We investigated phase-noise characteristics of both a phase/intensity-modulated laser with 25-GHz mode spacing and mode-locked fiber carrier-envelope-offset (CEO) locking. As the separation from frequency continuous wave (CW) diode (LD) for seed light source increases, integrated phase noise each comb supercontinuum originating it increases same slope as function number. The dependence on number is much larger than CEO However, extremely lower that locking in region around CW LD. could be...

Abstract Broadband on-chip optical frequency combs (OFCs) are important for expanding the functionality of photonic integrated circuits. Here, we demonstrate a huge local nonlinearity enhancement using graphene. A waveguide is decorated with graphene by precisely manipulating graphene’s area and position. Our approach simultaneously achieves both an extremely efficient supercontinuum ultra-short pulse generation. With our graphene-decorated silicon (G-SWG), have achieved enhanced spectral...

Acoustically induced dressed states of long-lived erbium ions in a crystal are demonstrated. These formed by rapid modulation two-level systems via strain surface acoustic waves whose frequencies exceed the optical linewidth ion ensemble. Multiple sidebands and reduction their intensities appearing near evidence strong interaction between ions. This development allows for on-chip control paves way to highly coherent hybrid quantum with telecom photons, phonons, electrons.

We report a cascaded optical fiber link which connects laboratories in RIKEN, the University of Tokyo, and NTT within 100-km region using transfer light at 1397 nm, subharmonic Sr clock frequency. The multiple employing several laser repeater stations benefits from wide feedback bandwidth for noise compensation, allows constructing lattice networks based on master-slave configuration. developed planar lightwave circuits to significantly reduce interferometer improved stability. implemented...

We report the first demonstration of continuous-wave laser diode based 100-fs-class pulse lasers operating at a gigahertz repetition rate without mode-locking technique. describe performance 1-W, 120-fs optical train 1 GHz and 80-fs 250 MHz by using simple configuration. Sub-100-fs durations are achieved progressive expansion spectrum in self-phase modulation process an erbium-doped fibre amplifier. Our scheme can achieve continuously tunable range ± 20%, develop powerful tools for use...

Low-noise millimetre-wave signals are valuable for digital sampling systems, arbitrary waveform generation ultra-wideband communications, and coherent radar systems. However, the phase noise of widely used conventional signal generators (SGs) will increase as frequency increases. Our goal has been to improve commercially available SGs so that they provide a low-phase-noise with assistance from an electro-optics-modulator-based optical comb (EOM-OFC). Here, we show can be greatly reduced by...

We propose a method of supercontinuum light generation enhanced by multimode excitation in precisely dispersion-engineered deuterated SiN (SiN:D) waveguide. Although regularly designed SiN-based nonlinear optical waveguide exhibits anomalous dispersion with the fundamental and first-order operation, center-symmetric pumping at input edge has so far inhibited full potential nonlinearity materials. On basis numerical analysis simulation for SiN:D waveguide, we intentionally applied spatial...

We experimentally demonstrate that by longitudinally pumping 2 mm long molybdenum preformed plasma with high-intensity 475 fs duration laser pulse, a highly directive soft-x-ray at 18.9 nm wavelength is generated. The divergence of the beam evaluated to be submilliradian order, and only requires pump energy 150 mJ.

Proposed is an approach to achieving a carrier-envelope-offset (CEO)-locked frequency comb with 25 GHz mode spacing in the telecommunications wavelength region. To achieve approach, 250 fs laser pulse train at repetition rate was developed by intensity- and phase-modulating seed light emitted from continuous-wave diode propagating it through dispersive fibre. Using authors' tellurite photonics crystal fibre high-nonlinear coefficient, octave-spanning supercontinuum generation 1.5 µm band MHz...

We demonstrate that a 2f-to-3f self-referencing interferometer (SRI) becomes useful tool for stabilizing carrier-envelope offset frequency of an Er-doped fiber laser. A dual-pitch periodically poled lithium niobate (PPLN) ridge waveguide, consisting two monolithically integrated segments with different quasi-phase matching pitch sizes, allows us to generate third-harmonic light high efficiency. By using this device, we obtain 45-dB signal-to-noise ratio in 100-kHz bandwidth heterodyne beat...

We have achieved the simultaneous generation of a 2.6-octave-wide supercontinuum (SC) spectrum over 400-2500 nm and third-harmonic light solely by dispersion-controlled silicon-nitride waveguide (SiNW). To increase visible intensity SC component, we fabricated low-loss 5-mm-long deuterated SiNWs with spot-size converters low-temperature deposition. succeeded in measuring carrier-envelope-offset (CEO) signal 34-dB signal-to-noise ratio because this short SiNW provides large temporal overlap...

