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We introduce a new class of high channel count multiwavelength comb filters based on sampled fiber Bragg gratings (FBGs). Our approach exploits the spectral fractional Talbot effect in sampled chirped FBGs (S-CFBGs). For specific conditions between the grating chirp and sampling period, the channel spacing can be reduced compared to the value obtained using conventional sampling techniques. In this way, the channel density can be multiplied without needing to increase the sampling period. Moreover, despite the fact that the grating is chirped, operating under the spectral Talbot regime ensures that the resultant in-band group delay characteristics are similar to those of a sampled uniform period FBG.

We propose and demonstrate a simple and practical method for measuring the amplitude and the phase of an ultrahigh-speed train of uniform pulses. Apart from a specially designed fiber Bragg grating (FBG) filter, the method only requires equipment that is standard in a telecommunications laboratory. The measurement is performed in the spectral domain where the intensity is easily recorded, while the spectral phase is characterized on the basis of beating signals obtained by filtering the pulse train with the FBG filter, which is tuned in wavelength by mechanical means. The practical capabilities and limitations (e.g., achievable spectral and temporal resolutions) of the proposed method are discussed.

Canadian Photonics Industry Consortium (CPIC);CMC Microsystems;INRS, Photonics North 2013 Conference -- 3 June 2013 through 5 June 2013 -- Ottawa, ON -- 101241, We describe the design and characterization of a silicon nanophotonic waveguide (SNW) and its use in a reconfigurable microwave photonic filter (MPF). The SNW is dispersion tailored for efficient on-chip four-wave-mixing. We use the onchip four-wave-mixing to increase the number of taps in our multiple tap delay line MPF. The tap levels are controlled by a programmable filter. Using a 12 mm long SNW reduces the footprint by five orders of magnitude compared to silica highly nonlinear fiber while only requiring approximately two times more input power. © 2013 SPIE.

We have implemented various dual-wavelength Tm3+:ZBLAN fiber lasers using upconversion pumping at 1064 nm. We demonstrate dual-wavelength operation at 800 nm, 1480 nm, and dual-band operation at 800/1480 nm.

We investigate the static and dynamic properties of partially gain-clamped two-stage L-band erbium-doped fiber amplifiers (EDFAs) in single- and double-pass configurations. While both amplifiers can be designed to provide the same gain-clamped performance, the double-pass configuration requires /spl ap/40% less pump power and /spl ap/22% shorter length of EDF in the second stage, and has a corresponding improvement in power conversion efficiency of 45%, but at the expense of an increase in noise figure (/spl ap/0.5 dB) and dynamic gain variation.

We demonstrate the use of superimposed fiber Bragg gratings (FBGs) operating in reflection as amplitude and phase filtering stages for multiplying the repetition rate of a given optical pulse sequence. In particular, we use a 1-cm-long structure of two superimposed linearly chirped FBGs to generate a continuous optical pulse train with a repetition rate of 100 GHz (duty cycle /spl ap/50%) at a wavelength of 1.55 /spl mu/m from a 10-GHz mode-locked fiber laser.

We develop a new family of high-weight two-dimensional wavelength-time codes for optical code-division multiple-access (OCDMA) that takes advantage of the antipodal signaling enabled by differential detection and uses relaxed auto- and cross-correlation constraints. We analyze the performance of the proposed codes and examine how the code size and correlation properties affect two important system parameters, namely the maximum number of codes that can be generated and the bit error rate as a function of the number of active users. We also show that this new family of codes can be used to implement high-performance OCDMA systems when combined with forward error correction coding: a system with 32 wavelengths and 41 time chips operating at OC-3 transmission rates (155.52 Mb/s) can support an aggregate throughput of /spl ap/41 Gb/s.

We demonstrate 40 Gb/s all-optical clock recovery using semiconductor fiber laser mode-locked by a nonlinear optical loop mirror. Clock signal with a timing jitter of 372 fs, and a power fluctuation of 0.089 are obtained.

We demonstrate dual wavelength operation, wavelength switching, and bistable behaviour in a Tm:ZBLAN fibre laser operating at 800 nm. The lasers are built in both single and cascaded-cavity configurations.

