Single SOA Research Articles

80Gbits/s DPSK receiver-sensitivity improvement using balanced gain-compression and amplification inside an SOA balanced-receiver

A novel technique for 2R-regeneration (re-shaping and re-amplification) of received RZ or NRZ 80 Gbit/s DPSK data is demonstrated using numerical simulations. The technique is based on using a single SOA balanced-receiver for balanced gain-compression and balanced amplification of demodulated DPSK (OOK) data. The utilized SOA is polarization-insensitive with 100 ps recovery time, and the tested data is 2 23-1 PRBS long. The balanced configuration of co-propagating orthogonally-polarized and complementary OOK streams inside SOA introduce a negligible pattern-dependence at system output. The receiver has been tested by wide-range of input random phase and amplitude-noise showing a remarkable improvement in data quality-factor. The BER demonstrates a receiver-sensitivity improvement by more than 4 dB in both cases of single-ended and balanced-detected signals.

All-Optical Signal Processing Based on Nonlinear Effects in Semiconductor Optical Amplifiers

In this paper, we report our recent studies on developing nonlinear techniques based on a single SOA for all-optical signal processing at high-speed, with a focus on simple configurations employing commercial SOAs for several key all-optical network applications. Our researches are based on nonlinear polarization rotation (NPR), four-wave mixing (FWM) and cross-phase modulation (XPM) effects in a single SOA. We propose and demonstrate applications of the nonlinear techniques in all-optical logic gates, multi-function format coversion, tunable Lyot birefringent filter and multi-channel optical time division multiplexed (OTDM) demultiplexing.

High-performance all-optical or/nor logic gate in a single semiconductor optical amplifier with delay interference filtering

The authors have proposed and experimentally demonstrated all-optical logic gates using a single SOA and delay interference filtering that enable simultaneous logic functions of OR and NOR at 40 Gbits/s. The proposed scheme, which utilizes the combinative filtering profile of a delay interferometer and an optical bandpass filter, has great merits for use in generating logic outputs with high quality in terms of pulse shape, extinction ratio, and eye diagram. Reconfiguration between the two gates is achieved by adjusting the tunable filter and the delay interferometer.

Single SOA based 16 DWDM channels all-optical NRZ-to-RZ format conversions with different duty cycles

We demonstrate simultaneous NRZ-to-RZ conversion for 16 DWDM channels, using a single SOA and a subsequent delay interferometer (DI) acting as a comb-like filter to control the obtained pulse-width for all of the channels. The SOA is operated in deep saturation, resulting in weak cross gain modulation and cross phase modulation induced crosstalk between different NRZ channels. By adjusting the detuning between the peaks in the DI spectrum and each corresponding carrier, good quality RZ signals with different duty cycles can be achieved. Bit-error-rate measurements show negative power penalties for the obtained RZ signals with different duty cycles. Significant timing jitter reductions for all channels show the good regenerative performance of the proposed converter.

40-Gb/s All-Optical Serial-to-Parallel Conversion Based on a Single SOA

An all-optical serial-to-parallel converter (AOSPC) was experimentally demonstrated. It could potentially be used to process variable-length optical packets. This scheme mainly consists of wavelength interleaved pulse generation and the sequential multiwavelength conversion (SMWC). The SMWC is based on a single semiconductor optical amplifier. In this research, a 40-Gb/s serial optical signal was converted into four-channel 10-Gb/s parallel optical signals. This scheme has the advantages of a simple system configuration, integration potential, and polarization independency. In addition, the AOSPC is suitable for an input signal with a low optical signal-to-noise ratio and at the same time can regenerate degraded serial signals.

All‐optical 3R regeneration based on the XPM effect of semiconductor optical amplifier

AbstractWe propose a 40 Gb/s all optical 3R regeneration system. A high Finesse Fabry‐Perot (F‐P) filter (FSR = 40 GHz, finesse = 1012) and a gain‐saturated SOA are used to extract 40 GHz clock. Before the clock extraction, 40 Gb/s RZ optical signals are converted into a stable wavelength after noninverted wavelength conversion based on the XPM of a single SOA. In the all optical decision, dual SOAs in series were used to lengthen active region of SOA. The 40 Gb/s degraded RZ signals are regenerated based on the XPM of dual SOAs in series, when a 0.26‐nm OBPF is blue shifted with respect to the wavelength of extracted clock. The experimental results show better eye opening, the decreased timing jitter from 5 to 1.4 ps and the 15 dB improved optical signal to noise ratio (OSNR). © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1807–1810, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23473

All-optical 42.6 Gbit/s NRZ to RZ format conversion by cross-phase modulation in single SOA

A 42.6 Gbit/s all-optical non-retum-to-zero (NRZ) to return-to-zero (RZ) format converter using a single SOA followed by an asymmetrical Mach-Zehnder interferometer is presented. The format converter generates a correctly-coded RZ signal with a controllable duty-cycle. It has the advantages of flexible input N RZ wavelength, preserved input polarity, negative bit error rate power penalty and low switching pulse energy (15fJ).