We demonstrate on-chip octave-spanning supercontinuum (SC) generation with a Si-wire waveguide (SWG). precisely controlled the SWG width so that group velocity becomes flat over wide wavelength range. By adjusting length, we could reduce optical losses due to two-photon absorption and pulse propagation. In addition, for efficient coupling between laser waveguide, fabricated two-step inverse taper at both ends of SWG. Using 600-nm-wide SWG, were able generate broadband SC spectrum wavelengths...

Integrated optical amplifiers are essential building blocks for emerging applications of large-scale and complex silicon photonic integrated circuits. Single-crystal erbium-incorporated rare-earth oxide thin films epitaxially grown on substrate could be a promising material candidate. Based the mechanism bound states in continuum, we have developed low-loss waveguide platform such materials. The waveguides formed by patterning nitride cap layer film silicon-on-insulator substrate. Low...

We performed time-resolved reflectivity measurements in p-type heavily doped Si under non-resonant excitation. A large contribution from anisotropic state-filling is observed, indicating that the lowered Fermi energy due to heavy doping enhances anisotropy hole distribution. The initial phase shift of coherent phonons induced by attributed

We report the stabilization of carrier-envelope offset (CEO) frequency an Er-doped fiber laser with a collinear 2f-to-3f self-referencing interferometer. The interferometer is implemented by dual-pitch periodically poled lithium niobate ridge waveguide two different quasi-phase matching pitch sizes. obtain 52-dB signal-to-noise ratio in 100-kHz resolution bandwidth heterodyne beat signal, which sufficient for stabilization. also demonstrate that geometry robust against environmental...

A midfringe locked interferometer with differential detection is proposed for non-contact optical sound measurement, and the equivalent noise level of approximately 0 dB SPL/Hz achieved. The method 30 lower than that a very recent laser Doppler vibrometer close to quarter-inch measurement microphone. locking stabilizes against slow environmental fluctuations enables acoustic signal directly from intensity. eliminates intensity noise, which dominant source in interferometers. constructed...

We demonstrate a carrier-envelope-offset (CEO)- locked frequency comb with 230-pJ fiber coupling pulse energy by using passively mode-locked Er-fiber amplifier laser. For the generation of an octave-bandwidth spectrum in highly nonlinear and second harmonic self-referenced interferometer lower energy, we use tellurite photonic crystal direct-bonded quasi-phasematched LiNbO3 ridge waveguide, respectively. Our method is feasible for locking CEO to obtain low-noise highaccuracy optical at...

Investigations have been performed on harmonic generation from solid-vacuum interfaces using a prepulse-free 2.2-ps 1054-nm laser pulse at maximum intensities of /spl sim/1/spl times/10/sup 15/ W/spl middot/cm/sup -2/. The were strongest for p-polarized pump and dropped to about 50% in the case s-polarized pumps. ratio I/sub 4w/I/sub 2w/ between fourth second harmonics was 0.25 I/spl lambda//sup 2/=6/spl 14/ -2//spl middot//spl mu/m/sup 2/, which is relatively large when compared with value...

We investigated ultrafast carrier and phonon dynamics in semi-insulated (SI) n-type 4H-SiC using time-resolved reflectivity measurements. In the 4H-SiC, carriers are excited by an inter-conduction band transition, thermalized electron-electron scattering within 20 fs. observed coherent phonons of folded modes, which become Raman active as a result zone folding, those A1-symmetry longitudinal optical (A1-LO) mode. SiC, A1-LO forms coupled mode with plasmon, resulting asymmetrically broadened...

Precise spectroscopy of the hyperfine level system 167 Er-doped Y 2 SiO 5 was achieved in frequency domain. By using an optical comb to stabilize light source accuracy on order hertz a long-term scale, Allan deviation < 10 Hz for integration time 180 s. As result, spectral hole-burning experiments yielded more accurate hole spectrum with narrow homogeneous linewidth. The method opens way straightforward exploration relaxation mechanisms domain by simple steady-state measurements.

We created high-resolution atomic frequency combs (AFCs) and optimized the pulse sequence used in AFC memory to realize highly efficient quantum using 167 Er 3+ :Y 2 SiO 5 hyperfine level system. As a result, formation relaxation times of AFCs were revealed, with resolution 800 kHz by an appropriate pump light intensity. An efficiency 0.16% time 0.5 µs was achieved even under zero magnetic field 10 ppm concentration sample. This result paves way for realizing communication-wavelength memory.

A hybrid tabletop (2 m x 3 m) terawatt chirped-pulse amplification Ti:sapphire-Nd:glass laser (1054 nm, 475 fs, 500 mJ, 9 10(17) W cm(-2)) has been developed for laser-matter experiments. An overall gain factor of 10(10) was achieved the laser. The results applications in studies soft-x-ray Ni-like Mo 18.9-nm lasing and harmonic generation from solid surfaces are presented.