Motoharu Matsuura

320 Gbit/s wavelength conversion using four-wave mixing in quantum-dot semiconductor optical amplifiers

In this study, we demonstrate error-free all-optical wavelength conversion of ultrahigh-speed intensity modulated signals by means of four-wave mixing in a quantum-dot semiconductor optical amplifier. Error-free performance at a bit rate of 320 Gbit/s is measured for the extracted 40 Gbit/s tributaries with a 3.4 dB average power penalty to the original signal.

Ultrawideband Wavelength Conversion Using Cascaded SOA-Based Wavelength Converters

An all-optical wavelength converter with a large wavelength hopping range is proposed and demonstrated. This converter consists of multistage cascaded wavelength converters using semiconductor optical amplifiers each with different gain band. Each of the cascaded wavelength converters enables us to perform both noninverted (NIV) and inverted (IV) operations. Conversion performance is compared at NIV and IV operations in terms of static characteristics as a function of input/output power of the converter. While good conversion performances are achieved at both operations, the IV wavelength conversion has better cascadability to obtain a high-quality converted signal for the cascaded scheme. Moreover, signal amplitude regeneration is demonstrated by repeating the IV wavelength conversion. Finally, we successfully demonstrate, for the first time, ultrawideband wavelength conversion, including over 300-nm wavelength hopping to the shorter wavelength side with a triple-stage cascaded wavelength converter

Performance of Optical Packet Switches Based on Parametric Wavelength Converters

In an optical packet switch (OPS), input fibers carry multiple wavelengths, each of which carries a packet to one output fiber. As several wavelengths from different inputs could be destined to the same output fiber, one wavelength can be connected and the others remain disconnected, losing the carried packets. Because of the multiple wavelengths available at an output fiber, wavelength conversion in the OPS of the unconnected wavelengths into those available can increase the number of connections. A parametric wavelength converter (PWC) provides multichannel wavelength conversion where wavelengths can be converted to another. A PWC uses a pump wavelength that can be flexibly chosen to define which wavelengths can be converted, defining the so-called wavelength conversion pairs. However, it is unknown which set of pump wavelengths, and therefore the set of connection pairs, should be selected to improve the OPS performance while the number of PWCs in the OPS is reduced. This paper proposes a pump wavelength selection policy for an OPS that uses different pump wavelengths, one for each PWC, within an arbitrarily selected interval. This policy is called a variety-rich (VR) policy. This paper also introduces a non-wavelength-blocking OPS (NWB-OPS) to make full use of PWCs. The switch performance is evaluated through computer simulation. The results show that the proposed policy with different pump wavelengths achieves the highest performance when compared with another of similar complexity. Furthermore, the performance study shows that small sizes of the interval to select a pump wavelength are more beneficial than larger ones.

Transmission performance of a wavelength and NRZ-to-RZ format conversion with pulsewidth tunability by combination of SOA- and fiber-based switches

An all-optical signal processing scheme coupling wavelength conversion and NRZ-to-RZ data format conversion with pulsewidth tunability into one by combination of SOA- and fiber-based switches, is experimentally demonstrated, and its transmission performance is investigated. An 1558 nm NRZ data signal is converted to RZ data format at 1546 nm with widely tunable pulsewidth from 20 % to 80 % duty cycle at the bit-rate of 10 Gb/s. The investigation on transmission performance of the converted RZ signals at each different pulsewidth is carried out over various standard single-mode fiber (SSMF) links up to 65 km long without dispersion compensation. The results clarify a significant improvement on transmission performance of converted signal in comparison with the conventional NRZ signal through tunable pulsewidth management and show the existence of an optimal pulsewidth for the RZ data format at each transmission distance with particular cumulative dispersion. The optimal pulsewidths of the converted RZ signal and its corresponding power penalties against the NRZ signal are also investigated in different SSMF links.

Ultrahigh-speed and widely tunable wavelength conversion based on cross-gain modulation in a quantum-dot semiconductor optical amplifier

We present ultrahigh-speed and full C-band tunable wavelength conversions using cross-gain modulation in a quantum-dot semiconductor optical amplifier (QD-SOA). In this study, we successfully demonstrated error-free 320-Gbit/s operation of an all-optical wavelength converter (AOWC) using the QD-SOA for the first time. We also demonstrated full C-band tunable operation of the AOWC in the wavelength range between 1535 nm and 1565 nm at a bit rate of 160-Gbit/s.

Multiple-channel optical signal processing with wavelength-waveform conversions, pulsewidth tunability, and signal regeneration

A multiple-channel multiple-function optical signal processor (MCMF-OSP) including wavelength-waveform conversions, pulsewidth tunability, and signal regeneration is realized through AND logic gate based on optical parametric processing with a pulsewidth-tunable RZ clock pump. The proposed scheme simultaneously offers four signal processing functions which are useful in wavelength-division multiplexing (WDM) transmission systems, and at network nodes with the necessity for multiple-channel data processing. After the discussions on the concept of MCMF-OSP, a proof-of concept experiment is demonstrated on four 10 Gb/s nonreturn-to-zero (NRZ) data format channels using nonlinearities in semiconductor optical amplifier (SOA) and highly nonlinear fiber (HNLF). A wavelength and waveform conversions to return-to-zero (RZ) modulation format are obtained together with pulsewidth-tunable range from 20% to 80% duty cycles for all input signals. The converted signals inherit the timing and waveform of the RZ clock pump, thus resulting in a time regeneration and large tolerance to narrow-band optical filtering (NAOF) and fiber accumulated chromatic dispersion (CD).

High-Speed Wavelength Conversion of RZ-DPSK Signal Using FWM in a Quantum-Dot SOA

We demonstrate an all-optical wavelength conversion of a return-to-zero differential phase-shift keying (RZ-DPSK) signal using four-wave mixing in a quantum-dot semiconductor optical amplifier. We successfully achieved low penalty operation of 0.56 dB using 40-Gb/s RZ-DPSK signal.

Optical Carrier Regeneration for Carrier Wavelength Reuse in a Multicarrier Distributed WDM Network

We experimentally demonstrate optical carrier regeneration for carrier wavelength reuse in a multicarrier distributed wavelength-division-multiplexing network. The regenerated signal with a wavelength well matched with the reused data signal and has high signal quality.

Time-Resolved Chirp Properties of SOAs Measured With an Optical Bandpass Filter

Chirp properties induced by semiconductor optical amplifiers (SOAs) are investigated by a simple chirp measurement method using an optical bandpass filter. We measure the chirp properties of signals generated by an SOA-based wavelength converter at noninverted and inverted logic operations. These results demonstrate well the features of the chirp properties induced by SOA.

Frequency control characteristics of a single-frequency fiber laser with an external light injection

Characteristics of a single-frequency erbium-doped fiber laser (EDFL) controlled by an external light source is investigated. The frequency control is achieved by cooperatively induced spatial hole-burning (SHB) formed by the interference between the lasing light and the external light. We evaluate the frequency stability of several cavity designs of the fiber laser and the frequency control characteristics in detail. Tunable operation as wide as 30 nm wavelength range with a good frequency stability is also demonstrated.