Error-free Wavelength Conversion Research Articles

Monolithically integrated 80-gb/s AWG-based all-optical wavelength converter

We present a monolithically integrated all-optical wavelength converter. The converter consists of four semiconductor optical amplifiers for four separate inputs and an arrayed-waveguide grating. Error-free wavelength conversion with reasonable penalties for a 27 -1 pseudorandom binary sequence was shown for a single input 80-Gb/s signal. The device exploits cross-gain/phase modulation in a single amplifier and selects with a filter the blue-chirped spectrum of the new wavelength signal in order to speed up the device response. This device has a dimension of 1.7times3.5 mm2 and it can be operated to convert simultaneously four 80-Gb/s wavelength channels

Wide-band tunable wavelength conversion of 10-gb/s nonreturn-to-zero signal using cross-phase-Modulation-induced polarization rotation in 1-m bismuth oxide-based nonlinear optical fiber

We experimentally demonstrate that the use of only 1-m length of our fabricated Bismuth oxide-based nonlinear fiber readily allows for implementing a high-performance 10-Gb/s nonreturn-to-zero signal wavelength converter based on cross-phase-modulation-induced polarization rotation. No stimulated Brillouin scattering (SBS) suppression scheme was employed owing to a high SBS threshold of the fiber. Our wavelength converter is shown to provide a pattern-inverted or a noninverted output signal in the same configuration depending on the relative polarization directions between the probe and the polarizer. Error-free wavelength conversion over a 30-nm bandwidth is readily achieved for both cases, i.e., noninverted and inverted patterns.

High efficiency widely tunable SGDBR lasers for improved direct modulation performance

We report on two novel approaches to improve the differential quantum efficiency (DQE) of widely tunable 1.55-/spl mu/m lasers: the bipolar cascade sampled grating distributed Bragg reflector (BC-SGDBR) laser and the gain-levered SGDBR (GL-SGDBR) laser. Each is fabricated on a robust InGaAsP/InP photonic integrated circuit platform. The lasers demonstrate improved direct modulation performance over conventional SGDBR lasers. The BC-SGDBR laser was also monolithically integrated with a semiconductor optical amplifier and photodetector receiver in order to perform wavelength conversion. Error free wavelength conversion at 2.5 Gb/s and improvements in conversion efficiency are demonstrated.

Four-wave-mixing-based wavelength conversion of 40-Gb/s nonreturn-to-zero signal using 40-cm bismuth oxide nonlinear optical fiber

We experimentally demonstrate a compact and tunable four-wave-mixing-based wavelength converter using a Bi/sub 2/O/sub 3/-based nonlinear fiber (Bi-NLF). An only 40-cm-long Bi-NLF is used as a nonlinear optical medium for wavelength conversion of a 40-Gb/s nonreturn-to-zero (NRZ) signal with no additional stimulated Brillouin scattering (SBS) suppression scheme. The Bi-NLF used in this experiment has an extremely high SBS threshold owing to both its short length and relatively low Brillouin gain. The 40-cm Bi-NLF is fusion-spliced to standard single-mode fibers and its nonlinearity is measured to be /spl sim/1100 W/sup -1//spl middot/km/sup -1/. Error-free wavelength conversion over a 10-nm bandwidth at a 40-Gb/s NRZ data rate is readily achieved with a pure continuous-wave pump.

Widely tunable monolithically integrated all-optical wavelength converters in InP

Design, fabrication, and characterization of monolithically integrated widely tunable all-optical wavelength converters in InP is reported. The devices are based on the SGDBR laser integrated with different MZI-SOA wavelength converters. Error-free wavelength conversion at 2.5 Gbps was demonstrated over 50 nm input and 22 nm output wavelength range. Static operation, extinction ratio enhancement, signal reamplification, dynamic range, and chirp properties were characterized as well.

80 Gbit∕s wavelength conversion using semiconductor optical amplifier and optical bandpass filter

A wavelength converter is presented that is made out of a semiconductor optical amplifier and an optical bandpass filter. Error-free inverted wavelength conversion is demonstrated at a bitrate of 80 Gbit/s. This approach can be exploited at higher bitrates. A clear open eye indicating error-free wavelength conversion at 160 Gbit/s is also presented. This wavelength converter has a simple configuration and allows photonic integration.

Wavelength conversion of 160 Gbit∕s OTDM signal using bismuth oxide-based ultra-high nonlinearity fibre

Error-free wavelength conversion of a 160 Gbit/s OTDM signal by use of a 1 m length of fabricated bismuth oxide-based nonlinear fibre as a nonlinear medium generating cross-phase modulation-induced nonlinear birefringence is demonstrated. Wavelength tuning over a 10 nm range is also achieved.

All-fiber 80-Gbit/s wavelength converter using 1-m-long Bismuth Oxide-based nonlinear optical fiber with a nonlinearity gamma of 1100 W^-1 km^-1

We experimentally demonstrate the use of our fabricated 1-m-long Bi2O3 optical fiber (Bi-NLF) with an ultra-high nonlinearity of ~1100 W-1km-1 for wavelength conversion of OTDM signals. With successfully performed fusion splicing of the Bi-NLF to conventional silica fibers an all-fiber wavelength converter is readily implemented by use of a conventional Kerr shutter configuration. Owing to the extremely short fiber length, no additional scheme was employed for suppression of signal polarization fluctuation induced by local birefringence fluctuation, which is usually observed in a long-fiber Kerr shutter. The wavelength converter, composed of the 1-m Bi-NLF readily achieves error-free wavelength conversion of an 80-Gbit/s input signal.

