Published papers

A light source based on single-walled carbon nanotubes (SWNTs) is one of the promising candidates for a microsized light source on a silicon chip at telecommunication wavelengths in optical communications and optical interconnects. However, SWNT-based light emitters possess the disadvantage of having a very broad emission spectrum. Here, we present an ultranarrow-linewidth photoluminescence (PL) emitter based on a silica toroid resonator, along with SWNTs, on a silicon chip. We simultaneously managed both excitation and emission lights at telecommunication wavelengths on a silicon chip by employing a very simple in-line configuration consisting of a toroid resonator and a tapered fiber for light input and output. Owing to the extremely high Q factor of our silica toroid resonator, we obtained an ultrahigh Q factor (∼2.1 × 104) of C-band PL emission. We also demonstrated strong PL emission under laterally polarized excitation conditions owing to the strong coupling to the toroid resonator, and laterally polarized PL emission can be selectively generated independently of the excitation polarization direction. This SWNT-based PL emitter based on a simple system with a silica toroid resonator can open routes to highly integrated photonics and optoelectronics on silicon-based platforms.

We present a compact silicon photonic crystal spectrometer with a footprint of 740 × 9 μm2 and excellent wavelength resolution (∼0.01 nm at single and <0.03 nm at multiple wavelength operation) across a telecom bandwidth of 10 nm. Although our design targets a wavelength resolution of 1.6 nm, within the current state-of-the-art fabrication precision of 2 nm, we achieve a resolution that exceeds these limits. This enhanced resolution is made possible by leveraging the random localization of light within the device.

Ultrahigh repetition rate lasers will become vital light sources for many technologies; however, they are difficult to realize because the cavity must be miniaturized. A mode-locked laser with whispering-gallery-mode (WGM) microresonators would provide a cost-effective on-chip solution that would allow us to demonstrate ultra-high repetition rate lasers. However, the required parameters, such as the cavity size, dispersion, minimum gain, and amount of saturable absorption (SA) loss, are unknown; we need to establish a clear guideline if we wish to discuss experimental feasibility and achieve mode locking (ML). Here, we report on a numerical investigation that clarified the optimum design parameters to achieve passive ML with a toroidal WGM microlaser.

We numerically investigate the deterministic generation of a perfect soliton crystal (PSC) in an optical microresonator functionalized with a saturable absorber (SA). The SAallows the direct formation of a PSC from an initial, periodic Turing roll. It prevents passage through a chaotic state, which induces a stochastic nature with regard to the number of generated dissipativeKerr solitons.We showthat PSCs form deterministically, and the number is controlled by adjusting the input power and SA parameter. Our work provides a simple approach for obtaining a stable PSC that offers an ultrahigh repetition rate and a high comb output power.

We found that we can deterministically generate a perfect soliton crystal by incorporating a saturable absorber in a microresonator. The crystal is generated directly from the initial Turing rolls without passing through chaos.

We found that we can deterministically generate a perfect soliton crystal by incorporating a saturable absorber in a microresonator. The crystal is generated directly from the initial Turing rolls without passing through chaos.

We investigated the pump effective detuning dependence of noise and linewidth characteristics of modulation instability combs. Modulation instability combs are useful for applications if the detuning is smaller than several times the resonace linewidth.

We investigated the pump effective detuning dependence of noise and linewidth characteristics of modulation instability combs. Modulation instability combs are useful for applications if the detuning is smaller than several times the resonace linewidth.