Cascaded Wavelength Conversion Research Articles

Efficient cascaded wavelength conversion under two-peak modulated Stark-chirped rapid adiabatic passage via grating structures

In this paper, we demonstrate a domain inversion crystal structure to study the cascaded three-wave mixing process in a two peak Stark-chirped rapid adiabatic passage. We have achieved efficient wavelength conversion, which can be performed in intuitive order and counterintuitive order. The requirement of crystal is reduced and the flexibility of structure design is improved. When the conversion wavelength is fixed, increasing the coupling coefficient between the two peaks can reduce the intensity of the intermediate wavelength while maintaining high conversion efficiency. Compared with the cascaded wavelength conversion process based on stimulated Raman rapid adiabatic passage, the two-peak modulated Stark-chirped rapid adiabatic passage has a larger convertible wavelength bandwidth. This scheme provides a theoretical basis for obtaining mid-infrared laser source via flexible crystal structure.

Millimeter wave switching for single carrier and aggregated filter bank multi-carrier signals in radio over fiber networks

The 5G wireless communication systems promise to utilize the RF spectrum more efficiently and use advanced modulation and access techniques to provide ultra-high data rate speeds. Millimeter wave (MMW) signals and MMW based systems are playing a fundamental role in achieving these requirements. The modules and devices, proposed for these systems, are intended to use the robust capabilities of photonic technologies. In this paper, we consider MMW switching and wavelength conversion using a semiconductor optical amplifier (SOA) as a technique to support MMW transmission over fiber-based networks. In particular, we exploit the nonlinear special effects in SOA to generate a switched optical single-sideband signal that carries aggregated filter bank multicarrier (FBMC) 5G signals. First, we optimize the SOA for single FBMC band switching. Then, the switching of six FBMC aggregated signals is considered. The intention is to investigate the performance of such aggregated FBMC signals after applying either single or cascaded wavelength conversion. The results include analyzing the performance in terms of bit error rate, optical signal-to-noise ratio, and error vector magnitude.

Three-process cascaded frequency conversion based on Stark-chirped rapid adiabatic passage

In the field of nonlinear frequency conversion, the cascaded frequency conversion scheme is an effective means to obtain new wavelengths. In this paper, we demonstrate efficient frequency conversion through three cascaded three-wave mixing processes based on Stark-chirped rapid adiabatic passage, which are different from previous cascaded wavelength conversion processes based on stimulated Raman adiabatic passage. Further, by analyzing the relevant parameters in the three-process cascaded frequency conversion models we have established, we find that the new scheme increases the conversion range and has lower restrictions on the conversion conditions while maintaining extremely low intermediate frequency intensity. These advantages allow our work to be applied to the acquisition of a mid-infrared or visible laser.

Efficient cascaded wavelength conversion based on Stark-chirped rapid adiabatic passage

We demonstrate a highly efficient process of cascaded wavelength conversion among three states that is based on the Stark-chirped rapid adiabatic passage technique, and enables the achievement of nearly complete wavelength conversion in the mid-infrared laser generation process. By analyzing the relevant parameters in the model, we identify various factors that affect the efficiency of the conversion process. Compared with traditional cascaded wavelength conversion based on the technique of stimulated Raman adiabatic passage, the new conversion process not only maintains a high efficiency but also keeps the intermediate frequency strength low along the interacting length and achieves better stability when the relevant parameters change.

Experimental investigation of polarization insensitivity and cascadability with semiconductor optical amplifier-based differential phase-shift keyed wavelength converter

We experimentally investigate the polarization insensitivity and cascadability of an all-optical wavelength converter for differential phase-shift keyed (DPSK) signals for the first time. The proposed wavelength converter is composed of a one-bit delay interferometer demodulation stage followed by a single semiconductor optical amplifier. The impact of input DPSK signal polarization fluctuation on receiver sensitivity for the converted signal is carried out. It is found that this scheme is almost insensitive to the state of polarization of the input DPSK signal. Furthermore, the cascadability of the converter is demonstrated in a two-path recirculating loop. Error-free transmission is achieved with 20 stage cascaded wavelength conversions over 2800 km, where the power penalty is <3.4 dB at bit error rate of 10−9.

