Matrix-addressable 370nm micro-LED arrays with integrated polymer micro-lenses

This paper is about matrix-addressable 370nm micro-LED arrays with integrated polymer micro-lenses. It was presented at the 6th international conference on nitride semiconductors in 2005

Tunable single-mode fibre VCSEL using an intracavity polymer microlens

We report a tunable, single-mode vertical cavity surface-emitting laser (VCSEL) format suitable for array operation, power scaling, fiber coupling, and operation in isolated environments such as those required by atom optics. The devices are fiber VCSELs, consisting of a semiconductor gain and mirror structure separated from a mirror-coated optical fiber by an air (or vacuum) gap. The gain structure has polymer microlenses fabricated on its surface, of characteristics suitable to focus the oscillating mode on both cavity mirrors, ensuring stable fundamental mode emission and high fiber coupling efficiency. We demonstrate such devices in continuous-wave operation at 1.03 μm at room temperature, with a single-mode tuning range of 13 nm, laser threshold as low as 2.5 mW, and a maximum fiber-coupled output power of 10 mW

Tunable fiber-VCSEL with an intracavity polymer microlens

We report a tunable, single-mode fiber-VCSEL possessing a polymer microlens integrated on its gain region surface. 1.03-¿m CW operation with a 13-nm free-spectral-range-limited tuning, a 6-mW threshold and fiber-coupled output power of 10mW is demonstrated

Fabrication of planar GaN-based micro-pixel light emitting diode arrays

Micro-pixelated GaN light-emitting diodes (‘micro-LED’s) offer attractions for a wide range of applications including microdisplays, mask-free photolithography, lab-on-a-chip and bioinstrumentation [1]. Mesa dry etching methods have underpinned the development of this technology to date. Here we propose and demonstrate a new planar process which simplifies the process flow and permits individually-addressable pixelated devices to be fabricated without any obvious degradation of electrical and optical performance. The approach is based on the intrinsic high resistivity of the p-type GaN layer for pixel to pixel electrical isolation and on a CHF3 plasma treatment to dramatically reduce current leakage through the p-GaN/metal interface. Consequently, this process requires a lower number of fabrication steps than previously used processes using mesa etching for pixel definition and dielectric deposition for electrical insulation [2]. It leads to a planar active area well suited for further integration of functional micro-elements, including microfluidic-channels, microoptics or luminescent materials for colour conversion [3, 4]. This new fabrication route has been validated by fabricating and characterizing an individually addressable micro-stripe LED array emitting at 470 nm

Patterning and integration of OLED polyfluorene polymers on matrix addressable UV alInGaN micropixellated light-emitting diodes

This paper is about Patterning and integration of OLED polyfluorene polymers on matrix addressable UV alInGaN micropixellated light-emitting diodes. It was presented at Photon 06, the UK's premier conference in optics and photonics

Micro-pixel flip-chip AlInGaN LED arrays with high CW and nanosecond output power

Flip-chip AlInGaN micro-LED arrays with different wavelengths and pixel diameters have been fabricated, giving, per pixel, CW output power densities up to 32.5W/cm2 at 20mA and pulsed output of up to 150pJ in 36ns pulses

Patterning and integration of polyfluorene polymers on micro-pixellated uV alInGaN light-emitting diodes

We report the integration of micro-patterned polyfluorene conjugated polymers onto GaN-based ultraviolet (UV) micro-pixellated light-emitting diode arrays (micro-LEDs). The 64 × 64 element matrix-addressable AlInGaN devices have a pixel size of 20 µm diameter on a 50 µm pitch, emitting at 368 nm. Each array is covered with a 2.5 µm thick photo-curable deep-UV-transparent polymer and a 30 nm thick polyfluorene film. This polymer bi-layer is subsequently patterned into an array of 28 µm diameter discs aligned with the pixels of the micro-LED array. Polymer down-converted visible emission from these pattern-programmable organic/inorganic electroluminescent micro-arrays is achieved

Novel polymer systems for deep UV microlens arrays

We report for the first time a UV curable polymer with effective optical transmission below 300 nm. Through careful control of kinetics, various viscosities can be generated to optimize the film forming properties via spin coating. The transmission of the monomers and films is investigated over a spectral range which spans the 240-370 nm output of ultraviolet AlInGaN light-emitting diodes. The refractive index of the polymer has been measured by ellipsometry to give a value of 1.57 at 280 nm. Using standard lithography techniques with reactive ion etching, arrays of microlenses have been fabricated in this polymer with diameters of 30μm and below and are characterized by atomic force microscopy and confocal microscopy

Individually-addressable flip-chip AllnGaN micropixelated light emitting diode arrays with high continuous and nanosecond output power

Micropixelated blue (470nm) and ultraviolet (370nm) AlInGaN light emitting diode arrays have been fabricated in flip-chip format with different pixel diameters (72μm and 30μm at, respectively, 100 and 278 pixels/mm2). Each micro-LED pixel can be individually-addressed and the devices possess a specially designed n-common contact incorporated to ensure uniform current injection and consequently uniform light emission across the array. The flip-chip micro-LEDs show, per pixel, high continuous output intensity of up to 0.55μW/μm2 (55W/cm2) at an injection current density of 10kA/cm2 and can sustain continuous injection current densities of up to 12kA/cm2 before breakdown. We also demonstrate that nanosecond pulsed output operation of these devices with per pixel onaxis average peak intensity up to 2.9μW/μm2 (corresponding to energy of 45pJ per 22ns optical pulse) can be achieved. We investigate the pertinent performance characteristics of these arrays for micro-projection applications, including the prospect of integrated optical pumping of organic semiconductor lasers

Micro-optics in UV transparent polymer for deep UV LED applications

This article covers micro-optics in UV transparent polymer for deep UV LED applications. It was presented at the 6th International Symposium on Blue Laser and Light Emitting Diodes, in 2006