common front section. These six e...

Laser diode minibars for QCW pumping Nd:YAG at 63 W were developed for the satellite MERLIN and subjected to accelerated life test. Evaluating 320 single emitters indicates a reliability of 99.99% during the mission lifetime.

Wide field Raman imaging using the integral field spectroscopy approach was used as a fast, one shot imaging method for the simultaneous collection of all spectra composing a Raman image. For the suppression of autofluorescence and background signals such as room light, shifted excitation Raman difference spectroscopy (SERDS) was applied to remove...

Wide field Raman imaging using the integral field spectroscopy approach was used as a fast, one shot imaging method for the simultaneous collection of all spectra composing a Raman image. For the suppression of autofluorescence and background signals such as room light, shifted excitation Raman difference spectroscopy (SERDS) was applied to remove...

In this work, the influence of strong optical feedback on the emission behavior of distributed Bragg-reflector ridge waveguide diode lasers emitting at 1120 nm with different cavity lengths and facet reflectivities is investigated. Based on measurements of the optical output power, central emission wavelength, and spectral emission width, the diffe...

In this paper, the properties of Pd-based p-contacts on GaN-based laser diodes are discussed. Pd is often the metal of choice for ohmic contacts on p-GaN. However, for Pd/p-GaN ohmic contacts, nanovoids observed at the metal/semiconductor interface can have a negative impact on reliability and also reproducibility. The authors present a thorough an...

Recent progress in the development of deep ultraviolet lasers is reviewed as well as challenges for the heterostructure design and epitaxial growth for AlGaN-based laser diodes are discussed. The growth of AlN on sapphire and AlGaN heterostructures is reviewed and its impact on the performance characteristics of lasers in the UVC spectral range is...

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...

Background: Various cutaneous toxicities under chemotherapy indicate a local effect of chemotherapy by secretion after systemic application. Here, changes in the fluorescence and Raman spectral properties of the stratum corneum subsequent to intravenous chemotherapy were assessed. Methods: Twenty healthy subjects and 20 cancer patients undergoin...

Carbon‐doping of GaN layers with thickness in the mm‐range is performed by hydride vapor phase epitaxy. Characterization by optical and electrical measurements reveals semi‐insulating behavior with a maximum of specific resistivity of 2 × 1010 Ω cm at room temperature found for a carbon concentration of 8.8 × 1018 cm−3. For higher carbon levels up...

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...

Compact laser sources emitting at multiple wavelengths from a single aperture are interesting in a multiple of applications. In this work, we characterize and compare two concepts of four-arm monolithic distributed Bragg reflector (DBR) ridge waveguide (RW) diode lasers emitting at four different wavelengths around 970 nm. The first concept has a s...

We present a new theoretical design for diode lasers which should be capable of generating sub-100-ps pulses with pulse energies of more than 10 nJ per 100-μm-contact width by active Q-switching. We show that the carrier-induced reduction of the refractive index in the active layer, i.e. the vertical anti-index guiding effect, results in a dependen...

Carbon doped GaN crystals grown by hydride vapor phase epitaxy have been investigated using mid-infrared and near-ultraviolet absorption spectroscopy. Two local vibrational modes (LVMs) at 1679 cm−1 and 1718 cm−1 as well as an absorption shoulder in front of the band edge absorption of GaN are discovered, all of which increase in intensity with the...

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...

A system for shifted excitation resonance Raman spectroscopy (SERRDS) suitable for the application in medical practice for the in vivo detection of carotenoids in human skin is presented. This system comprises a miniaturized (150 mm × 27 mm × 12 mm) handheld probe and a wavelength-tunable diode laser-based 488 nm SHG light source. The diode laser p...

Aluminum nitride growth via hydride vapor phase epitaxy has been investigated with respect to impurity uptake. The precursor aluminum chloride was identified to react with quartz glass and provide silicon into the reactor atmosphere and subsequently into grown AlN layers. Reactor parts made of quartz were consecutively replaced by carbon glass part...

Tunable high-power diode lasers are key components in various established and emerging applications. In this work, we present a compact hybrid master oscillator power amplifier (MOPA) laser system. The system utilizes a tunable GaAs-based sampled-grating (SG) distributed Bragg reflector (DBR) laser as the master oscillator (MO), which emits around...

Passive S-bend waveguides have been thoroughly studied in the past, however active S-bend structures such as those in Y-branch distributed Bragg reflector (DBR) ridge waveguide (RW) lasers have been paid little attention. In this work, different S-bend based Y-branch DBR lasers emitting at 976 nm are developed, and their electro-optical, spectral a...

A high power widely tunable master oscillator power amplifier (MOPA) laser system will be presented, emitting between 962.0 nm - 985.5 nm, with an output power in the watt range.

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...

In this paper, we present rapid and adjustable shifted excitation Raman difference spectroscopy (SERDS). A dual‐wavelength diode laser emitting at 785 nm is used as the excitation light source. Two laser resonators are realized in a single chip, and two distributed Bragg reflector gratings provide two excitation lines at 785 nm. For each laser line...

Asynchronous optical sampling terahertz time-domain spectroscopy using semiconductor laser-based ultra-short pulse sources is demonstrated. A pair of hybridly mode-locked edge-emitting external cavity lasers operating at a wavelength of 830 nm is used. Terahertz traces with spectral components over a range of 250 GHz are achieved.

In this work, a widely tunable hybrid master oscillator power amplifier (MOPA) diode laser with 6.2 W of output power at 971.8 nm will be presented. The MO is a DBR laser, with a micro heater embedded on top of the DBR grating for wavelength tunability. The emitted light of the MO is collimated and coupled into a tapered amplifier using micro cylin...