16 × 112 Gbps directly modulated membrane laser array for co-packaged interconnects.

A low-cost and low-power-consumption optical transmitter with a narrow shoreline is crucial for short-reach optical communication. To increase the shoreline bandwidth density (Gbps/mm) at low cost, multiple optical components, including lasers, should be integrated on a single chip. In this study, we develop a sixteen-channel membrane laser array integrated with silica-based spot-size convertors on a SiO/Si substrate, with a footprint of 1.

Quasi-continuous tuning of a 1.3-µm-wavelength superstructure grating distributed Bragg reflector laser by enhancing carrier-induced refractive index change.

To overcome the limitation of the small tuning range of 1.3-µm-wavelength distributed Bragg reflector (DBR) lasers using the carrier-plasma effect, we designed a DBR structure with InAlAs carrier confinement layers and an InGaAlAs core layer. We found that the enhanced carrier density and small effective mass of electrons in the core layer of the DBR regions resulted in a wide Bragg wavelength shift.

Elevation of sensitivity to anticancer agents of human lung adenocarcinoma A549 cells by knockdown of claudin-2 expression in monolayer and spheroid culture models.

Claudins, tight junctional proteins, regulate the paracellular permeability of ions and small molecules. Claudin-2 is highly expressed in human lung adenocarcinoma cells and is involved in the up-regulation of cell proliferation. However, the effect of claudin-2 on cellular sensitivity to anticancer agents has not been clarified.

Systematic study of thresholdless oscillation in high-β buried multiple-quantum-well photonic crystal nanocavity lasers.

Buried multiple-quantum-well (MQW) 2D photonic crystal cavities (PhC) achieve low non-radiative recombination and high carrier confinement thus making them highly efficient emitters. In this study, we have investigated the lasing characteristics of high-β(spontaneous emission coupling factor) buried MQW photonic crystal nanocavity lasers to clarify the theoretically-predicted thresholdless operation in high-β nanolasers. The strong light and carrier confinement and low non-radiative recombination in our nanolasers have enabled us to clearly demonstrate very smooth lasing transition in terms of the light-in vs light-out curve and cavity linewidth.

All-optical switching for 10-Gb/s packet data by using an ultralow-power optical bistability of photonic-crystal nanocavities.

An all-optical packet switching using bistable photonic crystal nanocavity memories was demonstrated for the first time. Nanocavity-waveguide coupling systems were configured for 1 × 1, 1 × 2, and 1 × 3 switches for 10-Gb/s optical packet, and they were all operated with an optical bias power of only a few μW. The power is several magnitudes lower than that of previously reported all-optical packet switches incorporating all-optical memories.

Clathrin-dependent endocytosis of claudin-2 by DFYSP peptide causes lysosomal damage in lung adenocarcinoma A549 cells.

Claudins are tight junctional proteins and comprise a family of over 20 members. Abnormal expression of claudins is reported to be involved in tumor progression. Claudin-2 is highly expressed in lung adenocarcinoma tissues and increases cell proliferation, whereas it is not expressed in normal tissues.

Quercetin Decreases Claudin-2 Expression Mediated by Up-Regulation of microRNA miR-16 in Lung Adenocarcinoma A549 Cells.

Claudin-2 is highly expressed in human lung adenocarcinoma tissues and cells. Knockdown of claudin-2 decreases cell proliferation and migration. Claudin-2 may be a novel target for lung adenocarcinoma.

Novel approach for chirp and output power compensation applied to a 40-Gbit/s EADFB laser integrated with a short SOA.

We propose a novel approach for simultaneously controlling the chirp and increasing the output power of an EADFB laser by monolithically integrating a short-cavity SOA. We achieved a 40-Gbit/s 5-km SMF transmission at a wavelength of 1.55 μm by using an EADFB SOA with a lower power consumption than a stand-alone EADFB laser.

Heterogeneously integrated photonic-crystal lasers on silicon for on/off chip optical interconnects.

We demonstrate the continuous-wave operation of lambda-scale embedded active-region photonic-crystal (LEAP) lasers at room temperature, which we fabricated on a Si wafer. The on-Si LEAP lasers exhibit a threshold current of 31 μA, which is the lowest reported value for any type of semiconductor laser on Si. This reveals the great potential of LEAP lasers as light sources for on- or off-chip optical interconnects with ultra-low power consumption in future information communication technology devices including CMOS processors.

Directly modulated buried heterostructure DFB laser on SiO₂/Si substrate fabricated by regrowth of InP using bonded active layer.

We describe the growth of InP layer using an ultrathin III-V active layer that is directly bonded to SiO₂/Si substrate to fabricate a buried heterostructure (BH) laser. Using a 250-nm-thick bonded active layer, we succeeded in fabricating a BH distributed feedback (DFB) laser on SiO₂/Si substrate. The use of a lateral current injection structure is important for forming a p-i-n junction using bonded thin film.

Nuclear distribution of claudin-2 increases cell proliferation in human lung adenocarcinoma cells.

Claudin-2 is expressed in human lung adenocarcinoma tissue and cell lines, although it is absent in normal lung tissue. However, the role of claudin-2 in cell proliferation and the regulatory mechanism of intracellular distribution remain undefined. Proliferation of human adenocarcinoma A549 cells was decreased by claudin-2 knockdown together with a decrease in the percentage of S phase cells.

InGaAs nano-photodetectors based on photonic crystal waveguide including ultracompact buried heterostructure.

