Jesper Berggren

Large-area InP-based crystalline nanomembrane flexible photodetectors

Large-area (3x3 mm(2)) flexible photodetectors were realized, based on crystalline InP semiconductor nanomembranes transferred to flexible polyethylene terephthalate substrates. Very low dark curre ...

Highly strained InGaAs∕GaAs multiple quantum-wells for laser applications in the 1200–1300 nm wavelength regime

We report on metalorganic vapor-phase epitaxy growth optimization and properties of highly strained InGaAs∕GaAs quantum-well (QW) structures with emission wavelength beyond 1200 nm. It is observed that a sufficiently high V/III ratio in combination with low growth temperature is critical for preserved layer integrity when increasing the strain. Multiple QWs with up to five wells are realized without any degradation in photoluminescence intensity or broad-area laser performance at an emission wavelength of 1240 nm with threshold current density below 70A∕cm2 per well.

Suppression of Higher Order Transverse and Oxide Modes in 1.3-

It is shown, by a systematic variation of design parameters, that the use of an inverted surface relief is very effective for suppressing higher order transverse modes in oxide confined 1.3-mum InGaAs vertical-cavity surface-emitting lasers (VCSELs). Single-mode emission is achieved for a large variety of oxide aperture and surface relief diameters, with optimum designs, having a surface relief with a diameter half of that of the oxide aperture, producing 1.1-1.3 mW of single-mode power. It is also shown that the anti-phase layer employed to enable the use of an inverted surface relief is effective for suppressing oxide modes that otherwise appear in oxide confined VCSELs with a large detuning between the gain peak and the cavity resonance

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It is shown that n-type doping of AlGaAs/GaAs distributed Bragg reflectors (DBRs) grown by metal-organic vapor-phase epitaxy has a profound negative impact on the performance of vertical-cavity sur ...

m InGaAs VCSELs by an Inverted Surface Relief

We report on the performance and analysis of 1.3μm range InGaAs∕GaAs vertical-cavity surface-emitting lasers (VCSELs) with an integrated mode filter consisting of a patterned silicon layer on the top distributer Bragg reflector. In this way, 1mW of single mode power is obtained from a device with a wavelength of 1265nm and a threshold current of 2.6mA at room temperature. An effective index model is used to extract the internal and external losses of the VCSEL structure and to predict the modal losses with and without mode filter, thereby providing a useful design tool for single mode VCSELs.

Optical loss and interface morphology in AlGaAs/GaAs distributed Bragg reflectors

A comprehensive simulation study of InGaAsP (well)/InGaAlAs(barrier) 1.55 /spl mu/m strain-compensated MQW lasers is presented. For MQWs, a uniform vertical distribution of holes is achieved due to a reduced effective hole confinement energy by optimizing the bandgap and strain of the barriers and p-doping in the active region. Some preliminary results are also presented for the manufactured lasers using these QWs indicating a good material platform.

1.3 μm InGaAs vertical-cavity surface-emitting lasers with mode filter for single mode operation

InSb-based quantum dots grown by metal-organic vapor-phase epitaxy (MOVPE) on InAs substrates are studied for use as the active material in interband photon detectors. Long-wavelength infrared (LWIR) photoluminescence is demonstrated with peak emission at 8.5 µm and photoresponse, interpreted to originate from type-II interband transitions in a p-i-n photodiode, was measured up to 6 µm, both at 80 K. The possibilities and benefits of operation in the LWIR range (8-12 µm) are discussed and the results suggest that InSb-based quantum dot structures can be suitable candidates for photon detection in the LWIR regime.

Design optimization of InGaAsP-InGaAlAs 1.55 /spl mu/m strain-compensated MQW lasers for direct modulation applications

In this paper, the effect of barrier bandgap and composition on the optical performance of 1.55-mum InGaAsP/InGaAsP and InGaAsP/InGaAlAs multiple quantum-well structures and Fabry-Perot lasers is evaluated experimentally. Direct vertical carrier transport measurements were performed through strain-compensated multiple quantum-well (MQW) test structures using femto-second laser pulse excitation and time-resolved photoluminescence up-conversion method. MQW test structures were grown with different barrier composition (InGaAsP and InGaAlAs) and barrier bandgap (varied from lambdag= 1440 to 1260 nm) having different conduction band DeltaEc and valence band discontinuity DeltaEv, while keeping the same InGaAsP well composition for all the structures. The ambipolar carrier transport was found to be faster in the structures with lower valence band discontinuity DeltaEv. Regrown semi-insulating buried heterostructure Fabry-Perot (SIBH-FP) lasers were fabricated from similar QWs and their static light-current-voltage characteristics (including optical gain and chirp spectra below threshold) and thermal characteristics were measured. Lasers with InGaAlAs barrier showed improved high-temperature operation, higher optical gain, higher differential gain, and lower chirp, making them suitable candidates for high-bandwidth directly modulated uncooled laser applications

Photoluminescence and photoresponse from InSb/InAs-based quantum dot structures

Epitaxial lateral overgrowth of InP was performed on patterned silicon-on-insulator (SOI) and compared with that on Si substrates in a low pressure hydride vapor phase epitaxy system. The InP was c ...

The effect of barrier composition on the vertical carrier transport and lasing properties of 1.55-/spl mu/m multiple quantum-well structures

In order to fit with the present and future needs of the Datacom transceiver market, newly designed high rate transmitter optical subassemblies (TOSAs) have to be compact, low cost and compatible with mass production. We propose here an innovative design strategy that reaches all these targets by integrating a 10Gbps 850nm VCSEL laser diode and its laser driver with other functionalities (e.g. power monitoring and thermal monitoring) in a small form factor package. Taking advantages of the optical properties of the VCSEL and using flip-chip techniques, the transmitter exhibits excellent hyperfrequency performances and compatibility with mass production due to the use of collective manufacturing technologies and passive optical alignment. This versatile approach is also applicable to high rate receivers, parallel optics emitters, and singlemode low cost transmitter integrating long wavelength VCSELs.