Mixing In Photonic Crystal Fiber Research Articles

All fiber watt-level fiber source at 760 nm generated through four-wave mixing in a photonic crystal fiber.

There are limited fiber-based single-mode laser sources over the visible and near infrared range. Nonlinear conversion through four-wave mixing in photonic crystal fibers allows for the generation of new wavelengths far from a pump wavelength. Utilizing an all-fiber spliced configuration, we convert 1064 nm light into a W-level signal in the 750 nm - 820 nm spectral region. We demonstrate over 7.9 watts in the signal band, out of a custom photonic crystal fiber with M2 < 1.15. The input peak power as well as fiber length can be selected to keep the converted power in a 0.6 nm narrow emission band or broaden the output to 45 nm spectral band with spectral density greater than 50 mW/nm by pumping with higher peak powers.

Modeling nonlinear high-pressure sensors based on degenerate four-wave mixing in photonic crystal fibers.

We propose a high-pressure sensing mechanism in solid-core silica photonic crystal fibers (PCF) that is based on the nonlinear optical process of degenerate four-wave mixing. A quite simple configuration for the pressure sensor is given and is theoretically investigated by obtaining signal gain spectra. We focus on the Stokes and anti-Stokes sidebands that are generated during propagation of the field along the PCF due to the interplay of dispersion and nonlinear optical effects. We have considered wave propagation in the normal dispersion regime with the inclusion of negative fourth-order dispersion. We have also considered a pumping field with wavelength of 1076 nm and peak power of 3000 W that propagates along a PCF with 40 cm of length. We have optimized sensitivity, varying lattice pitch and air-hole diameter, and we have obtained high sensitivities of the Stokes and anti-Stokes lines of 3.672 and -0.146nm/MPa, respectively. The proposed sensors have potential applicability in high-pressure environments.

Switchable Dual-Wavelength Mode-Locked Fiber Laser Source for In-PCF Parametric Frequency Conversion Applied to CARS Microscopy

A self-started, switchable dual-wavelength all-polarization-maintaining mode-locked (ML) fiber laser for optical parametric generation (OPG) in photonic crystal fiber (PCF) applied to coherent anti-stokes Raman scattering (CARS) microscopy is reported in this paper. The complete laser setup is built in an all-fiber structure composed of commercial elements. It is based on a linear cavity with an active medium—namely, Ytterbium-doped fiber (YDF), a pair of fiber Bragg gratings as switchable partial mirrors between 1031.5 and 1049.7 nm, and a semiconductor saturable absorber mirror functioning also as the mode-locking device. The seed laser is amplified to 650 mW average power by two YDF amplifiers. The source delivers a pulse-train output of 30.9 ps at 1031.5 ps and 31.6 ps at 1049.7, a 3.1-MHz repetition rate, and over 200 nJ pulse energy and 6 kW of peak power at fundamental ML operation. The properties of this switchable dual-wavelength source ensures the correct OPG by degenerated four-wave mixing in PCF fulfilling the phase matching condition which corresponds to CARS resonance of 2850 $ {\mathbf{c}}{ {\mathbf{m}}^{ - 1}}$ (CH3-O molecular bonds) at 1031.5 nm and 1475 $ {\mathbf{c}}{ {\mathbf{m}}^{ - 1}}$ (CH2 δ molecular bonds) at 1049.7 nm.

Fiber Optical Parametric Oscillator and Amplifier for CARS Spectroscopy

We demonstrated coherent anti-Stokes Raman scattering spectroscopy based on fiber optical parametric oscillator and amplifier utilizing four wave mixing in photonic crystal fibers. The output powers and spectra of generated signals were analyzed in detail for various regimes involving spontaneous, stimulated, and amplified parametric processes. The optical parametric oscillator provided tunable signal pulses from 780 to 787 nm with a spectral bandwidth of 3.0 nm, which were then used to seed a fiber optical parametric amplifier, resulting in signal pulses with an average power of 33 mW and spectral bandwidth of 1.1 nm. Using the amplified signal and residual pump pulses, the anti-Stokes signal of polystyrene sample was detected, which confirms the feasibility of the proposed coherent anti-Stokes Raman Scattering light source.

