Yingyan Huang

An Ultracompact Optical Mode Order Converter

We describe the design and fabrication of an ultracompact optical mode order converter employing submicron waveguides. The mode converter can realize optical mode conversion between zeroth- and first-order optical modes with a device footprint less than 18 mum by 3 mum. The optical mode converter could be employed in various types of photonic integrated circuits where optical mode order conversion is needed

Enhanced radiation-loss-based radial-waveguide-coupled electrically pumped microresonator lasers with single-directional output

A novel enhanced radiation-loss (ERL)-based radial waveguide coupling mechanism for microresonator lasers is experimentally demonstrated for the first time, to the best of our knowledge, resulting in single-directional output from the lasers. A 20 microm diameter InGaAsP/InP electrically pumped microresonator laser in the form of a microcylinder resonator integrated with a transparent ERL radial output coupler is designed and fabricated. Measurement shows a low 1.5 mA lasing threshold and a relatively high output power of >0.4 mW.

Silicon/III-V laser with super-compact diffraction grating for WDM applications in electronic-photonic integrated circuits.

We have demonstrated a heterogeneously integrated III-V-on-Silicon laser based on an ultra-large-angle super-compact grating (SCG). The SCG enables single-wavelength operation due to its high-spectral-resolution aberration-free design, enabling wavelength division multiplexing (WDM) applications in Electronic-Photonic Integrated Circuits (EPICs). The SCG based Si/III-V laser is realized by fabricating the SCG on silicon-on-insulator (SOI) substrate. Optical gain is provided by electrically pumped heterogeneous integrated III-V material on silicon. Single-wavelength lasing at 1550 nm with an output power of over 2 mW and a lasing threshold of around 150 mA were achieved.

Multi-level multi-thermal-electron FDTD simulation of plasmonic interaction with semiconducting gain media: applications to plasmonic amplifiers and nano-lasers

Interactions between a semiconducting gain medium and confined plasmon-polaritons are studied using a multilevel multi-thermal-electron finite-difference time-domain (MLMTE-FDTD) simulator. We investigated the amplification of wave propagating in a plasmonic metal-semiconductor-metal (MSM) waveguide filled with semiconductor gain medium and obtained the conditions required to achieve net optical gain. The MSM gain waveguide is used to form a plasmonic semiconductor nano-ring laser(PSNRL) with an effective mode volume of 0.0071 microm3, which is about an order of magnitude smaller than the smallest demonstrated integrated photonic crystal based laser cavities. The simulation shows a lasing threshold current density of 1kA/cm2 for a 300 nm outer diameter ring cavity with 80 nm-wide ring. This current density can be realistically achieved in typical III-V semiconductor, which shows the experimental feasibility of the proposed PSNRL structure.

Ultra-compact multilayer Si/SiO 2 GRIN lens mode-size converter for coupling single-mode fiber to Si-wire waveguide

We report on the fabrication and experimental demonstration of optical mode size transformation between standard single-mode fiber and 0.26 μm-thick Si-waveguide by 12 μm-thick Si/SiO(2) multilayer on-chip GRIN lens of lengths 16 μm or 24 μm butt-joint to 10 μm-wide terminated Si-waveguide. The overall coupling loss of the coupler was measured to be 3.45 dB in which the Fresnel reflection loss is estimated to be 2dB at the GRIN-lens/air interface. The on-chip integrated GRIN lens opens up the feasibility of a low cost passive aligned fiber-pigtailed electronic-photonics integrated circuits platform.

Electrically pumped heterogeneously integrated Si/III-V evanescent lasers with micro-loop mirror reflector

An electrically pumped heterogeneously integrated Si/AlGaInAs evanescent laser with micro-loop mirror (MLM) as high reflectors at both ends is experimentally demonstrated. Finite-difference time-domain simulation shows that 98% reflectivity can be achieved with micro-loop mirror formed by single-mode silicon-on-insulator (SOI) waveguides. The laser based on a Si/III-V hybrid gain waveguide and passive SOI MLM reflectors is fabricated and single-mode continuous-wave (CW) lasing is achieved at room temperature with a lasing threshold current density of 2.5 kA/cm2.

Electro-optic modulator with exceptional power-size performance enabled by transparent conducting electrodes.

An EO phase modulator having transparent conducting oxide electrodes and an inverted rib waveguide structure is demonstrated. This new modulator geometry employs an EO polymer having an in-device r33 = 60pm/V. The measured half-wave voltage Vpi of these devices ranges from 5.3V to 11.2V for 3.8 and 1.5 mm long devices, respectively. The lowest VpiL figure-of-merit corresponds to 0.6V-cm (7.2mW-cm(2) of power length product) in a dual-drive configuration. The trade-off between Vpi, insertion loss and modulation bandwidth is systematically analyzed. An optimized high-speed structure is proposed, with numerical simulation showing that this new structure and an in-device r33 = 150pm/V, can achieve Vpi = 0.5V in a 5mm long active length with dual drive operation. The insertion loss is targeted at 6dB, and a 3dB optical modulation bandwidth can reach > 40GHz.

High-speed low-power photonic transistor devices based on optically-controlled gain or absorption to affect optical interference

We show that a photonic transistor device can be realized via the manipulation of optical interference by optically controlled gain or absorption in novel ways, resulting in efficient transistor signal gain and switching action. Exemplary devices illustrate two complementary device types with high operating speed, microm size, microW switching power, and switching gain. They can act in tandem to provide a wide variety of operations including wavelength conversion, pulse regeneration, and logical operations. These devices could have a Transistor Figure-of-Merits >10(5) times higher than current chi((3)) approaches and are highly attractive.

Paramagnetic resonance of platinum ions in PbTiO3 single crystals

Optical excitation of trivalent platinum (5d7, t6e) ions in lead titanate single crystals have been observed for the first time by electron paramagnetic resonance (EPR). The g and hyperfine coupling A tensors were found to be axial: g∥=1.938, g⊥=2.478, A∥=0.0164 cm−1, and A⊥=0.0324 cm−1. Analysis of the EPR spectra using crystal field theory indicates that the Pt+3 ions are in tetragonally distorted (elongated) octahedral sites, strongly suggesting that they substitute for the central Ti+4 ions in the perovskite lattice.

Light Energy Extraction From the Minor Surface Arc of an Electrically Pumped Elliptical Microcavity Laser

In this paper, the efficiency of extracting light energy from the minor surface arc of the elliptical microcavity laser is investigated for the first time using the dynamic thermal electron quantum medium finite-difference time-domain model. Light energy is extracted from the minor surface arc of the elliptical microcavity to a perpendicular waveguide. It is deduced from the field distribution that extraction efficiency of the TM polarization is higher due to wider transverse field profile. Optimum light energy is extracted when the waveguide is 0.342 ¿m away from the edge of the elliptical minor arc. Higher extraction efficiency is also obtained when the waveguide index is lower than the microcavity index. It is believed that this method of extracting light energy allows for smaller device size with higher power output for building photonic integrated circuit.