We report on the use of micro-LED arrays, consisting a matrix interconnected micrometer-size light-emitting diodes (LEDs), to ensure uniform current injection, reduced series resistance, and improved heat extraction in LEDs emitting ultraviolet wavelength region. With help experiments simulations, we show that, both 380- 300- 325-nm LEDs, greater than twofold decrease thermal resistance device, as compared with conventional large area contact, is possible arrays. The was found linearly size...

The degradation of the electrical and optical properties (InAlGa)N-based multiple quantum well light emitting diodes (LEDs) near 308 nm under different stress conditions has been studied. LEDs with emission areas were operated at room temperature constant current densities 75 A/cm2, 150 225 A/cm2. In addition, heat sink was varied between 15 °C 80 °C. Two main modes for reduction power found, which dominate times operation: (1) Within first 100 h, a fast drop is observed scaling...

The degradation behavior of ultraviolet-B light emitting diodes (UV-B LEDs) near 310 nm has been investigated and a method to localize the effects is presented. Measurements electro-optical characteristics UV-B LEDs, during 200 h constant-current study, showed an initial fast decrease in optical power accompanied by drive voltage increase capacitance. Furthermore, using specially designed contact geometry, it was possible separate electrical properties p-layers p-contacts from active region...

The electroluminescence of UVB light-emitting diodes emitting at 310 nm before and after 1000 h operation is studied in the temperature range from 20 to 340 K. Before operation, external quantum efficiency (EQE) 10 mA gradually increases with decreasing 0.8% K 1.8% 150 then levels off. This trend attributed a reduction non-radiative recombination finally domination radiative low temperatures. After EQE has dropped 0.45% maximum 1.4% 80 K, followed by drop for temperatures below These...

We present a broadband flip-chip approach for the hetero-integration of indium phosphide based chiplets on BiCMOS carrier. To accommodate limited temperature budget, process temperatures are kept below 200°C in order to not degrade device performance. Using soldering together with pillar-based instead common bump array technique ensures good scalability, repeatability and flexibility terms complex transitions. The RF performance this transitions was evaluated using standard 50Ω microstrip...

The output power of modern 975 nm GaAs-based broad area diode lasers is limited by increasing carrier and photon losses at high bias. We use experiment one-dimensional calculations on these devices to reveal that higher current densities (and hence local recombination rates losses) arise near the front facet due spatial hole burning non-uniformity strongly affected laser geometry, which more severe for longer resonators less reflectivity. Specifically, we with a segmented p-contact directly...

Single longitudinal mode continuous-wave operation of distributed-feedback (DFB) laser diodes based on GaN is demonstrated using laterally coupled 10th-order surface Bragg gratings. The gratings consist V-shaped grooves alongside a 1.5 µm wide p-contact stripe fabricated by electron-beam lithography and plasma etching. By varying the period grating, lasing wavelength could be adjusted between 404.8 408.5 nm. feasibility this device concept was confirmed mode-hop-free up to an optical output...

We present a high-power ridge waveguide distributed feedback (DFB) laser with high-reflective coating and phase shift section at the rear facet. The is realized by means of micro heater that placed parallel to uniform grating. This type easy integrate into existing designs allows adjusting controlling spectral behavior shifting facet condition, which makes it possible overcome challenges mode-hop-free tuning regular DFB lasers highly reflective cleaved Accordingly, we use device quantify...

We present a low-temperature flip-chip-based mounting technology, enabling integration of indium phosphide (InP)-based chiplets on BiCMOS. The process temperatures well below 200°C allow to mount chips with limited temperature budget without degrading the device performance. To ensure good scalability, repeatability and flexibility in terms complex transitions we use pillar-based approach instead popular bump array technique. Thermal simulations prove that increase thermal resistances due is...

Asymmetric photon density (recombination-rate) along the high-power diode laser cavity leads to longitudinal-spatialhole- burning (LSHB), which limits maximum output power. Here, we summarize recent investigations on impact of LSHB current (longitudinal) and carrier (lateral longitudinal) distribution hence total-recombination for continuous-wave (CW) operations. Custom lasers with 90 μm stripe 3000-6000 resonator have been fabricated segmented p-side contact measure local backside...

