Enhancing Si3N4 Waveguide Nonlinearity with Heterogeneous Integration of Few-Layer WS2.
TL;DR: In this article, a few-layer WS2 flake of ∼14.8 μm length was transferred to a dispersion-engineered silicon nitride waveguide and an effective nonlinear coefficient higher than 600 m-1 W-1 was retrieved for the heterogeneous waveguide indicating an enhancement factor of larger than 300 with respect to the pristine waveguide at a wavelength of 800 nm.
Abstract: The heterogeneous integration of low-dimensional materials with photonic waveguides has spurred wide research interest. Here, we report on the experimental investigation and the numerical modeling of enhanced nonlinear pulse broadening in silicon nitride waveguides with the heterogeneous integration of few-layer WS2. After transferring a few-layer WS2 flake of ∼14.8 μm length, the pulse spectral broadening in a dispersion-engineered silicon nitride waveguide has been enhanced by ∼48.8% in bandwidth. Through numerical modeling, an effective nonlinear coefficient higher than 600 m-1 W-1 has been retrieved for the heterogeneous waveguide indicating an enhancement factor of larger than 300 with respect to the pristine waveguide at a wavelength of 800 nm. With further advances in two-dimensional material fabrication and integration techniques, on-chip heterostructures will offer another degree of freedom for waveguide engineering, enabling high-performance nonlinear optical devices, such as frequency combs and quantum light sources.
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TL;DR: In this article , a solution-based transfer-free coating method was used to integrate two-dimensional (2D) graphene oxide (GO) films onto the SOI nanowires with precise control of the film thickness.
Abstract: We experimentally demonstrate enhanced spectral broadening of femtosecond optical pulses after propagation through silicon-on-insulator (SOI) nanowire waveguides integrated with two-dimensional (2D) graphene oxide (GO) films. Owing to the strong mode overlap between the SOI nanowires and the GO films with a high Kerr nonlinearity, the self-phase modulation (SPM) process in the hybrid waveguides is significantly enhanced, resulting in greatly improved spectral broadening of the femtosecond optical pulses. A solution-based, transfer-free coating method is used to integrate GO films onto the SOI nanowires with precise control of the film thickness. Detailed SPM measurements using femtosecond optical pulses are carried out, achieving a broadening factor of up to ~4.3 for a device with 0.4-mm-long, 2 layers of GO. By fitting the experimental results with the theory, we obtain an improvement in the waveguide nonlinear parameter by a factor of ~3.5 and in the effective nonlinear figure of merit (FOM) by a factor of ~3.8, relative to the uncoated waveguide. Finally, we discuss the influence of GO film length on the spectral broadening and compare the nonlinear optical performance of different integrated waveguides coated with GO films. These results confirm the improved nonlinear optical performance of silicon devices integrated with 2D GO films.
15 citations
TL;DR: In this article , the authors demonstrate enhanced self-phase modulation (SPM) in silicon nitride (Si3N4) waveguides integrated with 2D graphene oxide (GO) films using a solution-based, transfer-free coating method that enables precise control of the film thickness.
Abstract: We experimentally demonstrate enhanced self-phase modulation (SPM) in silicon nitride (Si3N4) waveguides integrated with 2D graphene oxide (GO) films. GO films are integrated onto Si3N4 waveguides using a solution-based, transfer-free coating method that enables precise control of the film thickness. Detailed SPM measurements are carried out using both picosecond and femtosecond optical pulses. Owing to the high Kerr nonlinearity of GO, the hybrid waveguides show significantly improved spectral broadening compared to the uncoated waveguide, achieving a broadening factor of up to ~3.4 for a device with 2 layers of GO. By fitting the experimental results with theory, we obtain an improvement in the waveguide nonlinear parameter by a factor of up to 18.4 and a Kerr coefficient (n2) of GO that is about 5 orders of magnitude higher than Si3N4. Finally, we provide a theoretical analysis for the influence of GO film length, coating position, and its saturable absorption on the SPM performance. These results verify the effectiveness of on-chip integrating 2D GO films to enhance the nonlinear optical performance of Si3N4 devices.
12 citations
TL;DR: In this article , the applications of graphene oxide to nonlinear integrated photonic devices are reviewed, followed by comparisons of the nonlinear optical performance of different integrated platforms incorporating GO as well as hybrid integrated devices including different kinds of 2D materials.
Abstract: Integrated photonic devices operating via optical nonlinearities offer a powerful solution for all‐optical information processing, yielding processing speeds that are well beyond that of electronic processing as well as providing the added benefits of compact footprint, high stability, high scalability, and small power consumption. The increasing demand for high‐performance nonlinear integrated photonic devices has facilitated the hybrid integration of novel materials to address the limitations of existing integrated photonic platforms. Recently, graphene oxide (GO), with its large optical nonlinearity, high flexibility in altering its properties, and facile fabrication processes, has attracted significant attention, enabling many hybrid nonlinear integrated photonic devices with improved performance and novel capabilities. This paper reviews the applications of GO to nonlinear integrated photonics. First, an overview of GO's optical properties and the fabrication technologies needed for its on‐chip integration is provided. Next, the state‐of‐the‐art GO nonlinear integrated photonic devices are reviewed, followed by comparisons of the nonlinear optical performance of different integrated platforms incorporating GO as well as hybrid integrated devices including different kinds of 2D materials. Finally, the current challenges and future opportunities in this field are discussed.
