Xiongwei Hu

Light Emission Enhancement From Er-Doped Silicon Photonic Crystal Double-Heterostructure Microcavity

We experimentally demonstrate efficient light emission enhancement from Si with Er/O co-implanting coupled to 2-D hexagonal photonic crystal (PC) double-heterostructure microcavity fabricated on silicon-on-insulator. A single sharp resonant peak with 1552.2 nm communication wavelength dominates the photoluminescence (PL) spectrum and 35-fold PL intensity enhancement is obtained compared to the case of identically implanted silicon-on-insulator wafer at room temperature. The obvious red-shift and degraded Q-factor of resonant peak are present with the excitation power increasing, and the maximum measured Q-factor of 3829 is found at 1.5 mW power. The resonant peak is observed to shift depending on the structural parameters of PC.

Design and Fabrication of Novel Symmetric Low-Loss 1 × 24 Optical Power Splitter

In this paper, a three-branch structure with different output widths, broadening, and transition waveguide are discussed in detail. Based on the three-branch structure, a compact, low-loss, and good uniformity 1 × 24 optical power splitter is designed and fabricated using silica-based PLC technology on quartz substrate. The measurement results show that the insertion loss, the uniformity, wavelength-dependence loss of the splitter are less than 14.8, 0.92, and 0.93 dB, respectively, in the wavelength range from 1.25 to 1.65 μm. The polarization dependence loss is less than 0.16 dB in the wavelength of 1.27, 1.31, 1.49, 1.55, and 1.625 μm.

Tunable filters based on an SOI nano-wire waveguide micro ring resonator

Micro ring resonator (MRR) filters based on a silicon on insulator (SOI) nanowire waveguide are fabricated by electron beam photolithography (EBL) and inductive coupled plasma (ICP) etching technology. The cross-section size of the strip waveguides is 450 × 220 nm2, and the bending radius of the micro ring is around 5 μm. The test results from the tunable filter based on a single ring show that the free spectral range (FSR) is 16.8 nm and the extinction ratio (ER) around the wavelength 1550 nm is 18.1 dB. After thermal tuning, the filters tuning bandwidth reaches 4.8 nm with a tuning efficiency of 0.12 nm/°C Meanwhile, we fabricated and studied multi-channel filters based on a single ring and a double ring. After measurement, we drew the following conclusions: during the signal transmission of multi-channel filters, crosstalk exists mainly among different transmission channels and are fairly distinct when there are signals input to add ports.

Novel triplexing-filter design using silica-based direction coupler and an arrayed waveguide grating

A new triplexing filter based on a silica direction coupler and an arrayed waveguide grating is presented. Using a combination of a direction coupler and an arrayed waveguide grating, a 1310-nm channel is multiplexed and 1490- and 1550-nm channels are demultiplexed for fiber-to-the-home. The direction coupler is used to coarsely separate the 1310-nm channel from the 1490- and 1550-nm channels. Subsequently, an arrayed waveguide grating is used to demultiplex the 1490- from 1550-nm channel. The simulated spectra show the 1-dB bandwidth of 110 nm for the 1310-nm channel and 20 and 20.5 nm for the 1490- and 1550-nm channels. The insertion loss is only 0.15 dB for 1310 nm and 5 dB for 1490 and 1550 nm. The crosstalk between the 1490- and 1550-nm channels was less than -35 dB

Novel wavelength-accurate InP-based arrayed waveguide grating

A 13-channel, InP-based arrayed waveguide grating (AWG) is designed and fabricated in which the on-chip loss of the central channel is about −5 dB and the crosstalk is less than −23 dB in the center of the spectrum response. However, the central wavelength and channel spacing are deviated from the design values. To improve their accuracy, an optimized design is adopted to compensate the process error. As a result, the central wavelength 1549.9 nm and channel spacing 1.59 nm are obtained in the experiment, while their design values are 1549.32 nm and 1.6 nm, respectively. The route capability and thermo–optic characteristic of the AWG are also discussed in detail.

Design and fabrication of an InP arrayed waveguide grating for monolithic PICs

A 10-channel, 200 GHz channel spacing InP arrayed waveguide grating was designed, and the deep ridge waveguide design makes it polarization independent. Under the technologies of molecular beam epitaxy, lithography, and induced coupler plasma etching, the chip was fabricated in our laboratory. The test results show that the insertion loss is about −8 dB, and the crosstalk is less than −17 dB.

Low power consumption 4-channel variable optical attenuator array based on planar lightwave circuit technique*

The power consumption of a variable optical attenuator (VOA) array based on a silica planar lightwave circuit was investigated. The thermal field profile of the device was optimized using the finite-element analysis. The simulation results showed that the power consumption reduces as the depth of the heat-insulating grooves is deeper, the up-cladding is thinner, the down-cladding is thicker, and the width of the cladding ridge is narrower. The materials component and thickness of the electrodes were also optimized to guarantee the driving voltage under 5 V. The power consumption was successfully reduced to as low as 155 mW at an attenuation of 30 dB in the experiment.

16 channel 200 GHz arrayed waveguide grating based on Si nanowire waveguides

A 16 channel arrayed waveguide grating demultiplexer with 200 GHz channel spacing based on Si nanowire waveguides is designed. The transmission spectra response simulated by transmission function method shows that the device has channel spacing of 1.6 nm and crosstalk of 31 dB. The device is fabricated by 193 nm deep UV lithography in silicon-on-substrate. The demultiplexing characteristics are observed with crosstalk of 5–8 dB, central channels insertion loss of 2.2 dB, free spectral range of 24.7 nm and average channel spacing of 1.475 nm. The cause of the spectral distortion is analyzed specifically.

Light extraction enhancement of SOI-based erbium/oxygen Co-implanted photonic crystal microcavities

H5 photonic crystal (PC) microcavities co-implanted with erbium (Er) and oxygen (O) ions were fabricated on silicon-on-insulator (SOI) wafers. Photoluminescence (PL) measurements were taken at room temperature and a light extraction enhancement of up to 12 was obtained at 1.54 μm, as compared to an identically implanted unpatterned SOI wafer. In addition, we also explored the adjustment of cavity modes by changing the structural parameters of the PC, and the measured results showed that the cavity-resonant peaks shifted towards shorter wavelengths as the radius of the air holes increased, which is consistent with the theoretical simulation.

Fabrication of a novel silica PLC hybrid integrated triplexer

A new-style silica planar lightwave circuit (PLC) hybrid integrated triplexer, which can demultiplex 1490-nm download data and 1550-nm download analog signals, as well as transmit 1310-nm upload data, is presented. It combines SiO2 arrayed waveguide gratings (AWGs) with integrated photodetectors (PDs) and a high performance laser diode (LD). The SiO2 AWGs realize the three-wavelength coarse wavelength-division multiplexing (CWDM). The crosstalk is less than 40 dB between the 1490- and 1550-nm channels, and less than 45 dB between 1310- and 1490- or 1550-nm channels. For the static performances of the integrated triplexer, its upload output power is 0.4 mW, and the download output photo-generated current is 76 A. In the small-signal measurement, the upstream 3-dB bandwidth of the triplexer is 4 GHz, while the downstream 3-dB bandwidths of both the analog and digital sections reach 1.9 GHz.