Ultra-flat dispersion in an integrated waveguide with five and six zero-dispersion wavelengths for mid-infrared photonics

We propose a new type of dispersion flattening technology, which can generate an ultra-flat group velocity dispersion profile with five and six zero-dispersion wavelengths(ZDWs). The dispersion value varies from-0.15 to 0.35 ps/(nm·km) from 4 to 8 μm, which to the best of our knowledge is the flattest one reported so far, and the dispersion flatness is improved by more than an order of magnitude. We explain the principle of producing six ZDWs. Mode distribution in this waveguide is made stable over a wide bandwidth. General guidelines to systematically control the dispersion value, sign, and slope are provided, and one can achieve the desired dispersion by properly adjusting the structural parameters. Fabrication tolerance of this waveguide is also examined.

Broadband athermal waveguides and resonators for datacom and telecom applications

The high-temperature sensitivity of the silicon material index limits the applications of silicon-based micro-ring resonators in integrated photonics. To realize a low but broadband temperature-dependent-wavelength-shift microring resonator, designing a broadband athermal waveguide becomes a significant task. In this work,we propose a broadband athermal waveguide that shows a low effective thermo-optical coefficient of1 × 10^(-6)∕K from 1400 to 1700 nm. The proposed waveguide shows a low-loss performance and stable broadband athermal property when it is applied to ring resonators, and the bending loss of ring resonators with a radius of >30 μm is 0.02 dB/cm.

Robust cavity soliton formation with hybrid dispersion

Microresonator-based Kerr frequency combs have attracted a great deal of attention in recent years, in which mode locking of the generated combs is associated with bright or dark cavity soliton formation. In this paper,we show that, different from soliton propagation along a waveguide, cavity solitons can be robustly formed under a unique dispersion profile with four zero-dispersion wavelengths. More importantly, such a dispersion profile exhibits much smaller overall dispersion, thus making it possible to greatly reduce the pump power by five to six times.

High spectro-temporal compression on a nonlinear CMOS-chip

Optical pulses are fundamentally defined by their temporal and spectral properties.The ability to control pulse properties allows practitioners to efficiently leverage them for advanced metrology,high speed optical communications and attosecond science.Here,we report 11×temporal compression of 5.8 ps pulses to 0.55 ps using a low power of 13.3 W.The result is accompanied by a significant increase in the pulse peak power by 9.4×.These results represent the strongest temporal compression demonstrated to date on a complementary metal–oxide–semiconductor(CMOS)chip.In addition,we report the first demonstration of on-chip spectral compression,3.0×spectral compression of 480 fs pulses,importantly while preserving the pulse energy.The strong compression achieved at low powers harnesses advanced on-chip device design,and the strong nonlinear properties of backend-CMOS compatible ultra-silicon-rich nitride,which possesses absence of two-photon absorption and 500×larger nonlinear parameter than in stoichiometric silicon nitride waveguides.The demonstrated work introduces an important new paradigm for spectro-temporal compression of optical pulses toward turn-key,on-chip integrated systems for all-optical pulse control.

Robust generation of frequency combs in a microresonator with strong and narrowband loss

Octave-spanning frequency comb generation in microresonators is promising, but strong spectral losses caused by material absorption and mode coupling between two polarizations or mode families can be detrimental. We examine the impact of the spectral loss and propose robust comb generation with a loss of even 300 dB/cm.Cavity nonlinear dynamics show that a phase change associated with spectral losses can facilitate phase matching and Kerr comb generation. Given this unique capability, we propose a novel architecture of on-chip spectroscopy systems.