Partial discharge (PD) measurement has been deployed as a well established test method to monitoring the health of the insulation inside generators, transformers, gas insulated switch gear, and bus bars. There are different technologies to monitor the health of insulation by PD measurement, e.g., UHF high frequency capacitance measurement and acoustic emission using piezoelectric sensors. UHF technique has proven to be very sensitive but had troubles locating the sources of such PD activities. Piezoelectric acoustic sensors seem to be able to locate PDs, but their signal is weak and locating the sources using time of arrival method proves to be complicated: acoustics signal can travel through the insulation media such as oil or SF6, but they could also hit the metallic container and then travel to where the sensor is mounted. This paper will discuss a break through. First, a fiber laser can be formed by including a twin grating structure over an active fiber segment having Erbium and Ytterbium doping and pumped with 980 nm laser light. A DBR laser capable to follow very high frequency response is formed. Furthermore, this cavity can be made to be wavelength specific. A string of these can be installed over the walls of the transformer or a multi-segment GIS or Bus Bar. The signal from these laser sensors will become self identifying. These reflected signals can be demultiplexed with an array waveguide grating (AWG), which places the signal into buckets of various center wavelengths; therefore, each bucket can be related to where the sensor has been installed. The fiber laser sensor gives a higher signal to noise ratio than piezoelectric sensors, and these DBR lasers can be serially connected to diagnose the location of the PD events. There is no need for complicated software and algorithm to calculate and interpret the difference in time of arrival. Furthermore other fiber optics sensors such as temperature, moisture and loading can be installed to help to correlate PD with these operational and environment condition.

In this letter, we use a depth-first search algorithm to generate two-dimensional (2D) codes with unit auto- and cross-correlation properties for wavelength-time optical code-division multiple access (CDMA) systems. We examine how the code weight and size (number of wavelengths and/or time chips) affect the two important system parameters, namely the error probability (bit-error rate) in terms of multiuser interference and the maximum number of codes that can be generated. We show that 2D wavelength-time optical CDMA systems should use codes with low weight and a high wavelength to time chip ratio. The depth first search algorithm allows us to generate significantly more codes than previously proposed code construction algorithms; when used in conjunction with forward error correction, our approach potentially allows for a large number of simultaneous users operating with a BER

We show that all-pass filters based on multistage ring resonators can be used to perform optical signal processing. In particular, using numerical simulations, we demonstrate their use for performing real-time Fourier transformation and for pulse repetition rate multiplication (temporal Talbot effect) simultaneously over multiple wavelength signals.

We report an actively mode-locked tunable dual-wavelength erbium-doped fiber laser that uses parallel amplifiers in order to minimize gain cross-saturation effects. We obtain extremely stable, room-temperature dual-wavelength operation at a modulator drive frequency of 1035.38 MHz (corresponding pulsewidths of 115 and 130 ps). Furthermore, we can independently tune the power and wavelength of each lasing output signal without affecting overall output stability. In particular, we achieve a wavelength separation as narrow as 0.3 nm.

We demonstrate an approach based on a nonlinear optical loop mirror for generating and multicasting UWB signals. Five channels, including 1 monocycle and 4 doublet pulses, are generated from a single Gaussian optical pulse.

We propose an all-optical modulation format conversion method from binary phase-shift keying to quadrature phase-shift keying using a conventional delay line interferometer. We experimentally demonstrate error-free operation of the proposed conversion method at 12 Gb/s.

We characterize the steady-state strain characteristics of an all-fiber distributed Bragg reflector (DBR) laser sensor interrogated using a wavelength-to-power mapping system. We also demonstrate that the system is capable measuring dynamic strain from four parallel DBR sensors without crosstalk.

We report the demonstration of mechanically induced long-period gratings in ZBLAN fibers. We also show preliminary results of an all-fiber Mach-Zehnder interferometer based on cascading these gratings.

We demonstrate a wavelength tunable mode-locked semiconductor fiber laser at 40 GHz and 80 GHz using nonlinear polarization rotation. The laser can generate picosecond pulses with a timing jitter as low as 260 fs.

We demonstrate 40 – 200 GHz pulse train generation in a harmonic and rational harmonic mode-locked fiber optical parametric oscillator (FOPO). We characterize the tuning range and the corresponding pulse characteristics of the FOPO.