Three-wavelength generation from cascaded wavelength conversion in monolithic periodically poled lithium niobate**Project supported by the National Basic Research Program of China (Grant No. 2013CB632704).

Tunable coherent emission is generated in a single-pass, cascaded wavelength conversion process from mode-locked laser-pumped monolithic periodically poled lithium niobate (PPLN). Three ranges of wavelength, including visible output from 628 nm to 639 nm, near-infrared output from 797 nm to 816 nm, and mid-infrared output from 3167 nm to 3459 nm, were obtained from the monolithic PPLN, which consists of a 10-mm section for 532-nm-pumped optical parametric generation (OPG) and a 7-mm section for 1064-nm-pumped sum frequency generation (SFG). A pump-to-signal conversion efficiency of 23.4% for OPG at 50 °C and a quantum efficiency of 26.2% for SFG at 200 °C were obtained.

Development of a new pulsed source for photoacoustic imaging based on aperiodically poled lithium niobate

We present the development of a source of deep-red radiation for photoacoustic imaging. This source, which is based on two cascaded wavelength conversion processes in aperiodically poled lithium niobate, emits 10 nanosecond pulses of over 500 µJ at 710 nm. Photoacoustic images were obtained from phantoms designed to mimic the optical and acoustic properties of oral tissue. Results indicate this device is a viable source of optical pulses for photoacoustic applications.

High-efficiency cascaded wavelength conversion based on adiabatic evolution

We demonstrate that the frequency conversion in the cascaded processes can be mapped uniquely to an associated three-wave mixing processes in adiabatic evolution. After solving the coupling wave equations of three-wave mixing processes, we immediately find the solutions of the corresponding cascaded coupled equations. Furthermore, we introduce a rather simple model, which displays the main features of the optical stimulated Raman adiabatic passage (STIRAP) but allows for analytic evaluation of all quantities. It performs two simultaneous three-wave mixing processes efficiently and without significant generation of an intermediate frequency. At last, we consider in detail the effects of the phase mismatch to the optical STIRAP efficiency, which show that the analytic bounds are seen to describe the transfer region very accurately.

Effective preemptive scheduling scheme for optical burst-switched networks with cascaded wavelength conversion consideration

We introduce a new preemptive scheduling technique for next-generation optical burst switching (OBS) networks considering the impact of cascaded wavelength conversions. It has been shown that when optical bursts are transmitted all optically from source to destination, each wavelength conversion performed along the lightpath may cause certain signal-to-noise deterioration. If the distortion of the signal quality becomes significant enough, the receiver would not be able to recover the original data. Accordingly, subject to this practical impediment, we improve a recently proposed fair channel scheduling algorithm to deal with the fairness problem and aim at burst loss reduction simultaneously in OBS environments. In our scheme, the dynamic priority associated with each burst is based on a constraint threshold and the number of already conducted wavelength conversions among other factors for this burst. When contention occurs, a new arriving superior burst may preempt another scheduled one according to their priorities. Extensive simulation results have shown that the proposed scheme further improves fairness and achieves burst loss reduction as well.

Addressing conversion cascading constraint in OBS networks through proactive routing

The negative impact of cascaded wavelength conversions has been largely ignored in optical burst switching performance evaluations. When optical bursts are transmitted all optically from source to destination, each wavelength conversion performed along the lightpath may cause some signal-to-noise deterioration. If the distortion of the signal quality becomes significant enough, the receiver would not be able to recover the original data. In this paper we examine the performance degradation when an upper bound on the number of wavelength conversions that a signal can go through is enforced. We refer to this constraint as conversion cascading constraint. We propose a novel proactive routing scheme under this constraint that considers the instantaneous link congestion at the moment when the bursts arrive. It has three major advantages: (1) utilize the same offset times for the same node pairs while providing dynamic routing without using any fiber delay lines (FDL); (2) decrease burst loss probability to a great extent; (3) mitigate unfairness among the bursts with different hop counts, which is even worse under the conversion cascading constraint if without any special treatment. We also extend the proposed mechanism to embrace a variant of regulated deflection routing which can further improve network performance.