Cold atom based quantum sensors require robust and miniaturized optical systems for applications on mobile platforms. A micro-integrated system (volume ∼25 mL) trapping manipulation of neutral atoms is presented. This setup focuses precisely overlaps two high power laser beams (1064 nm, up to 2W total, wR = 34 µm) launched via a single-mode, polarization maintaining fiber, thereby realizing crossed beam dipole trap (ODT). Adhesive bonding qualified in application relevant geometries material...

Laser diode benches (LDBs) with lasing wavelength of 808 nm were developed, manufactured and endurance-tested for utilization as pump lasers the Nd:YAG oscillator in climate satellite MERLIN. The LDBs combine customized TE-polarized GaAs-based 5-mm minibars fast axis collimation lenses to produce a reliable, space qualified component at optical power 63 W per minibar. Accelerated life tests 20 are presented. Except small increase threshold current, no wear out operating current or sudden...

In this paper we report on the influence of heterostructure design (InAlGa)N-based UV-B LEDs grown by metalorganic vapor phase epitaxy sapphire substrates degradation behavior device. Two types with different design, resulting in peak-wavelengths about 290 nm and 310 nm, respectively, were stressed at a constant operation current 100 mA heat sink temperature 20°C. Electro-optical characterization over 1.000 h shows two modes respect to change emission spectrum leakage current. The first...

Electrical and optical excitation of the active region a UVB LED chip was combined while imaging its in-plane lateral light emission by UV camera. This made it possible to distinguish between spatial distribution in current density efficiency radiative recombination charge carriers. It is demonstrated that degradation more prominent areas where local increased throughout long-term operation. will be shown how intensity distributions UVC LEDs are affected operation current, design, mesa edges.

Abstract A distributed feedback laser with integrated quarter‐wave phase shift and more than 100 mW optical output power at an emission wavelength of 780 nm is presented. The provides mode‐hop‐free tuning over a wide range injections currents operating temperatures by design can serve as enabling component for complex systems such chips additional monolithically amplifiers, chip arrays sources hybrid photonic circuits.

A bonding technology using electroplated Au microstuds for ultraviolet (UV) light-emitting diodes (LEDs) has been investigated. studs with diameter, height, and pitch of about 15, 8, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$30~\mu \text{m}$ </tex-math></inline-formula> , respectively, were on standard UV LED chips wafer level. The parameters the thermocompression (temperature, force, time) varied, a...

Lasing emission at multiple wavelengths can be used in different sensing applications and 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 common front section. These elements individually addressable biased one time for wavelength selection. The drawback of RW combination is observable spatial characteristics...

Experiment and simulation of high power diode lasers reveals a longitudinally-varying current density profile, due to spatial hole-burning. Current crowding at the front facet increases with cavity length bias, limits achievable power.

In this paper we demonstrate InP chiplet heterointegration on SiGe-BiCMOS carriers for mm-wave applications. A flip-chip type of assembly with indium-based microbumps allows seamless integration minimal losses up to more than 300 GHz. single-stage InP-HBT power amplifier was used highlight the functionality approach.

Degradation of GaN-based laser diodes after some time operation appears usually as raised threshold current, lower slope efficiency, or increased voltage. We investigate stressed and non-stressed using micro-electroluminescence (μEL) micro-photoluminescence (μPL). In μEL, the device exhibits darker regions, which are correlated with a red-shifted emission. Both observations indicate carrier density in these areas. Our μPL measurements do not suggest corresponding defect regions. This study...

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

Laser diode half-bars with 16 emitters were manufactured and qualified for pulsed high-power operation on the satellite MERLIN. Stress accelerated life tests of 20 laser performed 5•10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">9</sup> shots. No single emitter failure was detected resulting in 99.99% reliability over mission lifetime.