The optimization of a 2×2 silica-on-silicon Mach-Zehnder interferometer (MZI) thermo-optic switch is presented. The device consists of 2 multimode interference (MMI) couplers as splitter and combiner with metal heater strips for phase control. The switching characteristics of the devices have been examined in detail as a function of several parameters. The electrical power consumption of the switch has been reduced by a factor of 2 by etching trenches alongside the waveguide heaters located on the arms of the MZI, and the polarization dependent loss has been controlled and reduced through adjustment of top cladding properties. The effect on the response time of the switch of these design changes has been investigated. Detailed characterization of the devices will be presented, and trade-offs in optimization discussed. Incorporation of these device elements into increasingly complex components for new applications in optical signal processing will be demonstrated.

We characterize the dynamic response of a fiber Bragg grating (FBG)-based laser sensor system. The sensor system comprises a laser based on a reflective semiconductor optical amplifier and an FBG; interrogation of the wavelength shift is performed using a wavelength-to-power mapping with an optical filter. We demonstrate that the system is capable of detecting dynamic strain over a wide range of frequencies.

Multiplexed fluorescence-based assays are possible by immobilization of mixtures of different nucleic acid QD-bioprobes onto fused silica optical fibers, and onto glass surfaces of glass-PDMS microfluidic chips. Dynamic control of stringency by adjustment of the electrical potential to drive electroosmotic flow is advantageous. QD-bioprobes can be covalently anchored, or can be immobilized using a labile tethering system for removal and replacement.

We report the first demonstration of a long period grating in single mode ZBLAN fibers. The grating structure is mechanically induced by pressing a threaded rod onto a section of the fiber. A notch filter response is observed both near 1365 nm and 1525 nm. The advantages of the approach include tunability, repeatability and erasability.

[EN] In this study, a multi-wavelength laser monolithically integrated on InP is presented. A linear laser cavity is built between two integrated Sagnac loop reflectors (SLRs), with an arrayed waveguide grating (AWG) as frequency-selective device, and semiconductor optical amplifiers as gain sections. The power is out coupled from the cavity using a side diffraction order of the AWG. Simultaneous laser operation is provided for four wavelengths/cavities in the device. The termination of the laser cavities with integrated SLRs avoids using high-reflection coating. Only anti-reflection coating is used in the output facet of the chip., The authors acknowledge financial support from the European Commission FP6 project 004525 ePIXnet and the Canadian Institute for Photonic Innovations. The devices were fabricated through the InP Photonic Integration Platform JePPIX (coordinator D J Robbins), at the COBRA fab.

We provide a comprehensive investigation of all-optical modulation format conversion from OOK-to-DPSK at 10 Gb/s using cross-phase modulation. We also present results on OOK-to-DPSK modulation format conversion with wavelength multicasting. (2 pages)

Enabled by single-sideband-subcarrier modulation of both quadratures in the DSP-domain, we propose pilot-aided transmission in single-carrier systems to mitigate jointly laser phase noise and fiber nonlinearity. Performance improvement in linear and nonlinear regimes is demonstrated.

We experimentally demonstrate reconfigurable switching of four 10-Gb/s tributary channels of 40-Gb/s data using a programmable planar lightwave circuit and nonlinear wavelength conversion. Our device is a silica-on-silicon based 6-stage lattice-form Mach-Zehnder interferometer.

We propose a fiber Bragg grating (FGB) encoder/decoder for encoding/decoding broad-band pulses to implement hybrid two-dimensional (2-D) wavelength-time optical code division multiple access. The encoder/decoder is based on a 2-D array of FBGs that is fully reconfigurable and can generate various 2-D wavelength-time codes including those having variable code weight, multiple-pulse-per-row, or multiple-pulse-per-column.

Experimental and theoretical improvements to the propagation-mode near-field technique for refractive-index profiling have been made. The measured near-field profile is deconvoluted with the transfer function of the optical imaging system in order to recover the actual near-field profile. Anew equation is also derived in order to use these data to reconstruct the refractive-index profile of the waveguide under consideration. The improved method, which is valid for all relevant wavelength ranges, is demonstrated in the determination of the refractive-index profiles of two single-mode planar waveguides.

We use the direct temporal domain approach to design spectrally periodic optical filters for pulse repetition rate multiplication (PRRM) with envelope shaping. In particular, we demonstrate a tunable lattice-form Mach-Zehnder interferometer using Silica-based planar lightwave circuit (PLC) for arbitrary 4-bit binary amplitude code generation at 40 GHz and to increase the repetition rate of a 10 GHz input pulse train to 20 GHz or 40 GHz. In addition to PRRM and envelope shaping, the device also has the capability of arbitrary phase coding.