Cascaded wavelength conversion as favorable application of nonlinear optical polymers

Nonlinear optical (NLO) polymers have been considered promising materials for wavelength conversion at a low pump power. However, they have not been readily adopted to practical applications due to their high absorption coefficients, especially at a shorter interacting wavelength. Our theoretical analysis proves that the influence of absorption coefficients can be mitigated significantly in cascaded wavelength conversion (CWC) processes. According to our example study, maximum conversion efficiencies for CWC can compare even with those for second-harmonic generation in many NLO polymers. Thus CWC can become a pertinent application of NLO polymers. However, to obtain such efficient CWC, several realistic problems should be resolved in practical devices.

Analysis of Ultrafast All-Optical OTDM Demultiplexing Based on Cascaded Wavelength Conversion in PPLN Waveguides

Ultrafast all-optical optical time-division multiplexing demultiplexing based on the cascaded second-harmonic generation and difference-frequency generation wavelength conversion in quasi-phase-matched periodically poled lithium niobate waveguides are studied theoretically. For a typical 160- to 10-Gb/s demultiplexing process, conversion efficiency, pulse shape, time delay, phase variation, and crosstalk are investigated in two different arrangements of the 160-Gb/s signals, and both the wavelength conversion and pulse reshaping can be realized

Monolithic red-green-blue laser light source based on cascaded wavelength conversion in periodically poled stoichiometric lithium tantalate

A compact, pulsed, red, green, and blue laser source based on cascaded quasi-phase-matched wavelength conversion in two periodic superlattices set in tandem in a single stoichiometric LiTaO3 crystal and pumped by a laser source at 532nm is reported. The white light equivalent flux obtained was 80lmper1W input with a green to white light power conversion efficiency of &amp;gt;30%. Unity power conversion is feasible in this monolithic approach.

Chromatic Dispersion Compensation via Mid-span Spectral Inversion with Periodically Poled LiNbO3 Wavelength Converter at Low Pump Power

Mid-span spectral inversion (MSSI) has to utilize high optical pump power, for its operation principle is based on a nonlinear optical wavelength conversion. In this paper, a low pump-power operation of MSSI-based chromatic dispersion compensation (CDC) has been achieved successfully, for the first time to our knowledge, by introducing a noise pre-reduction scheme in cascaded wavelength conversions with periodically poled LiNbO3 waveguides at a relatively low operation temperature. As preliminary studies, phase-matching properties and operation-temperature dependence of the wavelength converter (WC) were characterized. The WC pumped at 1549 nm exhibited a wide conversion bandwidth of 59 nm covering the entire C-band and a conversion efficiency of –23.6 dB at 11 dBm pump power. CDC experiments were implemented with 2.5 and 10 Gb/s transmission systems over 100 km single-mode fiber. Although it is well-known that the signal distortion due to chromatic dispersion is not critical at a 2.5 Gb/s transmission, the clear recovery of eye patterns was identified. At 10 Gb/s transmission experiments, eye patterns were retrieved distinctly from seriously distorted ones, and notable improvements in bit-error rates were acquired at a low pump power of 14 dBm.

ABSORPTION EFFECTS ON SECOND-HARMONIC GENERATION AND CASCADED WAVELENGTH CONVERSION IN NONLINEAR OPTICAL POLYMERS

Although nonlinear optical (NLO) polymers often exhibit very high optical nonlinearities, they have barely been applied to tentative NLO devices. The main reason lies in their high absorption losses, and this fundamental trade-off between optical nonlinearity and absorption, stems further advancement. Our theoretical analyses inform us that absorption effect is much less critical in cascaded wavelength conversion (CWC) than in second-harmonic generation (SHG), especially when absorption loss is very high at a given second-harmonic wavelength. Based on this result, we propose CWC as a more practical application of NLO polymers than SHG.

