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We aim to achieve wavelength division multiplexing with a circular defect in two‐dimensional photonic crystal (CirD) laser that has an orthogonal lattice waveguide (OLW). In a simulation, we calculate the output extraction efficiency to discover a structure in which stronger optical output can be extracted for the CirD laser with OLW. Consequently, adjusting the edge face position and applying a semicircular port can strengthen the energy extracted from the edge face. This appears to be caused by changing the positional relationship between the standing wave mode and the edge face. Furthermore, the OLW‐W1 structure proposed in this report can achieve higher output extraction efficiency than the conventional OLW. The transmittance is enhanced by changing the structure near the edge face because this improves the matching of light speed in different media. [ABSTRACT FROM AUTHOR]

A circular defect in 2D photonic crystal (CirD) lasers is developed, which has the potential to achieve a target communication density of 10 Pbps cm−2 for intrachip optical communications by vertical current injection. The AlGaOx cladding layer's oxidation width strongly influences the device's light confinement and electronic resistance. Herein, samples with different oxidation widths are fabricated and the relationship between threshold power and oxidation width through photoexcitation is revealed. The optimal range of the oxidation width is found to be 349–439 nm, which can ensure low electronic resistance and low threshold power. [ABSTRACT FROM AUTHOR]

Herein a circular defect in a 2D photonic crystal (CirD) laser for wavelength division multiplexing (WDM) optical communications is theoretically analyzed. By coupling CirD lasers to a waveguide, a huge communication capacity can be expected. For example, if high‐speed, 50 Gbps laser operations are successfully achieved, WDM devices with 20 CirD lasers could achieve a communication capacity of 1 Tbps. Based on finite‐difference time‐domain (FDTD) simulation results, in this study, both current‐output and high‐frequency characteristics are investigated by solving 2D rate equations, revealing that an excessively high‐quality factor in laser cavities reduces the relaxation‐oscillation frequency. When the photon lifetime is 2 ps, which corresponds to a quality factor of ≈3000, a small threshold current of 5 μA and a high relaxation‐oscillation frequency of 40 GHz can be simultaneously obtained. These results suggest the potential of developing a WDM device using CirD lasers. [ABSTRACT FROM AUTHOR]

Extremely high etch selectivity of GaAs over AlOx is mandatory to fabricate a current blocking trench (CBT) between adjacent lasers in a photonic crystal (PhC) laser array for intra-chip optical interconnections. In this paper, selective etching of GaAs on AlOx with PhC structure is reported for the first time by using inductively coupled plasma etching with Cl2/BCl3-containing gas mixture. The etched profile of the CBT on GaAs/AlOx heterostructure with PhC structure was significantly different from that without PhC structure. By optimizing the etching conditions, the etching of the CBT was stopped at AlOx, and extremely high etch selectivity of GaAs over AlOx was achieved. Thus, we successfully fabricated the CBT in the PhC laser array. The horizontal electrical resistance between adjacent laser cavities with a 0.4 μm or wider CBT reached the instrumentation-limit of 100 MΩ, confirming the electrical isolation effect of the CBT. [ABSTRACT FROM AUTHOR]

We study energy-band engineering with nitrogen delta (δ)-doping in GaAs-related quantum structures. A tight-binding calculation indicates that the band structure can be engineered by introducing the one-dimensional doping profile of nitrogen into GaAs. Using molecular beam epitaxy, we prepare δ-doped samples of AlGaAs/GaAs quantum wells and GaAs/δ-doped nitrogen superlattice structures at the growth temperature 560 °C. Photoluminescence obtained from the samples shows a clear redshift of the spectral peak positions dependent on the nitrogen coverage. The transition energies of the superlattice structures agree well with those obtained from photoreflectance, indicating the feasibility of band modification with a single or a multiple nitrogen δ-doped layer. [ABSTRACT FROM AUTHOR]