Wavelength Tunable Source of Correlated Photon Pairs Based on Photonic Crystal Fiber

Quantum-correlated photon pairs with tunable wavelength are highly desirable in a number of quantum technologies. In this letter, we demonstrate a wavelength tunable source of the correlated photon pairs based on pulse-pumped spontaneous four-wave mixing in photonic-crystal fiber. The wavelengths of the correlated signal and idler photons can be continuously tuned at room temperature by adjusting the wavelength of pump originating from an ytterbium-doped fiber laser. The tuning range of the idler photons is 757–880 nm and the range of the signal photons is 1310–1610 nm, which covers the 1310- and 1550-nm telecom bands.

Resource-efficient fibre-integrated temporal multiplexing of heralded single photons

We present a multiplexed single photon source that re-synchronises heralded single photons generated by four-wave mixing in photonic crystal fibre using a fibre delay loop controlled by a single switch. By combining the probabilities of generating heralded single photons on four consecutive pump pulses we obtain an enhancement of the per-bin single-photon delivery probability. Our source demonstrates a way in which single-photon source multiplexing may be carried out with minimised resource overhead while retaining the benefits of a robust and alignment-free platform.

Fibre-integrated noise gating of high-purity heralded single photons

We present an all-fibre source of high-purity heralded single photons with an integrated conditional optical gate that reduces uncorrelated noise by almost an order of magnitude. Generating photon pairs by four-wave mixing in photonic crystal fibre, we observe with the noise gate active a factor of 7 reduction in the rate of single counts in the heralded channel with no measurable drop in coincidence count rate. In contrast to electronic post-selection of coincidence events, the real reduction in the flux of unwanted photons is beneficial for example to avoid bleaching light-sensitive samples or in generating entangled states.

Broadband Enhancement of Optical Frequency Comb Using Cascaded Four-Wave Mixing in Photonic Crystal Fiber

A cascaded intensity modulator (IM) and phase modulator (PM) are used to modulate a continuous-wave (CW) laser and generate an optical frequency comb (OFC). Thus, the generated comb is utilized as an initial seed and combined with another CW-laser to generate four-wave mixing (FWM) in photonic crystal fiber (PCF). Results show that an initial flat 30 GHz OFC of 29, 55 lines within power fluctuation of 0.8 dB and 2 dB, respectively, can be achieved by setting the ratio of the DC bias to amplitude of sinusoidal signal at 0.1 and setting the modulation indices of both IM and PM at 10. Moreover, the 1st order of FWM created through 14 m of PCF has over 68 and 94 lines with fluctuation of 0.8 dB and 2 dB, respectively. Hence, the generated wavelengths of 1st left and right order of FWM can be tuned in a range from ~1500 nm to ~1525 nm and ~1590 nm to ~1604 nm, respectively.

Broad optical bandwidth based on nonlinear effect of intensity and phase modulators through intense four-wave mixing in photonic crystal fiber

This work investigates the advantages of nonlinear optics of a cascaded intensity modulator (IM) and phase modulator (PM) to generate an initial optical frequency comb. The results show that when the direct current bias to amplitude ratio, α=0.1, and the IM and PM have the same modulation index and are equal 10, seed comb is achieved; it is generated by the modulation of two continuous wave lasers. Hence, based on these parameters, an intense four-wave mixing is created through 9 m of photonic crystal fiber. Moreover, a broadband spectrum was achieved, spaced by a 30-GHz microwave frequency.

