InAsP Quantum Dot-Embedded InP Nanowires toward Silicon Photonic Applications.

Quantum dot (QD) emitters on silicon platforms have been considered as a fascinating approach to building next-generation quantum light sources toward unbreakable secure communications. However, it has been challenging to integrate position-controlled QDs operating at the telecom band, which is a crucial requirement for practical applications. Here, we report monolithically integrated InAsP QDs embedded in InP nanowires on silicon. The positions of QD nanowires are predetermined by the lithography of gold catalysts, and the 3D geometry of nanowire heterostructures is precisely controlled. The InAsP QD forms atomically sharp interfaces with surrounding InP nanowires, which is in situ passivated by InP shells. The linewidths of the excitonic (X) and biexcitonic (XX) emissions from the QD and their power-dependent peak intensities reveal that the proposed QD-in-nanowire structure could be utilized as a non-classical light source that operates at silicon-transparent wavelengths, showing a great potential for diverse quantum optical and silicon photonic applications.

III-V nanowires on silicon (100) as plasmonic-photonic hybrid meta-absorber.

Integration of functional infrared photodetectors on silicon platforms has been gaining attention for diverse applications in the fields of imaging and sensing. Although III-V semiconductor is a promising candidate for infrared photodetectors on silicon, the difficulties in directly growing high-quality III-V on silicon and realizing functionalities have been a challenge. Here, we propose a design of III-V nanowires on silicon (100) substrates, which are self-assembled with gold plasmonic nanostructures, as a key building block for efficient and functional photodetectors on silicon. Partially gold-coated III-V nanowire arrays form a plasmonic-photonic hybrid metasurface, wherein the localized and propagating plasmonic resonances enable high absorption in III-V nanowires. Unlike conventional photodetectors, numerical calculations reveal that the proposed meta-absorber exhibits high sensitivity to the polarization, incident angle, wavelength of input light, as well as the surrounding environment. These features represent that the proposed meta-absorber design can be utilized not only for efficient infrared photodetectors on silicon but for various sensing applications with high sensitivity and functionality.

InGaAs-GaAs Nanowire Avalanche Photodiodes Toward Single-Photon Detection in Free-Running Mode.

Single-photon detection at near-infrared (NIR) wavelengths is critical for light detection and ranging (LiDAR) systems used in imaging technologies such as autonomous vehicle trackers and atmospheric remote sensing. Portable, high-performance LiDAR relies on silicon-based single-photon avalanche diodes (SPADs) because of their extremely low dark count rate (DCR) and afterpulsing probability, but their operation wavelengths are typically limited up to 905 nm. Although InGaAs-InP SPADs offer an alternative platform to extend the operation wavelengths to eye-safe ranges, their high DCR and afterpulsing severely limit their commercial applications. Here we propose a new separate absorption and multiplication avalanche photodiode (SAM-APD) platform composed of vertical InGaAs-GaAs nanowire arrays for single-photon detection. Among a total of 4400 nanowires constituting one photodiode, each avalanche event is confined in a single nanowire, which means that the avalanche volume and the number of filled traps can be drastically reduced in our approach. This leads to an extremely small afterpulsing probability compared with conventional InGaAs-based SPADs and enables operation in free-running mode. We show a DCR below 10 Hz, due to reduced fill factor, with photon count rates of 7.8 MHz and timing jitter less than 113 ps, which suggest that nanowire-based NIR focal plane arrays for single-photon detection can be designed without active quenching circuitry that severely restricts pixel density and portability in NIR commercial SPADs. Therefore, the proposed work based on vertical nanowires provides a new degree of freedom in designing avalanche photodetectors and could be a stepping stone for high-performance InGaAs SPADs.

GaSb-based mid infrared photonic crystal surface emitting lasers.

We demonstrated for the first time above room temperature (RT) GaSb-based mid-infrared photonic crystal surface emitting lasers (PCSELs). The lasers, under optical pumping, emitted at λ(lasing)~2.3µm, had a temperature insensitive line width of 0.3nm, and a threshold power density (P(th)) ~0.3KW/cm2 at RT. Type-I InGaAsSb quantum wells were used as the active region, and the photonic crystal, a square lattice, was fabricated on the surface to provide optical feedback for laser operation and light coupling for surface emission. The PCSELs were operated at temperatures up to 350K with a small wavelength shift rate of 0.21 nm/K. The PCSELs with different air hole depth were studied. The effect of the etched depth on the laser performance was also investigated using numerical simulation based on the coupled-wave theory. Both the laser wavelength and the threshold power decrease as the depth of the PC becomes larger. The calculated results agree well with the experimental findings.

Construction of adenovirus vector expressing TIP30 and its tumor suppressive effect in vitro and in vivo / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To construct an adenovirus vector expressing TIP30 gene (Ad-TIP30) and investigate its tumor suppressive effect in vitro and in vivo.</p><p><b>METHODS</b>Ad-Easy system was used to construct Ad-TIP30 by recombination in E. coli. The virus was packaged in 293 cells and subsequently identified valid. Human HCC (hepatocellular carcinoma) cell lines HepG(2) (p53-wt), PLC/PRL/5 (p53-mut), and osteosarcoma cell line Saos-2 (p53-null) with different p53 genotype were infected with Ad-TIP30 and control virus with Ad-GFP, respectively. The tumor suppressive effect of TIP30 in vitro was examined by trypan blue exclusion method. The expression level of p53 was determined by RT-PCR before and after Ad-TIP30 infection. The in vivo tumor suppressive effect was detected in nude mice with human HCC xenograft.</p><p><b>RESULTS</b>The expression of TIP30 significantly inhibited the in vitro proliferation of tumor cells, among which HepG(2) with wild type p53 gene was most susceptible to Ad-TIP30 induced growth inhibition. The expression of p53 was significantly up-regulated in HepG(2) after Ad-TIP30 infection as determined by RT-PCR. The growth in nude mice of HCC infected with Ad-TIP30 was significantly inhibited with an inhibition rate of 62.9%.</p><p><b>CONCLUSION</b>The expression of TIP30 could inhibit the proliferation of tumor cell lines through both p53-dependent and p53-independent pathways, and may be used as a potential tool for cancer therapy.</p>