Petri Melanen

Effects of rapid thermal annealing on strain-compensated GaInNAs/GaAsP quantum well structures and lasers

Strain-compensated GaInNAs/GaAsP quantum well structures and lasers were grown by gas-source molecular beam epitaxy using a rf-plasma nitrogen radical beam source. Effects of rapid thermal annealing on the optical properties of GaInNAs/GaAsP quantum well structures as well as laser diodes were examined. It was found to significantly increase the photoluminescence from the quantum wells and reduce the threshold current density of the lasers, mainly due to a removal of N-induced nonradiative centers from GaInNAs wells.

Effects of Lateral Diffusion on the Temperature Sensitivity of the Threshold Current for 1.3-

We present an experimental and theoretical investigation of the temperature dependence of the threshold current for double quantum well GaInNAs-GaAs lasers in the temperature range 10 degC-110 degC. Pulsed measurements of the threshold current have been performed on broad and narrow ridge wave guide (RWG) lasers. The narrow RWG lasers exhibit high characteristic temperatures (T0) of 200 K up to a critical temperature (Tc), above which T0 is reduced by approximately a factor of 2. The T0-values for broad RWG lasers are significantly lower than those for the narrow RWG lasers, with characteristic temperatures on the order of 100 (60) K below (above) Tc. Numerical simulations, using a model that accounts for lateral diffusion effects, show good agreement with experimental data and reveal that a weakly temperature dependent lateral diffusion current dominates the threshold current for narrow RWG lasers.

\mu{\hbox {m}}

Ridge waveguide 1.3 mum GaInNAs lasers were fabricated from high quality double quantum well material grown by molecular beam epitaxy. Short cavity (250 mum) lasers have low threshold currents and small temperature dependencies of threshold current and slope efficiency, with a characteristic temperature of the threshold current as high as 200 K. The temperature stability allows for uncooled 2.5 Gb/s operation up to temperatures as high as 110 degrees C with a constant modulation voltage and only the bias current adjusted for constant average output power. Under these conditions, an extinction ratio larger than 6 dB and a spectral rms-width smaller than 2 nm are obtained.

Double Quantum-Well GaInNAs–GaAs Lasers

This paper presents the performance characteristics and reliability data of AlGaInP-based VISIBLE laser diodes emitting at the wavelengths from 630 to 670 nm. The lasers are grown by toxic gas free solid source molecular beam epitaxy.

Uncooled 2.5 Gb/s operation of 1.3 μm GaInNAs DQW lasers over a wide temperature range

Abstract Resonant cavity light-emitting diodes (RCLEDs) operating at λ≅660 nm and λ≅880 nm have been fabricated and studied. The RCLED layer structures consisted of 1−λ thick cavities sandwiched between AlGaAs distributed Bragg reflectors. The cavities were detuned to improve temperature stability and light extraction. The temperature induced red-shifts in the peak emission wavelength were found to be 0.14 and 0.22 nm °C−1 for the 660- and 880-nm devices, respectively.

High-power 600-nm-range lasers grown by solid-source molecular beam epitaxy

Abstract Monolithic top emitting resonant cavity light-emitting diodes (RC-LEDs) operating at 660 and 880 nm have been prepared using solid-source molecular beam epitaxy (SSMBE) growth. Transfer matrix based modelling together with a self-consistent model have been used to optimise the devices’ performances. Intermediate-composition barrier-reduction layers were introduced in the distributed Bragg reflector (DBR) mirrors for improving the I – V characteristics and the cavity and mirrors were detuned aiming at maximum extraction efficiency. The fabricated devices showed line widths below 15 nm, CW light power output of 8 and 22.5 mW, and wall-plug efficiencies of 3% and 14.1% in the 660 nm and 880 nm ranges, respectively, while the simulations indicate significant performance improvement possibilities.

Resonant cavity light-emitting diodes at 660 and 880 nm

We present results from measurements of the subthreshold lateral spontaneous emission profile in 1.3-mu m wavelength ridge waveguide InGaNAs quantum-well lasers using a scanning near-field optical microscopy technique. The measurements reveal the presence of significant lateral carrier diffusion which has a profound effect on the temperature dependence of the threshold current. This effect is frequently omitted when the characteristic temperature of the threshold current is considered.

Modeling and optimization of resonant cavity light-emitting diodes grown by solid source molecular beam epitaxy

Dilute-nitride lasers with record performances have been used to build uncooled transceivers and failure free 10 Gb/s optical transmission was achieved over 815 m of multimode Corning InfiniCor fiber under the LRM standard.

Direct Observation of Lateral Carrier Diffusion in Ridge Waveguide InGaNAs Lasers

Laterally coupled diode lasers emitting at 1.3 um are presented. Devices were fabricated with distances between ridges varying from 2.76 um to 8.32 um. Electronic coupling effects are investigated by individually varying the currents in each ridge while monitoring output power. It is observed that for devices with 8.32 um separation between ridges there is minimal current sharing, whereas for 2.76 um separation there is considerable current sharing. Optical coupling is measured via the far-field, where most devices show out-of-phase locking, although in-phase locking is observed in a minority of cases. Devices therefore show conditions necessary for the observation of high speed dynamics.

10 Gb/s uncooled dilute-nitride optical transmitters operating at 1.3 µm

We describe a new coherent beam combining architecture based on passive phase-locking of two laser diodes in a Michelson external cavity on their rear facet, and their coherent combination on the front facet. As a proof-of-principle, two ridge lasers have been coherently combined with >90 % efficiency. The phase-locking range, and the resistance of the external cavity to perturbations have been thoroughly investigated. The combined power has been stabilized over more than 15 min with an optical feedback as well as with an automatic adjustment of the driving currents. Furthermore, two high-brightness high-power tapered laser diodes have been coherently combined in a similar arrangement; the combining efficiency is 70% and results in an output power of 4 W. We believe that this new configuration combines the simplicity of passive self-organizing architectures with the optical efficiency of master-oscillator power-amplifier ones.