2.5-Gb/s Error-Free Wavelength Conversion Using a Monolithically Integrated Widely Tunable SGDBR-SOA-MZ Transmitter and Integrated Photodetector

Error-free operation at 2.5 Gb/s was demonstrated for the first monolithically integrated widely tunable photocurrent-driven Mach-Zehnder based wavelength converter. Power penalties of 1-2 dB were measured across the 37-nm wavelength range of the sampled grating distributed Bragg reflector.

Wavelength conversion using nonlinear polarization rotation in a single semiconductor optical amplifier

We discuss an all-optical wavelength converter based on nonlinear polarization rotation in a single semiconductor optical amplifier. We show that inverted and noninverted wavelength conversion can be realized. We also demonstrate this wavelength-conversion concept can operate over a large wavelength range. Experiments show that error-free wavelength conversion can be obtained at a bit rate of 10 Gb/s.

First Demonstration of 40 Gbps Wavelength Conversion with No Pattern Effect Utilizing Cross-Phase Modulation in an Electroabsorption Waveguide

Wavelength conversion utilizing cross-phase modulation in an InGaAsP/InP-based semiconductor electroabsorption waveguide (EA-WG) was investigated. An error-free wavelength conversion at 40 Gbps was confirmed for the first time, although the power penalty, which was attributed to the insertion loss of the EA-WG, was relatively large, around 5 dB. The power penalty had no dependence on the pseudorandom pattern length, which verified that the pattern effect of the EA-WG based wavelength converter was negligible due to the fast absorption recovery of the EA-WG.

All-optical 2R regeneration and wavelength conversion at 20 Gb/s using an electroabsorption modulator

We describe experimental results of simultaneous all-optical 2R regeneration (reshape and reamplify) and wavelength conversion of return-to-zero data at 20 Gb/s using a reverse-biased electroabsorption modulator. The nonlinear optical transmission characteristic of the electroabsorption modulator reshapes the degraded input data by selective absorption of the optical noise and, therefore, increases the signal-to-noise ratio of the output, Reverse biasing the modulator allows fast recovery of the optical absorption for high data-rate operation without the detrimental bit-patterning effect. Error-free wavelength conversion and regeneration was obtained with more than 3-dB improvement of the receiver sensitivity at a bit-error-rate of 10/sup -9/.

Improving the Performance of All-Optical Wavelength Converters Using Fiber Gratings

We show that spectral filtering using a fiber Bragg grating as an optical discriminator improves the performance of semiconductor optical amplifier (SOA) wavelength converters. This technique increases the operation speed and reduces the data patterning effect of SOAs for non-return-to-zero (NRZ)operation. For return-to-zero (RZ) operation the fiber grating increases extinction ratio and preserves the data polarity. We use this technique to obtain error-free wavelength conversion of NRZ data at 10 Gb s in an SOA with 6 GHz dynamic bandwidth. We also use the SOA fiber grating to convert RZ data at 10 Gb s and show that the converted pulses can propagate error free over 20,000 km in a dispersion-managed system.

Technique for suppression of pattern dependence in a semiconductor-optical-amplifier wavelength converter

Wavelength converters that employ cross-gain modulation (XGM) in semiconductor optical amplifiers (SOAs) are limited in bit rate by the amplifier's pattern dependent response. We substantially suppress this pattern dependence by converting the phase modulation at the data transitions to amplitude modulation using a fiber grating filter. We use this technique to obtain error-free wavelength conversion of 10-Gb/s nonreturn-to-zero (NRZ) data using an SOA that showed an error floor at 10/sup -5/ bit-error rate (BER) when used alone.

Repeated wavelength conversion of 10 Gb/s signals and converted signal gating using wavelength-tunable semiconductor lasers

Repeated wavelength conversion of 10 Gb/s pseudorandom nonreturn-to-zero signals is demonstrated using semiconductor lasers that can be tuned wavelength over a broad range. Error-free tunable wavelength conversion with a very low power penalty can be achieved in both first and second wavelength conversion over a broad wavelength range from 1.486-1.573 /spl mu/m. The converted signal can be switched rapidly within this wavelength region. High-speed converted signal gating controlled by adjusting the bias current to the device active region is also demonstrated.

Broad-range tunable wavelength conversion of high-bit-rate signals using super structure grating distributed Bragg reflector lasers

Tunable wavelength conversion of a 10 Gb/s signal over a broad wavelength range of about 90 nm is achieved by using a super structure grating distributed Bragg reflector laser. The extinction ratio dependence of converted signal light on input signal light power and bias current to the laser active region is discussed. The extinction ratio becomes large when the input signal light power increases and the bias current decreases. Bit error rate measurements show that error-free, penalty-free wavelength conversion is achieved when the extinction ratio is large (12.5 dB) and that the bit rate which error-free wavelength conversion is possible increases as the input signal light power increases. Twenty Gb/s signal wavelength conversion is also demonstrated.