We demonstrate photonically-assisted generation of arbitrary RF waveforms with a bandwidth from 20 – 80 GHz using a reconfigurable silica-based planar lightwave circuit.

We demonstrate an approach for interrogating fiber Bragg grating sensors based on single bandpass microwave photonic filtering. The FBG sensor is a twin-grating structure and different temperature sensitivities are obtained at different RF frequencies.

The capabilities for RF-AWG in terms of waveform fidelity for three different incoherent photonic methods are revised and discussed: incoherent frequency-to-time mapping, incoherent MWP filtering with N discrete taps, and multi-wavelength pulse compression.

We show demodulation and demultiplexing of multi-channel WDM differential phase-shift-keying (DPSK) signals operating simultaneously at 10 Gb/s and 40 Gb/s using a 1x4 wavelength selective switch. We achieve error-free performance for four channels equally spaced by 100 GHz propagated over an 85 km dispersion-compensated link. We study the advantages and limitations of this new DPSK demodulator compared with the conventional delay-line interferometer.

We demonstrate a multiwavelength fiber optical parametric oscillator based on a nonlinear fiber as the gain medium. Using a transmission grating filter cascaded with a programmable filter as wavelength-selective elements, we achieve multiwavelength operation with 129 lasing wavelengths spaced apart by 25GHz. The power nonuniformity is less than 4.5dB with a power fluctuation of less than 0.1dB over a 20min period. Moreover, we realize tunable and reconfigurable functions over the entire lasing spectrum (approximately 25.6 nm), which greatly enhances the performance and flexibility of this laser.

We demonstrate high efficiency and wide bandwidth gain in a Ytterbium doped fiber amplifier. The highpowered amplifier has potential applications for use with a swept-source fiber ring laser in multi-channel optical coherence tomography (OCT) system. The ring cavity design includes a 976nm pumped dual core Yb doped fiber as the gain medium, where a rotating polygon mirror is used as a wavelength-sweeping filter for this source. The amplified spontaneous emission (ASE) had a spectral bandwidth of 1037-1145nm at -60dBm, where a tunable lasing bandwidth of the ring cavity ranged from 1057-1115nm. The highest output power, for both the ASE and lasing spectrum, with this configuration was ~200mW, however it is possible to have a larger bandwidth and a larger output power. Higher power, in the wattage range is achievable if free space components are employed. Pumped with 976nm light at 1.27W, the use of this novel dual core Yb doped fiber as an amplifier has been successfully demonstrated, as it provided a small signal gain of 29.6 dB at 1085nm, where the gain medium was successfully saturated during operation. This is important for the spectral shaping requirements of OCT to improve image quality. The gain was demonstrated for several different wavelengths and for several pumping powers at a 1085nm wavelength. Fourier domain mode locked operation (FDML) was achieved with a bandwidth of 15nm and a sweep rate of 51.4kHz. This laser source offers a low-cost, high power alternative for biomedical imaging with multi-channel optical coherence tomography.

In this study, a cascaded Raman fiber laser in Fourier domain mode lock operation (FDML) is presented. This laser utilizes a Ytterbium doped twin core pump laser source at 1109 nm. The pump light is directed to a cascaded Raman cavity, which consists of multiple cascaded fiber Bragg grating pairs and 3.86 km of dispersion compensation fiber, which provides Raman gain. The output wavelength of a cascaded Raman laser is determined by the Stoke's shift (≈ 60 to 70 nm in optical fiber) and the pump laser wavelength. The power build up in the cascaded Raman cavity and shift to higher Stoke's orders produce multiple spectral peaks. At higher Stoke's orders, the overlapping Raman peaks create broad bandwidth gain with relatively large gain ripples. FDML operation using a polygon-based tunable filter helps to suppress the ripples. The overall laser in linear operation has a bandwidth of 316 nm with a center wavelength of 1445 nm. An output optical power was measured to be (> 10 mW). On the other hand, the sweeping bandwidth was 35 nm with an output power in the micro-watt range. The utilization of broadband tunable lasers are important in applications such as swept-source optical coherence tomography for use in biomedical imaging.

