Multiple Wavelength Conversion Research Articles

Multiple spatial and wavelength conversion operations based on a frequency-degenerated intermodal four-wave mixing process in a graded-index 6-LP few-mode fiber

We report on the experimental observation of a simultaneous threefold wavelength and spatial conversion process at telecommunication wavelengths taking place in a 6-LP-mode graded-index few-mode fiber. The physical mechanism is based on parallel and phase-matched frequency-degenerated intermodal four-wave mixing (FD-IFWM) phenomena occurring between the fundamental mode and higher-order spatial modes. More precisely, a single high-power frequency-degenerated pump wave is simultaneously injected in the four spatial modes L P 01 , L P 11 , L P 02 , and L P 31 of a 1.8-km long graded-index few-mode fiber together with three independent signals in the fundamental mode. By means of three parallel phase-matched FD-IFWM interactions, these initial signals are then simultaneously spatially and frequency-converted from the fundamental mode to specific high-order modes. The influence of the differential modal group delay is also investigated and shows that the walk-off between the spatially multiplexed signals significantly limits the bandwidth of the conversion process for telecom applications.

Multiple modal and wavelength conversion process of a 10-Gbit/s signal in a 6-LP-mode fiber.

We demonstrate experimentally a simultaneous threefold modal and wavelength conversion process of a 10-Gbit/s On/Off keying signal in a 1.8-km long graded-index 6-LP-mode fiber. The principle of operation is based on a phase-matched inter-modal four-wave mixing phenomenon occurring between the fundamental mode and 3 higher-order modes of the fiber. The converted signals show well-opened eye-diagrams and error-free processing.

Performance of Dynamic Pump-Wavelength Selection for Optical Packet Switch With Chained Parametric Wavelength Conversion

This paper proposes a scheme for pump-wavelength selection in an optical packet switch (OPS) with parametric wavelength converters (PWCs). In this scheme, pump wavelengths can be dynamically changed in all time slots, and more than one PWC is allowed to convert a wavelength in a chained manner. The objective of this scheme is to minimize the packet loss rates of the OPS. This scheme is called dynamic pump-wavelength selection with chained parametric wavelength conversion (DPS-C). DPS-C selects the pump wavelength for each PWC so as to maximize the number of successful requests, which refer to packets that wish to be forwarded to their requested output fibers. A PWC, which has the advantage of multiple wavelength conversion, uses a pump wavelength that can be flexibly chosen to define which wavelengths can be converted from/to. The set of original and converted wavelengths, where the pump wavelength is set in the middle of the two wavelengths, is called the conversion pair. Each PWC supports several conversion pairs. The OPS allows each wavelength to be converted using combinations of available conversion pairs, which are not used by any requests, from more than one PWC. A simulation shows that DPS-C outperforms the conventional scheme in terms of packet loss rates in both uniform and nonuniform traffic patterns.

Demonstration of bufferless optical packet switch with recursive stages of parametric wavelength converter

We demonstrate in an experiment an optical packet switching (OPS) using recursive parametric wavelength converters (PWCs) which uses the combination of two or more PWCs for wavelength conversions. The PWCs, which are based on four-wave mixing in highly nonlinear fibers, are possible for multiple wavelength conversion, allowing a share-per-node switching scheme, and thus significantly reducing the number of wavelength converters. Detailed demonstration of a developed OPS prototype using the joint of two PWCs indicates the generation of various wavelength conversion patterns which play an important role for OPS performance. The converted signals after two stages of PWC are obtained with error-free operations and low power penalties (BER=10−9) of about 2.0 dB. Numerical results also show significant improvement in packet blocking probability by the proposed recursive PWC-based OPS in comparison with the previous non-recursive schemes.

Optical Packet Switch Based on Dynamic Pump Wavelength Selection

This paper proposes an optical packet switch with parametric wavelength converters (PWCs), where the pump wavelengths are dynamically changed in every time slot. It is called the dynamic pump wavelength selection (DPS) switch. A PWC, which performs multiple wavelength conversion, uses a pump wavelength that can be flexibly chosen to define which wavelengths can be converted. To enhance switch performance, the DPS switch employs a matching scheme, which sets connections between input and output ports, in combination with dynamic pump wavelength selection; a conventional switch, on the other hand, performs matching with a given set of pump wavelengths that are configured in a static manner. The dynamic pump wavelength selection is used to select the pump wavelength for each PWC to maximize the number of wavelength conversion pairs supported. Numerical results from a simulation show that the DPS switch provides lower blocking rates than the conventional switch with pump wavelengths assigned statically, under both uniform and nonuniform traffic.

Deep UV light generation by a fiber/bulk hybrid amplifier at 199 nm

A high-pulse-repetition-frequency (PRF) pulsed light source in the deep ultraviolet region has been realized by a multiple wavelength conversion technique using a hybrid fiber/bulk amplifier system. Output of 199 nm with a power of 50 mW was achieved at 2.4 MHz PRF. The 1 microm amplifier consisted of a Yb-doped fiber amplifier and a Nd-doped YVO(4) amplifier. A 1.5 microm fiber master-oscillator power amplifier was employed as the other fundamental source. The amplifiers exhibited good amplification properties in pulse energy, polarization extinction ratio, and spectrum for nonlinear wavelength conversion.