Demonstration of 100 Gbit/s optical time‐division demultiplexing with 1‐to‐4 wavelength multicasting using the cascaded four‐wave mixing in photonic crystal fiber with a single control light source

ABSTRACTDispersion‐flattened highly nonlinear (DF‐HNL) photonic crystal fibers are useful for ultrafast optical signal processing. In this article, 100 Gbit/s‐to‐10 Gbit/s optical time demultiplexing with simultaneous 1‐to‐4 wavelength multicasting is successfully demonstrated by use of the cascaded four‐wave mixing (FWM) in a 50 m DF‐HNL photonic crystal fiber, for the first time. This scheme uses a single control‐pulse light source only and a simple architecture. The wavelength multicasting of the time‐demultiplexed optical signal is achieved on four wavelength channels of which two can have the minimum power penalty of 3.2 dB at 10−9 bit error rate compared to the 10 Gbit/s back‐to‐back measurement. With the cascaded FWM, our proposed scheme can be used to improve the functionality of ultrahigh‐speed optical time‐division multiplexed systems/networks so as to support wavelength multicasting applications in a cost‐effective manner. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2330–2335, 2014

Photonic crystal fibre-based source of heralded single photons with high mode purity and efficiency

We demonstrate and characterize a heralded single photon source which is based on the signal and idler photon pairs generated from pulse pumped spontaneous four wave mixing in photonic crystal fibre. The heralded single photons are approximately in a pure temporal mode, achieved by eliminating the frequency correlation of the photon pairs. Since the influence of Raman scattering is negligible and no narrow bandpass filter is employed, the heralding efficiency of the source is up to 85%. When the production rate is 0.002 pair/pulse, the measured second-order intensity correlation function of the heralded single photons is , which is suppressed by a factor of more than 80 relative to the classical Poissonian light limit. In addition, the demonstrated source is pumped by a photonic crystal fibre laser, which makes the source more compact and low-cost.

All-optical format conversion from non-return-to-zero to return-to-zero based on dual-pump four-wave mixing in photonic crystal fiber

A novel all-optical format conversion scheme based on dual-pump four-wave-mixing (DP-FWM) in dispersion-flattened highly nonlinear photonic crystal fiber (DF-HNL-PCF) is proposed and experimentally demonstrated. The original non-return-to-zero (NRZ) format is converted into double return-to-zero (RZ) format by injecting NRZ signal and double synchronized clock signals into the DF-HNL-PCF. The DP-FWM effect generates two sideband components, which carry the same data information as the original NRZ signal with RZ format. The wavelength tunability and dynamic range of format converter are investigated. The optimum extinct ratio and Q factor of converted signals are 15 dB and 5.4, respectively. The advantages of this scheme are that the each wavelength of double channel multicasting signals is dependent and flexible. Moreover, the system is transparent to bit rate as well as modulation format, and achieves all-optical wavelength conversion and wavelength multicasting.

All-optical format conversion from non-return-to-zero to return-to-zero based on four-wave mixing in photonic crystal fiber

The conversion from all-optical non-return-to-zero (NRZ) to return-to-zero (RZ) format is a crucial technology in interfacing WDM and OTDM of future transparent photonic network. The conversion from all-optical single-to-dual NRZ to RZ format conversion is presented and experimentally demonstrated based on four-wave mixing (FWM) in a 50 m dispersion-flattened highly-nonlinear photon crystal fiber (DF-HNL-PCF). The original NRZ format is converted into RZ format by injecting synchronized clock signal into the DF-HNL-PCF. The FWM effect generates two sideband components, which carry the same data information as the original NRZ signal with RZ format. The proposed format converter has a wide and tunable operation wavelength range of 19.3 nm. The optimum conversion efficiency, extinct ratio and Q factor are -21 dB, 11.9 dB and 7.2, respectively. The system is transparent to both bit rate and modulation format. The advantage of this scheme consists in the ability of bandwidth scalable due to the fact that the dispersion flattening of HNL - PCF is used. Furthermore, it is all optical fiber, compact and robust, which makes it more competitive as well as easily accessible for use in practical optical communication systems.

Tunable dual-wavelength fiber laser based on an opto-VLSI processor and four-wave mixing in a photonic crystal fiber

A stable wavelength and wavelength spacing tunable dual-wavelength fiber laser based on an Opto-very-large-scale-integration (Opto-VLSI) processor and four-wave mixing (FWM) in a high-nonlinear photonic crystal fiber is experimentally demonstrated. The results show that the line width of the tunable dual-wavelength fiber laser is 0.02 nm, and the wavelength spacing can be tuned from 0.8 nm to 4 nm with a 0.15 nm step. Under the influence of the FWM, the uniformity is below 0.6 dB and the measured side mode suppression ratio (SMSR) is above 45 dB.