We demonstrate a new photonically assisted reconfigurable radio-frequency waveform generator. The setup is based on phase modulating a multi-wavelength pulse source and subsequent compression in a dispersive medium. Under the appropriate conditions, we show that the photodetected electrical signal is broadband and coherent. Specifically, we show that this system allows for the synthesis of a reconfigurable finite-impulse-response filter where the number of filter taps is given by the number of wavelengths available from the multi-wavelength source and the reconfiguration is determined simply by their power and wavelength separation. We also show that this technique allows for time-multiplexing the synthesized waveforms, thus leading to an effective switching speed fixed by the clock rate. In particular, we show transitions between synthesized waveforms with a frequency content > 60 GHz in periods shorter than 100 ps.

We review recent work on developing multi-channel and multi-functional optical processing for DPSK signals. We demonstrate simultaneous demultiplexing and demodulation of multi-rate WDM-DPSK signals using a programmable wavelength selective switch as well as a tunable optical delay with amplitude noise regeneration of DPSK signals using a semiconductor optical amplifier.

We describe a polarization dependent formalism for DPSK and DQPSK receivers and show that the combined effect of PDL and PDFS cannot be decoupled making the birefringence axes non-orthogonal and independent of PDL axes.

We demonstrate demultiplexing of optical time division multiplexed (OTDM) signals to lower bit rates based on four wave mixing (FWM) in highly nonlinear fiber (HNLF). An all-optical tunable delay is implemented for selecting the desired OTDM channel. Both optical delay and demultiplexer are realized in a single piece of HNLF, thus reducing the component count. We show 40 Gb/s to 4 × 10 Gb/s demultiplexing and error free operation for the four channels.

We propose a multi-functional element that achieves both noise reduction and continuously tunable optical delay for phase modulated signals. We experimentally show 14.7 dB OSNR improvement and up to 882 ps tunable delay for a NRZ-DPSK modulated signal.

A dual wavelength actively modelocked erbium-doped fiber laser was constructed which generated pulses approximately 50 ps long with repetition rate 2.6 GHz at both 1544.1 nm and 1545.7 nm. The laser cavity incorporated a pair of dispersive gratings to produce temporal-spectral multiplexing of the pulses in the gain medium, which was observed to reduce cross-saturation effects.

We demonstrate a wavelength-encoding/time-spreading optical code-division multiple-access system that uses in-fiber chirped moire gratings for encoding/decoding. We present results for a system comprising four users, one desired and three interfering, and operating at the OC-12 transmission speed (622.08 Mbit/s). Our measurements verify the principle of encoding/decoding and the rejection of multiuser interference.

We propose and demonstrate the use of transmission edge filters based on apodized linearly chirped fiber Bragg gratings for providing power equalization among different wavelength channels in an erbium-doped fiber amplifier module. The filters we fabricated provide a dynamic range of /spl ap/13 dB, an amplitude variation of /spl plusmn/0.5 dB from an ideal linear edge, and negligible group delay in transmission. Using the grating filters, we demonstrate power equalization, with no observed variation in signal levels after compensation, for three WDM signals having >6-dB difference in power levels before amplification. Our technique can also be extended to provide active power equalization by incorporating a feedback loop.

We present the temporal counterpart of a spatial joint-transform correlator. This system optically measures the rf spectrum of a real-time spectral interferogram achieved by stretching a sequence of two time-multiplexed pulses. The optical rf analyzer makes use of the cross-phase modulation on a cw probe in a highly nonlinear fiber. We show that the optical spectrum appearing on the cw signal contains the information of the electric-field cross correlation of the signals under test. This device offers potential applications for all-optical pattern recognition of ultrashort pulses.

Distributed reflectors are proposed to implement centralized optical-layer fault detection, localization, and notification, in long-reach Passive Optical Networks. We introduce synchronous system and power budgeting algorithms. Our simulations demonstrate light-speed fault notification using off-the-shelf components.

We demonstrate a tunable 40 GHz mode-locked semiconductor fiber laser incorporating a nonlinear optical loop mirror. The laser is tunable over the C-band and generates picosecond pulses with a timing jitter less than 710 fs.

We propose and demonstrate a fiber laser system that is used to improve the measurement sensitivity and power efficiency in the context of mapping the wavelength encoded information of an array of FBG strain sensors to a power measurement.

We propose a low-power and low-cost tunable optical delay using wavelength multi-casting based on injection locking in Fabry-Perot laser and dispersion. We achieve error-free operation at a maximum delay of 954 ps.