News
[2024/03/20] Our paper was published in Optics Express
We report a Ta2O5 photonic platform with a propagation loss of 0.49 dB/cm at 1550 nm, of 0.86 dB/cm at 780 nm, and of 3.76 dB/cm at 2000 nm. The thermal bistability measurement is conducted in the entire C-band for the first time to reveal the absorption loss of Ta2O5 waveguides, offering guidelines for further reduction of the waveguide loss. We also characterize the Ta2O5 waveguide temperature response, which shows favorable thermal stability. The fabrication process temperature is below 350°C, which is friendly to integration with active optoelectronic components.
The paper can be accessed on Optics Express website.
[2024/02/17] Our paper was accepted in the 2024 CLEO Conference
We report a GaP-OI resonator with a Q factor of (2.3±0.3)×104 and a TDWS of 53.9 pm/K, which shows great promise of the GaP-OI platform in thermal turning and optical signal processing.
Congratulations to Weiren Cheng! The 2024 CLEO Conference website can be accessed here.
[2024/02/13] Our paper was published in IEEE Photonics Journal
We describe a synergistic optimization approach that enables highly efficient frequency translation of a Kerr optical frequency comb (OFC) from 1550 nm to 775 nm in a gallium phosphide-on-insulator (GaP-OI) microresonator. Key distinctions from previous GaP-OI works which focused on individual optical nonlinearity are that this work not only emphasizes the interaction between the second- and third-order nonlinearity, but also explores the tunability of the χ(2)-translated OFC through geometric and temperature tuning. The sum-frequency (SF) comb at 775 nm has a geometric tuning sensitivity of 354 GHz/nm, and a thermal tuning sensitivity of 24.8 GHz/K, paving the way for post-fabrication trimming and in-situ spectral shaping, with a broader potential to realize highly efficient, wide-spectrum, and tunable on-chip nonlinear sources.
The paper can be accessed on IEEE Photonics Journal website.
[2023/12/19] Our paper was accepted in the 2024 OFC Conference
We demonstrate a Ta2O5 photonic platform with a propagation loss of 0.5dB/cm and a thermo-optic coefficient of 2.3×10-6 /K at 1550 nm. The process temperature is below 350℃, friendly to integration with other optoelectronic components.
Congratulations to Zhaoting Geng! The 2024 OFC Conference website can be accessed here.
[2023/07/12] Our paper was published in Optics Letters
We report a gallium phosphide-on-insulator (GaP-OI) photonic platform fabricated by an intermediate-layer bonding process aiming to increase the manufacture scalability in a low-cost manner. This is enabled by the "etch-n-transfer" sequence, which results in inverted rib waveguide structures. The shallow-etched 1.8 μm-wide waveguide has a propagation loss of 23.5 dB/cm at 1550 nm wavelength. Supercontinuum generation based on the self-phase modulation effect is observed when the waveguides are pumped by femtosecond pulses. The nonlinear refractive index of GaP, n2, is extracted to be 1.9×10-17 m2/W, demonstrating the great promise of the GaP-OI platform in third-order nonlinear applications.
The paper can be accessed on Optics Letters website.
[2023/07/07] Our paper was published in JOSA B
In this paper, we theoretically demonstrate two-color Kerr frequency combs generation in the GaP-OI platform using a single pump source. This is enabled by dispersion engineering on a partially etched coupled ring resonator whose anomalous dispersion is wide enough to support Kerr frequency comb generation at both 3100 nm and 1550 nm wavelengths. The pump source at 1550 nm is realized through frequency doubling of the 3100 nm light in a GaP-OI straight waveguide. Compared with other cascaded second- and third-order nonlinear processes, the proposed approach can reach high-power and wide-bandwidth combs at both SWIR and MIR regions.
The paper can be accessed on JOSA B website.
[2022/06/30] Call for Papers! The "Integrated Waveguide-Based Photonic Devices" special issue is now open for submission!
This Special Issue focuses on the state-of-the-art achievements in integrated waveguide-based photonic devices, with a broader aim to present novel material, design methodology, and fabrication techniques as well as cutting-edge applications.
The submission deadline is June 30, 2023. More submission information can be found here.
RESEARCH
Nonlinear integrated photonic devices
Nonlinear integrated photonics plays important roles in optical communications, sensing, spectroscopy, etc. Numerous nonlinear devices such as light sources, modulators, and sensors have been demonstrated thanks to the rich optical nonlinear mechanisms. Miniaturization of the photonic devices not only reduces the cost but also makes complex systems suitable for portable and field deployed applications. On-chip photonic integration is an enabling factor to miniaturize nonlinear optical devices. With the development of highly nonlinear photonic integration platform, novel on-chip nonlinear devices will emerge with unprecedent performance, and will find useful in quantum photonics, machine learning, optical neuron computing and other leading-edge applications.
Our group will focus on the frequency comb generation, second harmonic generation, supercontinuum generation and related nonlinear phenomena in the emerging gallium phosphide-on-insulator platform.
On-chip optical reference cavities
Optical reference cavities are essential components in laser linewidth narrowing and frequency stabilization. Once tightly locked to a frequency reference, the frequency stability of the laser is determined by the stability of the cavity. Traditional benchtop Fabry-Perot reference cavities occupy a large operation space. It is desirable to miniaturize these cavities harnessing the photonic integrated waveguide-based technologies, which may foster a blossom of integrated narrow linewidth lasers.
Our group study the frequency stability of on-chip microresonators and their applications in laser frequency locking. The research topics cover the athermal waveguides, high-Q resonators, frequency locking systems, temperature sensing techniques, and related areas.
Silicon nitride photonic devices
Silicon nitride is a versatile photonic material that is compatible with silicon photonics. It has moderate refractive index, low propagation loss, non-negligible third-order nonlinearity, and thus is widely used in passive photonic devices for optical interconnecting, optical nonlinear, bio-photonic applications. Integrating functional components empowers silicon nitride passive devices unprecedented functionalities that could only be realized in active photonic devices, such as modulators, detectors, etc., opening new possibilities for a whole new class of integrated devices and systems.
Our group has rich experience in nanowire-incorporated silicon nitride waveguide devices, such as optical leaky wave antennas and plasmo-thermomechanical radiation detectors. We are working on silicon nitride equivalent materials to establish a new photonic integration platform.
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