Although traditional quantum-confined nanostructures e.g. regular quantum wells or quantum dots have achieved huge success in the field of semiconductor lasers for past decades, these traditional nanostructures are encountering the difficulty of enhancing device performance to a higher level due to their inherent gain bottleneck. In this paper, we are proposing a new super-gain nanostructure based on self-assembled well-wire complex energy-band engineering with InGaAs-based materials to break through the existing bottleneck. The nanostructure is constructed by utilizing the special strain-driven indium (In)-segregation and the growth orientation-dependent on-GaAs multi-atomic step effects to achieve the distinguished ultra-wide and uniform super-gain spectra. The structural details and its luminescence mechanism are investigated by multiple measurement means and theoretical modeling. The polarized gain spectra with the max fluctuation of <3 cm−1 in 904 nm–998 nm for transverse electric (TE) mode and 904 nm–977 nm for transverse magnetic (TM) mode are simultaneously obtained with this nanostructure. It enables an ultra-low output power fluctuation of <0.7 dB and a nearly-constant threshold power throughout an ultra-wide wavelength range under a fixed injection level. It was difficult to realize these in the past. Therefore, the described super-gain nanostructure brings a brand-new chance of developing high performance of tunable laser diodes.

It is well known that the laser diode performance will inevitably deteriorate when the device is heated. It has been a difficult issue to solve to date. In this letter, we are reporting a new solution to improve high-temperature performance of the laser diodes. The device uses a kind of directly-coupled well-wire hybrid quantum confinement (HQC) structure of the active medium based on the InGaAs-GaAs-GaAsP material system. This special HQC structure is constructed based on the strain-driven indium (In)-segregation effect and the growth orientation-dependent on-GaAs multi-atomic step effect. The measurement and analysis for the HQC laser sample show that the carrier leakage loss, the Auger recombination and gain-peak shifting due to heating are reduced in the HQC structure. It therefore increases the optical gain for lasing at high temperature. The power conversion efficiency is enhanced by > 57% and the threshold carrier density drops by > 24% at T ≥ 360 K, in comparison to the traditional quantum-well laser performance. A higher characteristic temperature of 240 K is obtained as well. It implies the better thermal stability of the HQC laser structure. These achievements show a significant prospect for developing high thermo-optic performance of laser diodes.&#xD;

A kind of new quantum confined indium (In)rich cluster (IRC) laser with polarized dual-wavelength output is first proposed and realized. Unlike conventional quantum well/dot lasers, its optical characteristics depend on the special IRC effect-formed quantum confined structure, in which the asymmetric distribution and various sizes of IRCs are generated due to high strains in the indium-based material system. It may lead to a special band structure suitable for synchronous dual-wavelength lasing generation. The mechanism of the laser operation is associated with independent carrier transitions and stimulated emissions from multiple local indium-based active regions, which have various areas and different indium contents due to the IRC effect. The sample uses InGaAs/GaAs/GaAsP as the kernel of lasing medium with the edge-emitting configuration, both facets of which are used as cavity mirrors. The experiment exhibits synchronous dual wavelengths of lasing at 970 and 980 nm in transverse electric (TE) polarization, with a total slope efficiency of 34.6% at a room temperature of 300 K. The result is of great significance in the development of new types of monolithic quantum confined lasers with dual-wavelength and polarization output.

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This Letter reports polarization-independent optical amplification over an ultrabroad spectral range by semiconductor optical amplifiers. The technique uses an InGaAs-based indium-rich cluster (IRC) quantum-confined structure as the active medium and obtains comparable optical gain for both transverse electric (TE) and transverse magnetic (TM) polarization modes in the spectral ranges of 905–1005 and 905–970 nm, respectively. The device thus provides independent optical amplification for TE and TM polarizations over a common bandwidth of 65 nm. The difference between the amplified intensities of TE and TM modes is &lt;0.5 dB. These results are attributed to the special emission mechanism of the IRC quantum-confined structure, which differs from that of conventional quantum wells or quantum dots. A preliminary analysis of this mechanism is provided.