Ultrasmall InGaAs photodetectors based on a photonic crystal waveguide with a buried heterostructure (BH) were demonstrated for the first time. A sufficiently high DC responsivity of ~1 A/W was achieved for the 3.4-μm-long detector.

Ultralow-energy and high-contrast all-optical switch involving Fano resonance based on coupled photonic crystal nanocavities.

We experimentally and theoretically clarified that a Fano resonant system based on a coupled optical cavity has better performance when used as an all-optical switch than a single cavity in terms of switching energy, contrast, and operation bandwidth. We successfully fabricated a Fano system consisting of doubly coupled photonic-crystal (PhC) nanocavities, and demonstrated all-optical switching for the first time. A steep asymmetric transmission spectrum was clearly observed, thereby enabling a low-energy and high-contrast switching operation.

A flat-output widely tunable laser based on parallel-ring resonator integrated with electroabsorption modulator.

We present a novel parallel-ring-resonator tunable laser monolithically integrated with an InGaAlAs electroabsorption modulator. The fabricated tunable laser exhibits stable wavelength tuning with a step of 200 GHz over a wide tuning range of 35 nm, achieved with a single electrode control. The variation in the laser output power with wavelength tuning is less than 1 dB even at an injected tuning current of 20 mA.

Narrow linewidth operation of buried-heterostructure photonic crystal nanolaser.

We investigate the spectral linewidth of a monolithic photonic crystal nanocavity laser. The nanocavity laser is based on a buried heterostructure cavity in which an ultra-small InGaAsP active region is embedded in an InP photonic crystal. Although it was difficult to achieve narrow linewidth operation in previously reported photonic crystal nanocavity lasers, we have successfully demonstrated a linewidth of 143.

Increase in claudin-2 expression by an EGFR/MEK/ERK/c-Fos pathway in lung adenocarcinoma A549 cells.

In human adenocarcinoma, claudin-2 expression is higher than that in normal lung tissue, but the regulatory mechanism of its expression has not been clarified. In human adenocarcinoma A549 cells, claudin-2 level time-dependently increased under the control conditions. In contrast, claudin-1 expression remained constant for 24h.

Room-temperature continuous-wave operation of lateral current injection wavelength-scale embedded active-region photonic-crystal laser.

We have developed a wavelength-scale embedded active-region photonic-crystal laser using lateral p-i-n structure. Zn diffusion and Si ion implantation are used for p- and n-type doping. Room-temperature continuous-wave lasing behavior is clearly observed from the injection current dependence of the output power, 3dB-bandwidth of the peak, and lasing wavelength.

40-Gb/s directly-modulated photonic crystal lasers under optical injection-locking.

CMOS integrated circuits (IC) usually requires high data bandwidth for off-chip input/output (I/O) data transport with sufficiently low power consumption in order to overcome pin-count limitation. In order to meet future requirements of photonic network interconnect, we propose an optical output device based on an optical injection-locked photonic crystal (PhC) laser to realize low-power and high-speed off-chip interconnects. This device enables ultralow-power operation and is suitable for highly integrated photonic circuits because of its strong light-matter interaction in the PhC nanocavity and ultra-compact size.

All-optical memory based on injection-locking bistability in photonic crystal lasers.

We have demonstrated an all-optical memory by using InGaAsP/InP buried heterostructure photonic crystal (BH-PhC) lasers. We achieved distinct optical injection locking bistability in an ultra-compact active region (4 × 0.3 × 0.

20-Gbit/s directly modulated photonic crystal nanocavity laser with ultra-low power consumption.

We have demonstrated an ultracompact buried heterostructure photonic crystal (PhC) laser, consisting of an InGaAsP-based active region (5.0 x 0.3 x 0.

Claudin-2 knockdown decreases matrix metalloproteinase-9 activity and cell migration via suppression of nuclear Sp1 in A549 cells.

Aims: Claudin expression is altered in lung cancer, but the pathophysiological role of claudin is not well understood. We examined the effect of claudin-2 expression on cell migration using human adenocarcinoma A549 cells.

Main Methods: The mRNA level was measured by real time polymerase chain reaction.

Decrease in claudin-2 expression enhances cell migration in renal epithelial Madin-Darby canine kidney cells.

Migration of renal epithelial cells increases after renal tubular damage, but its mechanism has not been clarified in detail. Hyperosmotic stress increased a cellular injury concomitant with a decrease in mRNA and protein expression of claudin-2 in renal tubular epithelial Madin-Darby canine kidney cells. We hypothesized that claudin-2 is involved in the regulation of cell migration.

All-optical wavelength-routing switch with monolithically integrated filter-free tunable wavelength converters and an AWG.

We present a compact 4x8 wavelength-routing switch that monolithically integrates fast tunable wavelength converters (TWCs) and an arrayed-waveguide grating (AWG) for optical packet switching. The TWC consists of a double-ring-resonator-coupled tunable laser which allows rapid and stable switching, and an optical gate based on a parallel amplifier structure which prevents an input optical signal from being routed through the AWG (filter-free operation). A deep-ridge waveguide technology, employed for the AWG and ring resonators, facilitates the fabrication of the switch and makes the device compact.

All-optical on-chip bit memory based on ultra high Q InGaAsP photonic crystal.

We demonstrate all-optical bit memory operation with photonic crystal (PhC) nanocavities based on an InGaAsP substrate with a band gap at a wavelength of about 1.3 microm. The optical bistability is based on a refractive index modulation caused by carrier-plasma dispersion.