Lianyan Li

Bio: Lianyan Li is an academic researcher from Nanjing University. The author has contributed to research in topics: Laser & Distributed feedback laser. The author has an hindex of 10, co-authored 30 publications receiving 414 citations. Previous affiliations of Lianyan Li include Ghent University.

III-V-on-Silicon Photonic Devices for Optical Communication and Sensing

Abstract: In the paper, we review our work on heterogeneous III-V-on-silicon photonic components and circuits for applications in optical communication and sensing. We elaborate on the integration strategy and describe a broad range of devices realized on this platform covering a wavelength range from 850 nm to 3.85 μm.

High channel count and high precision channel spacing multi-wavelength laser array for future PICs.

Abstract: Multi-wavelength semiconductor laser arrays (MLAs) have wide applications in wavelength multiplexing division (WDM) networks. In spite of their tremendous potential, adoption of the MLA has been hampered by a number of issues, particularly wavelength precision and fabrication cost. In this paper, we report high channel count MLAs in which the wavelengths of each channel can be determined precisely through low-cost standard μm-level photolithography/holographic lithography and the reconstruction-equivalent-chirp (REC) technique. 60-wavelength MLAs with good wavelength spacing uniformity have been demonstrated experimentally, in which nearly 83% lasers are within a wavelength deviation of ±0.20 nm, corresponding to a tolerance of ±0.032 nm in the period pitch. As a result of employing the equivalent phase shift technique, the single longitudinal mode (SLM) yield is nearly 100%, while the theoretical yield of standard DFB lasers is only around 33.3%.

Study of the Multiwavelength DFB Semiconductor Laser Array Based on the Reconstruction-Equivalent-Chirp Technique

Abstract: A detailed theoretical analysis of the lasing wavelength precision of the DFB laser array based on a reconstruction-equivalent-chirp (REC) technique is presented. Experimental results of the eight-wavelength DFB laser array with equivalent π phase shift (π-EPS) and four-wavelength DFB laser array with equivalent three shifts are also given. High lasing wavelength precision was obtained. This paper demonstrates that the REC technique is a promising way for fabricating the multiwavelength DFB laser array with low cost and high yield.

On-chip mode converter based on two cascaded Bragg gratings.

Abstract: We propose an on-chip mode converter via two cascaded Bragg reflection processes. A forward conversion between two guided modes can be achieved with the aid of an additional mode. The proposed structure is theoretically studied and simulated via the rigorous three-dimensional finite-difference time-domain (3D-FDTD) method. The bandwidth and central wavelength of the proposed mode converter can be adjusted according to our theoretical analysis and simulation results. By applying the similar design approaches as fiber Bragg gratings, conversion spectra with different shapes can be obtained. As an example, several mode converters with bandpass and sidelobe-reduced spectra are designed. We also investigate and verify the mode conversion by experiment. Therefore, the proposed method may pave a new path for the mode converters with desired conversion spectra.

Reflectionless Tilted Grating Couplers With Improved Coupling Efficiency Based on a Silicon Overlay

Abstract: Grating couplers are important photonic devices on a complementary metal-oxide-semiconductor compatible silicon-on-insulator platform to couple light between optical waveguides and free space optical components or fibers. In this letter, we report the combination of a tilted grating coupler design, which strongly suppresses the back-reflection for light incident on the grating coupler from a waveguide, and a silicon overlay locally deposited on top of the grating region, which enhances the coupling efficiency of the grating coupler, by means of simulation and experiment. The fabricated tilted focusing grating couplers with silicon overlay show a coupling efficiency of -2.2 dB in combination with a back-reflection of around -40 dB when excited from the silicon waveguide. The tilted design also provides an alternative approach to enhance the transmission of a grating coupler when the thickness of the Si overlay is not optimized.