All-optical multicasting based on multi-pumpfour-wave mixing in photonic crystal fiber

All-optical multicasting is a key technology of future transparent photonic network, and in this paper it is presented and experimentally demonstrated based on four-wave mixing (FWM) with multi-frequency pump in 100 m dispersion flattened highly nonlinear photon crystal fiber (HNL-PCF). A signal together with double orthogonal pumps is input into the PCF, and four idlers at new frequencies can be generated through degenerate multi-frequency pump FWM processes, which carry the same data information as the input signal and then a 4×10 Gbit/s wavelength multicasting has been obtained with a tunable operation wavelength range of 35.2 nm and total channel span of 4.4THz. The optimal conversion efficiency and the optimal Q factor are -22 dB and 5.3, respectively. The system is transparent to both bit rate and modulation format. The advantage of this scheme consists in the ability of bandwidth, and the multicasting channel scalable due to dispersion flattening of PCF is used. Furthermore, it is all optical fiber, compact and robust, which makes it more competitive as well as easily accessible for the uses in practical optical communication systems.

Two-Photon Interference of Photon Pairs Created in Photonic Crystal Fibers

We investigate a method to produce photon pairs by four-wave mixing in photonic crystal fibers (PCFs). By controlling the wavelength of the pump light, which determines the phase matching condition for four-wave mixing, we can obtain a broader spectrum of photon pairs than undesired Raman-scattered photons. We observe two-photon interference of photon pairs from a PCF with the help of an unbalanced Mach-Zehnder interferometer. Two-photon interference fringes with 83% visibility, which exceeds the classical limit of 50%, are obtained.

Enhanced four-wave mixing and parametric oscillation in photonic crystal fibre

We demonstrate efficient four-wave mixing in photonic crystal fibres with nanosecond, 1047 nm pump pulses. The incorporation of a ring cavity configuration allows a parametric oscillator to be formed, generating up to 31 mW of average power at 790 nm with a conversion efficiency of 15%.

Supercontinuum generation through cascaded four-wave mixing in photonic-crystal fibers: When picoseconds do it better

By numerically solving the generalized nonlinear Schrödinger equation, we provide a comparative analysis of spectral and temporal transformations of pico and femtosecond laser pulses in a guided mode with a generic dispersion profile typical of a photonic-crystal fiber. We demonstrate that with an appropriate choice of the input laser pulse parameters, picosecond pulses are efficiently transformed into a supercontinuum emission through a cascade of phase-matched four-wave mixing (FWM) processes. For femtosecond pulses, soliton frequency-shifting phenomena tend to arrest such FWM cascades. In this regime, picosecond pulses can provide much higher efficiencies of supercontinuum generation, as well as much broader and much smoother spectra of output radiation compared to femtosecond pulses with the same peak power.

Photon pair-state preparation with tailored spectral properties by spontaneous four-wave mixing in photonic-crystal fiber

We study theoretically the generation of photon pairs by spontaneous four-wave mixing (SFWM) in photonic crystal optical fiber. We show that it is possible to engineer two-photon states with specific spectral correlation ("entanglement") properties suitable for quantum information processing applications. We focus on the case exhibiting no spectral correlations in the two-photon component of the state, which we call factorability, and which allows heralding of single-photon pure-state wave packets without the need for spectral post filtering. We show that spontaneous four wave mixing exhibits a remarkable flexibility, permitting a wider class of two-photon states, including ultra-broadband, highly-anticorrelated states.

Theoretical analysis of polarisation-insensitive wavelength conversion by four-wave mixing in photonic crystal fibre

Polarisation-insensitive wavelength conversion by four-wave mixing (FWM) has been demonstrated in a 20 m short nonlinear photonics crystal fibre. Theoretical analysis confirms that the combination of a 45° pump launch and a minimum pump-probe detuning is required to reduce the polarisation sensitivity of FWM to ∼1 dB.