Cascaded All-Optical Wavelength Conversion for RZ-DPSK Signal Based on Four-Wave Mixing in Semiconductor Optical Amplifier

We have demonstrated ten-stage cascaded wavelength conversion together with 800-km transmission for 10-Gb/s return-to-zero differential phase-shift keying (RZ-DPSK) format using four-wave mixing (FWM) in semiconductor optical amplifiers. To the best of our knowledge, this is the first experiment reported on cascade wavelength conversion for RZ-DPSK format, which cannot be realized by methods based on cross-gain modulation and cross-phase modulation using a semiconductor optical amplifier. Compared with wavelength conversion using FWM for conventional on-off keying format, the signal-to-pump ratio for RZ-DPSK format can be increased to higher level to achieve better performance.

Analysis of Novel Cascaded&amp;lt;tex&amp;gt;$chi^(2)$&amp;lt;/tex&amp;gt;(SFG&amp;lt;tex&amp;gt;$+$&amp;lt;/tex&amp;gt;DFG) Wavelength Conversions in Quasi-Phase-Matched Waveguides

A novel cascaded second-order nonlinear interaction (/spl chi//sup (2)/), which is simultaneously based on sum frequency generation (SFG) and difference frequency generation (DFG) processes, is proposed and analyzed in quasi-phase-matched wavelength converters. Analytical expressions with clear physical insights are derived for the converted light. It is shown that the same conversion efficiency can be achieved by employing two pump sources with lower output power (P/sub p1/,P/sub p2/) in this novel scheme as compared with the conventional cascaded wavelength conversion technique based on second-harmonic generation and difference frequency generation (SHG+DFG) with a single higher power pump beam (P/sub p/=P/sub p1/+P/sub p2/). The theoretical results are consistent with the experimental ones. It is found that the pump wavelength difference can be separated by a span as large as 75 nm, while large 3-dB signal conversion bandwidth is retained. The results show that the novel cascaded /spl chi//sup (2)/ wavelength conversion scheme is very attractive for practical applications.

Cascaded wavelength conversions based on sum-frequency generation and difference-frequency generation.

A novel wavelength conversion scheme based on cascaded sum-frequency generation (SFG) and difference-frequency generation (DFG) is proposed and demonstrated in a MgO-doped LiNbO3 quasi-phase-matched waveguide. In this scheme, two pump wavelengths are set outside the communication band. It is shown that the same conversion efficiency can be achieved by use of two pump sources with lower output power (P1, P2) in this scheme compared with the conventional cascaded wavelength conversion technique based on second-harmonic generation and DFG with a single higher-power pump beam (P = P1 + P2) that is due to the use of a larger SFG nonlinear coefficient. The results significantly influence the selection of a suitable nonlinear interaction scheme for practical applications.

Numerical study of cascaded wavelength conversion in quadratic media

The nonlinear equations describing a stationary wavelength conversion process, performed through the cascade of two second-order interactions in a non-centrosymmetric medium, are numerically solved in terms of normalized variables. The behaviour of the conversion efficiency as a function of pump intensity, crystal length, phase mismatch and linear losses is discussed for both bulk and waveguide interactions.

Nonlinear characterization and modeling of periodically poled lithium niobate waveguides for 1.5-μm-band cascaded wavelength conversion

We present a nonlinear characterization of annealed-proton-exchange lithium niobate channel waveguides in view of their application for wavelength shifting in wavelength division multiplexing systems. We exploit second harmonic generation as a very sensitive technique to test waveguide uniformity and optical quality. The experimental results are successfully compared with those obtained using numerical simulations based on the finite element method. The analysis suggests useful criteria for the optimization of the fabrication parameters in order to enhance the efficiency of wavelength conversion processes.