TriLumina develops and manufactures flip-chip VCSEL technology used in 3D sensing applications that must meet automotive grade 1 temperature range (-40˚C to 125˚C) performance and be tested to high reliability standards and criteria (AEC-Q102). Advances in VCSEL efficiency, performance and automotive qualification of TriLumina’s selfhermetic flip-chip VCSEL are discussed. TriLumina’s VCSEL-on-board (VoB), surface-mount technology VCSEL is introduced.
KEYWORDS: Vertical cavity surface emitting lasers, Modulation, Aluminum nitride, Distance measurement, Light sources and illumination, Time of flight imaging, Time of flight cameras, Time of flight range image sensors, LIDAR
The design and optimization of two-dimensional VCSEL arrays operating with duty-cycles from 2 to 5% (quasicontinuous- wave or QCW) operating at 940 nm are presented. Designs for nominal 8 W and 100 W peak power using TriLumina’s flip-chip-bondable, back-side-emitting VCSELs are reviewed. Performance as a function of duty cycle, including peak power output, spectral width and beam divergence are presented. Performance from -40°C to 125°C, corresponding to automotive grade 1 requirements, is reviewed. Optimization of the VCSEL arrays as a function of the number of emitters per chip is analyzed for trends in wall-plug efficiency, slope efficiency and operating conditions.
808 nm QCW bars were fabricated and mounted with hard solder technology onto H-mounts and G-stacks. At room
temperature, reliable operation has been demonstrated at 400W at 400A per single 1-cm bar and for a G-stack at 3kW at
around 300A. High temperature reliable operation has been demonstrated for both devices up to 95°C. Both types of
devices were tested at various pulse widths and duty cycles. Both optical power and wavelength dependencies on the
various conditions have been studied.
This paper presents the results obtained by Intense during the development of its 2 kW stack using Quantum Well
Intermixing (QWI). A 200 W QCW bar operating at 808 nm has been designed with a 1 mm long cavity of which only a
fraction is actively pumped. The bar has an 80% fill factor, and ten 200 W bars were stacked vertically in a G-type
package with a 417 μm bar-to-bar pitch. The resulting compact emission area makes the stack compatible with most
existing laser and electro-optic systems. A lifetime of 1x109 shots has been obtained with no measurable degradation.
Novel types of laser diode array with a 100% filling factor at the emission facet are reported. The arrays utilize both
parallel and tapered cavity emitters that are connected via a common Laterally Unconfined Non-Absorbing Mirror
(LUNAM) defined with quantum-well intermixing technology at 808 nm wavelength. Two LUNAM array types are
considered: incoherent (weakly coupled) and coherent (diffraction coupled).
Incoherent LUNAM arrays benefit from a reduced power density at the facet, improving reliability, and a near-uniform
intensity distribution across the array aperture. Stacked laser diode arrays built with LUNAM bars deliver 950 W power
under QCW operation with <5% degradation at 1.9×108 shots.
Novel coherent arrays are realized using a monolithically integrated LUNAM Talbot cavity. The devices produce a
single-lobed horizontal far-field pattern over a limited current range with <10% slope efficiency penalty compared to an
uncoupled case. The LUNAM arrays are promising candidates for high-power, high-brightness and high-reliability
operation.
In this paper we report the development of high power high brightness semiconductor laser chips using a combination of
quantum well intermixing (QWI) and novel laser designs including laterally unconfined non-absorbing mirrors
(LUNAM). We demonstrate both multi-mode and single-mode lasers with increased power and brightness and reliability
performance for the wavelengths of 980 nm, 940 nm, 830 nm and 808 nm.
Photonic integration of large arrays of high power, single mode lasers using quantum well intermixing technology in a small form-factor package is described. Lifetime analysis reveals excellent reliability of large element laser arrays packaged into small form-factor optical systems.
Quantum well intermixing (QWI) of the facet regions of a semiconductor laser can significantly improve the COD of the device giving high kink power and high reliability. A novel epitaxy design incorporating a graded 'V-profile' layer allows for a reduced vertical far-field and simultaneously suppresses higher order modes to give high power operation. Furthermore, the 'V-profile' layer provides a robust design to improve the ridge etch tolerance to give excellent device performance uniformity across an array. Very large arrays of individually addressable lasers (up to 100 elements) are reported with small pitch size (~100 μm), high single mode power (up to 300 mW) and high uniformity.
Quantum well intermixing (QWI) can bring considerable benefits to the reliability and performance of high power laser diodes by intermixing the facet regions of the device to increase the band-gap and hence eliminate absorption, avoiding catastrophic optical damage (COD). The non-absorbing mirror (NAM) regions of the laser cavity can be up to ~20% of the cavity length, giving an additional benefit on cleave tolerances, to fabricate very large element arrays of high power, individually addressable, single mode lasers. As a consequence, large arrays of single mode lasers can bring additional benefits for packaging in terms of hybrization and integration into an optics system. Our QWI techniques have been applied to a range of material systems, including GaAs/AlGaAs, (Al)GaAsP/AlGaAs and InGaAs/GaAs.
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