Supercontinuum generation, photonic crystal fiber

Abstract: A topical review of numerical and experimental studies of supercontinuum generation in photonic crystal fiber is presented over the full range of experimentally reported parameters, from the femtosecond to the continuous-wave regime. Results from numerical simulations are used to discuss the temporal and spectral characteristics of the supercontinuum, and to interpret the physics of the underlying spectral broadening processes. Particular attention is given to the case of supercontinuum generation seeded by femtosecond pulses in the anomalous group velocity dispersion regime of photonic crystal fiber, where the processes of soliton fission, stimulated Raman scattering, and dispersive wave generation are reviewed in detail. The corresponding intensity and phase stability properties of the supercontinuum spectra generated under different conditions are also discussed.

Silicon Photonics Circuit Design: Methods, Tools and Challenges

Abstract: Silicon Photonics technology is rapidly maturing as a platform for larger-scale photonic circuits. As a result, the associated design methodologies are also evolving from componentoriented design to a more circuit-oriented design flow, that makes abstraction from the very detailed geometry and enables design on a larger scale. In this paper, we review the state of this emerging photonic circuit design flow and its synergies with electronic design automation (EDA). We cover the design flow from schematic capture, circuit simulation, layout and verification. We discuss the similarities and the differences between photonic and electronic design, and the challenges and opportunities that present themselves in the new photonic design landscape, such as variability analysis, photonic-electronic co-simulation and compact model definition. Silicon Photonics Circuit Design: Methods, Tools and

Silicon Photonic Biosensors Using Label-Free Detection.

Abstract: Thanks to advanced semiconductor microfabrication technology, chip-scale integration and miniaturization of lab-on-a-chip components, silicon-based optical biosensors have made significant progress for the purpose of point-of-care diagnosis In this review, we provide an overview of the state-of-the-art in evanescent field biosensing technologies including interferometer, microcavity, photonic crystal, and Bragg grating waveguide-based sensors Their sensing mechanisms and sensor performances, as well as real biomarkers for label-free detection, are exhibited and compared We also review the development of chip-level integration for lab-on-a-chip photonic sensing platforms, which consist of the optical sensing device, flow delivery system, optical input and readout equipment At last, some advanced system-level complementary metal-oxide semiconductor (CMOS) chip packaging examples are presented, indicating the commercialization potential for the low cost, high yield, portable biosensing platform leveraging CMOS processes

Expanding the Silicon Photonics Portfolio With Silicon Nitride Photonic Integrated Circuits

Abstract: The high index contrast silicon-on-insulator platform is the dominant CMOS compatible platform for photonic integration. The successful use of silicon photonic chips in optical communication applications has now paved the way for new areas where photonic chips can be applied. It is already emerging as a competing technology for sensing and spectroscopic applications. This increasing range of applications for silicon photonics instigates an interest in exploring new materials, as silicon-on-insulator has some drawbacks for these emerging applications, e.g., silicon is not transparent in the visible wavelength range. Silicon nitride is an alternate material platform. It has moderately high index contrast, and like silicon-on-insulator, it uses CMOS processes to manufacture photonic integrated circuits. In this paper, the advantages and challenges associated with these two material platforms are discussed. The case of dispersive spectrometers, which are widely used in various silicon photonic applications, is presented for these two material platforms.

Optically Pumped GeSn Microdisk Lasers on Si

Abstract: The strong correlation between advancing the performance of Si microelectronics and their demand of low power consumption requires new ways of data communication. Photonic circuits on Si are already highly developed except for an eligible on-chip laser source integrated monolithically. The recent demonstration of an optically pumped waveguide laser made from the Si-congruent GeSn alloy, monolithical laser integration has taken a big step forward on the way to an all-inclusive nanophotonic platform in CMOS. We present group IV microdisk lasers with significant improvements in lasing temperature and lasing threshold compared to the previously reported nonundercut Fabry–Perot type lasers. Lasing is observed up to 130 K with optical excitation density threshold of 220 kW/cm2 at 50 K. Additionally the influence of strain relaxation on the band structure of undercut resonators is discussed and allows the proof of laser emission for a just direct Ge0.915Sn0.085 alloy where Γ and L valleys have the same energies....