Liangliang Wang

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.

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.

Crosstalk analysis of silicon-on-insulator nanowire-arrayed waveguide grating*

The factors influencing the crosstalk of silicon-on-insulator (SOI) nanowire arrayed waveguide grating (AWG) are analyzed using the transfer function method. The analysis shows that wider and thicker arrayed waveguides, outsider fracture of arrayed waveguide, and larger channel space, could mitigate the deterioration of crosstalk. The SOI nanowire AWGs with different arrayed waveguide widths are fabricated by using deep ultraviolet lithography (DUV) and inductively coupled plasma etching (ICP) technology. The measurement results show that the crosstalk performance is improved by about 7 dB through adopting 800 nm arrayed waveguide width.

High-Duty-Cycle Operation of GaAs/AlGaAs Quantum Cascade Laser above Liquid Nitrogen Temperature

We present a detailed study of lambda similar to 9.75 mu m GaAs/AIGaAs quantum cascade lasers. For a coated 2-mm-long and 40-mu m-wide laser, an optical power of 85 mu W is observed 95% duty cycle at 80 K. At a moderate driving pulse (1 kHz and 1% duty cycle), the device presents a peak power more than 20 mW even at 120 K. At 80 K, the fitted result of threshold current densities shows evidence of potential cw operation.