Non-inverted multiple wavelength converter at 40 Gbit/s using 1550 nm quantum dot SOA

Error-free and low penalty (<2.5 dB) 1×4 multiwavelength conversion at 40 Gbit/s in a 1550 nm quantum dot semiconductor optical amplifier (QD-SOA) is demonstrated. The suggested converter makes use of a simplified filtering scheme based on a standard telecom grade dense wavelength division multiplexing demultiplexer (Demux). By detuning the wavelength of the continuous-wave probes out of the Demux's passband, a non-inverted wavelength converted signal is available at each of the Demux's outputs. Albeit significant fibre-to-fibre losses of the non-packaged QD-SOA (∼10 dB), only a low penalty is reported, mainly due to the low noise at the amplifier's output, with similar performance for a single and multiple wavelength conversion operation of the setup.

Multi-wavelength conversion at 10 Gb/s and 40 GHz based on nonlinear effects in HNLF

We present experimental results and numerical simulations of multiple-wavelength conversion of 10 Gb/s non-return-to-zero (NRZ) signals based on 2-pumps four-wave mixing and of 40Gb/s return-to-zero (RZ) signals through supercontinuum (SC) generation in a highly nonlinear fiber (HNLF). Two pumps with a 100 GHz separation located in the region of anomalous dispersion of the HNLF were combined to form a beat signal The 10 Gb/s NRZ signal anchored on ITU grid was converted with gain into 6 new signals and 6 idlers with 100 GHz separation. High quality sc with bandwidth exceeding 50 nm was generated when the HNLF was pumped with 25 dBm average power. Sliced sc can be used as a source for all-optical multicasting.

Multiple-wavelength conversion with gain by a high-repetition-rate pulsed-pump fiber OPA

The authors propose and demonstrate a novel multiple-wavelength converter with gain, based on a pulsed-pump fiber optical parametric amplifier (OPA). It generates multiple replicas of the signal, as well as spectrally inverted versions. The device is modeled by using quasi-steady-state OPA gain equations, as well as by the split-step Fourier method. Predicted conversion gains of up to 20 dB have been confirmed by experiments. A 10-Gb/s nonreturn-to-zero (NRZ) input signal was converted into several replicas, with penalties ranging from 0.26 to 1.24 dB for frequency shifts of /spl plusmn/k/spl times/100 GHz (k=1, 2, 3, 4).

Nonlinear frequency conversion with quasi-phase-mismatch effect

In conventional frequency conversion based on chi(2)-induced nonlinear optical effects, a number of phase-matching techniques have been deployed to resolve the phase mismatch between the interacting waves. In this work, we report that in the quasi-phase-matching scheme, the accumulation of the phase mismatch can induce a quasi-phase-mismatch effect. And on the contrary, instead of eliminating the phase mismatch, modulating the quasi-phase-mismatch effect can lead to bandwidth enhancement and multiple-wavelength conversion. Both of these are essential factors for applications in nonlinear frequency conversion. As examples, designs with reset-periodic and cascaded-periodic optical superlattices based on such modulation are presented.

All-optical wavelength conversion and tuning by the cascaded sum- and difference frequency generation (cSFG/DFG) in a temperature gradient controlled Ti:PPLN channel waveguide

All-optical single and multiple wavelength conversion and tuning by the cascaded sum- and difference frequency generation (cSFG/DFG) have been demonstrated in a temperature gradient controlled periodically poled Ti:LiNbO3 (Ti:PPLN) channel waveguide. Up to 4 channels of wavelength division multiplexed (WDM) signals which have 100 GHz channel spacing were simultaneously wavelength converted at a 16.8 degrees C temperature difference between both end faces in a Ti:PPLN waveguide. The 3 dB signal conversion bandwidth was measured to be as broad as 48 nm at single channel conversion. The maximum wavelength conversion efficiency and optical signal to noise ratio of wavelength converted channel were approximately -16 dB and -20 dB at a total pump power level of 810 mW.

Multiple Wavelength Conversion for WDM Multicasting by FWM in an SOA

Using multipump four-wave mixing in a semiconductor optical amplifier, we demonstrate a simple scheme for multicasting an input nonreturn-to-zero 10-Gb/s signal to six different output wavelengths, all compliant with a 200-GHz channel grid. The signals are successfully transmitted in a metro-like system.

Improving the Performance of All-optical WDM Networks based on Light-path Reservation

In this paper, three methods are proposed to improve the performance of all-optical WDM networks based on the light-path reservation scheme. These are wavelength conversion, multiple fibers and two-path routing. We begin by developing analytical models for static-routing networks based on the nonblocking centralized switch, bi-directional Manhattan Street network and de Bruijn network topologies. Analytical results show that in most cases, the multiple fibers and wavelength conversion schemes give the best performance, in terms of lowest blocking probability, for the nonblocking centralized network at light and heavy loads respectively. The reverse is true for the bi-directional Manhattan Street and de Bruijn networks. The choice depends on the values of the parameters such as network load and reservation level. The two-path routing method offers moderate improvement in performance for the de Bruijn network topology. In addition, there exist optimum reservation levels for attaining minimum blocking probabilities. The advantage of the three schemes is moderate in the centralized switch, and slightly less in the de Bruijn network. However, these schemes offer significant performance improvement for the bidirectional Manhattan Street network.