Aruto Hosaka

Demonstration of a Ti:sapphire mode-locked laser pumped directly with a green diode laser

We demonstrate a Ti:sapphire laser pumped directly with a green diode laser. A single 1 W InGaN diode laser operating at 518 nm is used as the pump source. Pulse durations as short as 62 fs and average output powers of up to 23.5 mW are obtained with chirped-mirror-based dispersion compensation and a semiconductor saturable absorber mirror (SESAM).

A proposal of multistage quantum pulse gate for a wavelength-division-multiplexed quantum simulator

Optical linear circuit is one of the most important parts for optical quantum computing. The optical circuit, which consists of mode mixers and phase shifters, has been used in various quantum protocols: cluster state generation, Boson sampling, and quantum random walk. To realize a large-scale linear circuit, waveguide-based quantum circuits have experimentally been demonstrated by some groups [1, 2]. However, such a waveguide-based circuit cannot overcome issues of flexibility and loss.

Modal analysis of photon-number statics in a supercontinuum laser pulse

A supercontinuum (SC) laser pulse, which is generated through third-order nonlinear process, is valuable light for various applications such as optical coherence tomography (OCT), and spectral measurement. Coherence of a SC pulse is one of the most important properties because the accuracy and sensitivity of these measurements are determined by its noise property. Recently, the second-order coherence property has been revealed by some numerical simulations and experiments [1, 2]. According to these previous reports, the coherence of the SC pulse has been almost lost through the spectral broadening process. However, the depletion of the coherence has been studied only in two bases: time and frequency. Thus, we experimentally study the coherent basis from noisy modes of the SC pulse by utilizing multimode quantum theory [3, 4].

Mode analysis of quantum nonlinear propagation of ultrashort laser pulse in an optical fiber

We develop a quantum multimode theory of nonlinear propagation in optical fibers. Using the developed theory, we numerically study potential of parallelism of fiber-based squeezed state generation by soliton-like and zero-dispersion propagations.

Generation of photon-number squeezed states with a fiber-optic symmetric interferometer

We numerically and experimentally demonstrate photon-number squeezed state generation with a symmetric fiber interferometer in an 800-nm wavelength and compared with an asymmetric fiber interferometer, although photon-number squeezed pulses have been generated only with asymmetric interferometers. Even though we obtain -1.0dB squeezing with an asymmetric fiber interferometer, since perfect spectral phase and intensity matching between displacement and signal pulses are achieved with a symmetric fiber interferometer, we obtain better squeezing of -3.1dB. We also numerically calculate and clarify this schemes usefulness at a 1.55-μm wavelength.

A mode-locked Ti: Sapphire laser pumped directly with a green diode laser

We report a mode-locked Ti:Sapphire laser pumped directly with a 1-W InGaN diode laser emitting at 518 nm. Pulse durations as short as 62 fs and average output powers of up to 23.5 mW are obtained.

Two novel schemes for photon-number squeezed pulse generation in ultrafast nonlinear fiber optics

We experimentally prove two novel techniques which solve issues in photon-number squeezed state generation with nonlinear Kerr effect: one is with an Er-doped fiber laser source, and the other is with a normal dispersion fiber at 800 nm. In the former case a collinear balanced detection technique is applied to eliminate spontaneous amplified emission noise. In the latter, negatively chirped laser pulses are used to achieve better matching with a local oscillator pulse.