8 citations
TL;DR: In this article , low-loss silicon photonic spiral waveguides beyond the single-mode regime are proposed and demonstrated for realizing an enhanced four-wave mixing (FWM) process.
Abstract: Low-loss optical waveguides are highly desired for nonlinear photonics such as four-wave mixing (FWM), optical parametric amplification, and pulse shaping. In this work, low-loss silicon photonic spiral waveguides beyond the single-mode regime are proposed and demonstrated for realizing an enhanced FWM process. In particular, the designed 2-µm-wide silicon photonic waveguides are fabricated with standard foundry processes and have a propagation loss as low as ∼0.28 dB/cm due to the reduced light-matter interaction at the waveguide sidewalls. In the experiments, strong FWM effect is achieved with a high conversion efficiency of -8.52 dB in a 2-µm-wide and 20-cm-long silicon photonic waveguide spiral, and eight new wavelengths are generated with the pump power of ∼80 mW (corresponding to a low power density of ∼195 mW/µm2). In contrast, the FWM efficiency for the 0.45-µm-wide waveguide spiral is around -15.4 dB, which is much lower than that for the 2-µm-wide waveguide spiral. It can be seen that silicon photonics beyond the singlemode regime opens a new avenue for on-chip nonlinear photonics and will bring new opportunities for nonlinear photonic applications.
2 citations
TL;DR: In this article , a huge spectral broadening of a femtosecond laser pulse after propagation through a very thin one-dimensional (1D) metal-dielectric (MD) photonic structure is reported.
1 citations
References
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TL;DR: In this paper, the index of refraction of optical quality fused silica (SiO2) was determined for 60 wavelengths from 0.21 to 3.71 μ at 20°C.
Abstract: The index of refraction of optical quality fused silica (SiO2) was determined for 60 wavelengths from 0.21 to 3.71 μ at 20°C. The dispersion equation n2-1=0.6961663λ2λ2-(0.0684043)2+0.4079426λ2λ2-(0.1162414)2+0.8974794λ2λ2-(9.896161)2.where λ is expressed in microns was found to yield an absolute residual of 10.5×10−6. The variation in index between 12 specimens was determined. Dispersive properties of the material and thermal coefficient of index are graphically presented. A comparison with previous NBS index data is discussed.
3,382 citations
04 Oct 2006
TL;DR: In this paper, a 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.
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.
3,361 citations
TL;DR: In this article, a review of nonlinear effects in silicon and highlights the important applications and technological solutions in nonlinear silicon photonics is presented. But the authors do not discuss the nonlinearities in silicon.
Abstract: The nonlinearities in silicon are diverse. This Review covers the wealth of nonlinear effects in silicon and highlights the important applications and technological solutions in nonlinear silicon photonics. The increasing capability for manufacturing a wide variety of optoelectronic devices from polymer and polymer–silicon hybrids, including transmission fibre, modulators, detectors and light sources, suggests that organic photonics has a promising future in communications and other applications.
1,123 citations
TL;DR: In this paper, the complex in-plane dielectric function from 1.5 to 3 eV for monolayers of four transition metal dichalcogenides (MoSe 2, WSe2, MoS2, and WS2) was presented.
Abstract: This chapter presents the complex in-plane dielectric function from 1.5 to 3 eV for monolayers of four transition metal dichalcogenides: MoSe2, WSe2, MoS2, and WS2. The results were obtained from optical reflection spectra using a Kramers–Kronig constrained variational analysis. From the inferred dielectric functions, we obtain the absolute absorbance of the monolayers. We also provide a comparison of the dielectric function for the monolayers with the respective bulk materials [1].
1,080 citations
TL;DR: In this paper, a review of the developments in the emerging and rapidly advancing field of atomic and molecular broadband spectroscopy with frequency combs is presented. But this review is limited to the use of laser frequency combers.
Abstract: A laser frequency comb is a broad spectrum composed of equidistant narrow lines. Initially invented for frequency metrology, such combs enable new approaches to spectroscopy over broad spectral bandwidths, of particular relevance to molecules. The performance of existing spectrometers — such as crossed dispersers employing, for example, virtual imaging phase array etalons, or Michelson-based Fourier transform interferometers — can be dramatically enhanced with optical frequency combs. A new class of instruments, such as dual-comb spectrometers without moving parts, enables fast and accurate measurements over broad spectral ranges. The direct self-calibration of the frequency scale of the spectra within the accuracy of an atomic clock and the negligible contribution of the instrumental line-shape will enable determinations of all spectral parameters with high accuracy for stringent comparisons with theories in atomic and molecular physics. Chip-scale frequency comb spectrometers promise integrated devices for real-time sensing in analytical chemistry and biomedicine. This Review gives a summary of the developments in the emerging and rapidly advancing field of atomic and molecular broadband spectroscopy with frequency combs. Frequency comb spectroscopy is a recent field of research that has blossomed in the past five years. This Review discusses developments in the emerging and rapidly advancing field of atomic and molecular broadband spectroscopy with frequency combs.
576 citations