Electrically tunable fast light at THz bandwidth using cascaded semiconductor optical amplifiers

Ultra fast non-linear processes are used to achieve an advance of 2 ps for a 600 fs pulse propagating through two SOAs in series. This corresponding 3.3-pulse advance is tuned continuously by changing the current applied to the devices. We propose an experimental scheme that uses a single SOA in a loop to emulate the propagation of pulse through multiple cascaded SOAs.

320-to-40-gb/s demultiplexing using a single SOA assisted by an optical filter

We demonstrate excellent all-optical demultiplexing of 40-Gb/s base-rate channels out of 160- and 320-Gb/s single polarization optical time-division-multiplexed data streams. The demultiplexer utilizes a semiconductor optical amplifier and an optical filter placed at the amplifier output. The center wavelength of the filter is blue-shifted from the wavelength of the clock signal, so that ultrafast chirp dynamics can be employed for optical switching. Error-free demultiplexing was achieved at very low optical switch powers: 3.5 mW (160-Gb/s data), 6.3 mW (320-Gb/s data), and 0.09 mW (40-GHz clock). The proposed demultiplexer has a simple structure and allows monolithic integration.

All-optical Half-adder using a Single UNI Gate

A new scheme for an all optical integrated half-adder based on UNI (Ultrafast Nonlinear Interferometer) technique is proposed. This half-adder derives directly from a simultaneous XOR/NOTXOR gate based on a UNI gate and a single SOA which we demonstrate at 10 Gbit/s. A difference between our scheme and the traditional UNI structure is the usage of a counter-propagation geometry.

Bandwidth enhancement of SOA-based switches using optical filtering: theory and experimental verification

We present small-signal response measurements on all-optical switches based on a single SOA followed by an optical filter. Both asymmetric MZI and band-pass type filters are investigated and theoretical predictions of a large modulation bandwidth enhancing effect are verified. The small-signal measurements of the DISC switch (SOA and asymmetric MZI) are the first of their kind.

반도체 광증폭기의 상호 이득 변조를 이용한 2.5 Gbps 다채널 가변형 파장변환기

본 논문에서는 파장 분할 다중화 방식 광통신에의 적용을 목적으로 하는 다채널 가변형 파장 변환기(Wavelnength Convertor)를 구성하여 이의 성능을 분석하였다. 파장 변환기는 반도체 광증폭기(SOA : Semiconductor Optical Amplifier)의 상호 이득 변조(XGM : Cross Gain Modulation) 특성을 이용한 파장 변환 방식이 이용되었다. 2.5 Gbps 광통신 기반 100 CHz의 채널 간격을 갖는 다채널 신호들에 대한 파장 변환 성능을 측정, 분석하였다. 본 파장 변환기의 상호 이득 변조 성능을 측정한 결과, 소광비(Extinction Ratio)와 비트 오류율(BER : Bit Error Rate) 등의 검증에서 2.5 Gbps 기반의 파장 분할 다중화 방식 광통신에 사용하기에 충분한 성능을 보였으며, 이를 통해 최근 개발된 상호 위상 변조 방식(XPM Cross Phase Modulation)의 다채널 파장 변환기와 비교해 상대적으로 간단한 구조를 가지고 제작 및 변조 효율에 우위를 보이는 파장 변환기로서 대체될 수 있음을 밝힌다. A new structure of tunable wavelength converter based on XCM in SOA was tried and analyzed. This converter used single SOA and had very simple structure. In this paper, results were experimentally obtained and demonstrated. Pump signal was generated with NRZ <TEX>$(PRBS\;2^{31}-1)$</TEX> and data rate 2.5 Gbps. WDM multi conveted signals showed more than 8.3 dB extinction ratio. For BER performance, all these converted signals had within 5.0 dB power penalty compared with the pump signal. With these results, we showed that this converter was suitable for 2.5 Gbps WDM multi-channel wavelength converting.

Polarity-preserving SOA-based wavelength conversion at 40 Gbit/s using bandpass filtering

All-optical wavelength conversion is demonstrated at 40 Gbit/s, using a single SOA and a bandpass filter. The scheme is very simple, requires a record low switching energy of ∼3 fJ, and preserves data format and polarity.

A polarization-independent and contrast-ratio-enhancing module for all-optical wavelength shifting using SOA's

We demonstrate a polarization-independent and contrast-ratio-enhancing all-optical wavelength shifting module using polarization-dependent SOA's. When comparing our robust module to a single polarization-dependent SOA wavelength shifter, we reduce the polarization dependence from 3.5-0.5 dB and the contrast-ratio-induced power penalty from 5-1.5 dB when upshifting over 19 nm at 1 Gb/s.