Hideaki Tobioka

Ultrafast all-optical logic gate using a nonlinear optical loop mirror based multi-periodic transfer function

A complete set of all-optical logic gate operations using a nonlinear-optical-loop-mirror-based multi-periodic transfer function is proposed. This scheme can operate all of sixteen two-input logic operations without changing configuration. We experimentally demonstrate AND, NAND, OR, NOR, XOR, and XNOR operations at 40 Gbit/s in a single configuration. We investigate the limitation of processing speed, and numerical simulation will show the feasibility of the processing speed up to 350 Gbit/s.

Design considerations of all-optical A/D conversion: nonlinear fiber-optic Sagnac-loop interferometer-based optical quantizing and coding

The authors describe in detail the design considerations of our previously proposed novel optical quantizing and coding method for all-optical analog-to-digital (A/D) conversion using nonlinear optical switches based on the Sagnac interferometer. The multiperiod transfer function, which is the key to quantizing and coding, is achieved through a careful design of the Sagnac interferometer. In the experiments, the intensity of the pulse train input to our A/D converter is manually changed, and the corresponding digital signals are successfully mapped generated. Although the input-pulse trains are not the sampling of real analog signal, the principle of our proposed 3-bit A/D conversion at a 10 gigasample per second (Gsps) rate is demonstrated. The proposed optical quantizing and coding, combined with existing optical sampling techniques, will enable ultrafast photonic A/D conversion without electronics. The potential in the frequency regime of over a few hundred gigasamples per second was investigated by using an optical switch that utilizes the optical Kerr effect for fast operation. It was found out that the wavelength allocations and temporal widths of control and probe pulses have to be optimized with respect to the group-velocity dispersion of highly nonlinear fiber.

Optical pulse compression based on stationary rescaled pulse propagation in a comblike profiled fiber

In this paper, optical pulse compression using a comblike profiled fiber (CPF) is theoretically and experimentally studied, in which highly nonlinear fibers and single-mode fibers are alternately concatenated. Stationary rescaled pulse (SRP), is the main focus, which is a recently discovered nonlinear stationary pulse in CPF. The fundamental characteristics of SRP are investigated, and SRP propagation is applied to the design of the CPF pulse compressor. Using the proposed design method, the specifications of the CPF can easily be controlled, such as the compression ratio per step of the CPF or the pedestal of the output pulse. Two experimental results of pulse compression using the CPF based on the proposed design method are shown: 1) pulse compression with a large compression ratio per step of the CPF and 2) low-pedestal and wideband wavelength-tunable compression. A parametric noise-amplification phenomenon occurring in a compression process for an optical pulse sequence is also numerically analyzed.

Versatile all-optical logic gate using nonlinear optical loop mirror based multi-periodic transfer function

A versatile all-optical logic gate using nonlinear optical loop mirror based multi-periodic transfer function is proposed. We experimentally demonstrate AND, NAND, OR, NOR, XOR, and XNOR operations at 40-Gb/s in a single configuration.

Duration-tunable 100-GHz sub-picosecond soliton train generation through adiabatic Raman amplification in conjunction with soliton reshaping

We demonstrate generation of 100-GHz soliton train with tunability of temporal duration from 0.84 to 2.1 ps by adiabatic Raman amplification with soliton reshaping, while keeping near transform-limit, low pedestal level and low stimulated Brillouin scattering.

2.1 kW single mode continuous wave monolithic fiber laser

A robust, alignment-free monolithic 2.1 kW single-mode continuous wave fiber laser, operating at 1083 nm is demonstrated. The laser is pumped with commercial fiber pigtailed multimode diodes through all-fiber pump-signal power combiners in a MOPA architecture. The oscillator was formed with high reflector and output coupler fiber Bragg gratings written in 11/200 μm (mode field/cladding diameter) single-mode fiber. The gain medium was a 19m OFS commercial 11/200 μm double clad Yb-doped fiber (DCY). Pump light was coupled to the oscillator using two 11/200 μm pump-signal power combiners (PSC). A total of 20 commercially available 58W pump diodes at 915 nm were used to generate 800W of signal, as measured before the amplifier. The Raman power after the oscillator was more than 60 dB below the signal power. The amplifier was built using 13 m of 14/200 µm DCY and two (18+1)x1 PSC combiners with more than 95% pump and signal light transmission. A total of 2 kW of power was used to bi-directionally pump the amplifier. The output was measured after 3 m 14/200 μm fiber, and 10 m 100/360 μm delivery cable. Total signal output power was 2.1 kW, corresponding to an amplifier slope efficiency of 77%. The Raman power is more than 30 dB below the signal power. At maximum power, no modal instabilities, thermal effects, nor power rollover were observed. With higher power pumps, it is predicted that a power level of 2.6 kW can be achieved with the Raman level below 20 dB.

Efficiency of highly nonlinear fiber in soliton converter for 40 Gbit/s 10,000 km fiber transmission

We show that highly nonlinear fiber is essential to reduce the input power, length, loss, and noise of a soliton converter, and that it actually halves the input power and length compared with a conventional DSF in 40 Gbit/s 10,000 km transmission.

Design of comb-like profiled fiber for efficient pulse compression based on stationary rescaled-pulse propagation

We propose the design procedure of a comb-like profiled fiber compressor based on stationary rescaled-pulse propagation, and demonstrate optical pulse compression of a 7-ps pulse train to 375-fs through the designed compressor with only four steps.

Widely tunable sub-picosecond compression of 40 GHz externally-modulated pulse train using 1.4 km long comb-like profiled fiber

We demonstrated the compression to 500 fs of a 40 GHz externally modulated pulse train with a wideband tunablity over 1530-1560 nm. A comb-like profiled fiber plays an important role in the widely tunable operation.

Programmably repetition tunable low pedestal femtosecond pulse train generation using comb-like profiled fiber

We demonstrated programmably repetition tunability from 5 MHz to 500 MHz on low pedestal 300 fs pulse train generation through the compression of gain-switched laser diode pulse by comb-like profiled fiber with normal-dispersion Er doped fiber.