Repetition Rate Of Pulse Train Research Articles

Low-noise, low repetition rate, semiconductor-based mode-locked laser source suitable for high bandwidth photonic analog–digital conversion

A semiconductor-based mode-locked laser source with low repetition rate, ultralow amplitude, and phase noise is introduced. A harmonically mode-locked semiconductor-based ring laser is time demultiplexed at a frequency equal to the cavity fundamental frequency (80MHz), resulting in a low repetition rate pulse train having ultralow amplitude and phase noise, properties usually attributed to multigigahertz repetition rate lasers. The effect of time demultiplexing on the phase noise of harmonically mode-locked lasers is analyzed and experimentally verified.

Dual-Wavelength Pulse Train Generation Based on Silicon-on-Insulator Optical Waveguides

In this paper, we present and numerically study a method with pump-probe configuration to generate ∼4.17-THz dual-wavelength ultrahigh-repetition-rate pulse train from the continuous-waves (CW) based on the submicron silicon-on-insulator (SOI) optical waveguides. An original ∼4.17 THz repetition rate pulsed pump, with femtosecond pulse duration, at 2900 nm (mid-wave infrared wavelength-MWIR) and 2-channel CW lights at 1450 nm and 1650 nm (near infrared wavelengths) are simultaneously launched into the silicon waveguide. Results show that, when both of CW lights with high intensity pulsed pump are co-propagating along the SOI waveguide, the CW lights will, respectively, experience normal and anomalous group velocity dispersion (GVD) regimes, leading to developing into two inverted ∼4.17 THz repetition rate pulse train by the combined effects of GVD and nonlinear frequency chirp induced by pulsed pump inside the waveguide. Moreover, the outcome pulse trains have short pulse duration and high extinction ratio (ER) comparing with the original pulsed pump if the systems parameters such as input power and waveguide length are judiciously adjusted.

Harmonically mode-locked semiconductor-based lasers as high repetition rate ultralow noise pulse train and optical frequency comb sources

Recent experimental work on semiconductor-based harmonically mode-locked lasers geared toward low noise applications is reviewed. Active, harmonic mode-locking of semiconductor-based lasers has proven to be an excellent way to generate 10 GHz repetition rate pulse trains with pulse-to-pulse timing jitter of only a few femtoseconds without requiring active feedback stabilization. This level of timing jitter is achieved in long fiberized ring cavities and relies upon such factors as low noise rf sources as mode-lockers, high optical power, intracavity dispersion management and intracavity phase modulation. When a high finesse etalon is placed within the optical cavity, semiconductor-based harmonically mode-locked lasers can be used as optical frequency comb sources with 10 GHz mode spacing. When active mode-locking is replaced with regenerative mode-locking, a completely self-contained comb source is created, referenced to the intracavity etalon.

Mode-Locked Bi-Doped All-Fiber Laser With Chirped Fiber Bragg Grating

We demonstrate a bi-doped fiber laser with dispersion compensation provided by a linearly chirped fiber Bragg grating. Reliable self-starting mode-locking was achieved by using an InGaAsN semiconductor saturable absorber mirror. The all-fiber laser generated short optical pulses with a duration of 1.9 ps at ~ 1165 nm. The large anomalous dispersion of the fiber grating ensured operation in the soliton pulse regime. This in turn enabled us to increase the repetition rate of the output pulse train up to 100.6 MHz via harmonic mode-locking.

SOA-based loop mirror for tunable pulse-width generation

We propose and experimentally demonstrate a system for the generation of pulses of tunable pulse-width as those required in high spectral efficiency optically routed networks. Pulse narrowing of 500 ps pulses by 90% is accomplished through a SOA based non-linear loop mirror. Optical switching through the SOA loop mirror is used to shape and carve these large pulses (e.g., 500 ps) generated by non-expensive low-frequency optoelectronic components to narrow pulses (e.g., 50 ps). We also calculate the minimum loop size and optimum repetition rate of the original pulse train for the generation of the shorter pulse-width pulse train.

Terahertz Optical Clock Generation with Tunable Repetition Rate and Central Wavelength Using Variable-Bandwidth Spectrum Shaper

Recently, a number of high-speed optical clock generation technologies have been developed due to their potential useful applications in different fields. Here, we propose a new terahertz optical clock generation technique with tunable repetition rate and central wavelength. The proposed optical clock generator consists of an frequency comb light source and a variable-bandwidth spectrum shaper (VBS). The VBS can generate arbitrary repetition rate pulse trains and waveform by controlling each spectral mode. We experimentally demonstrated optical clock generation with repetition rates of 1.28, 2.56, 3.0, and 4.0 THz.

Generation of gigawatt 10-GHz pulses with stable phase

The generation of microwave pulses in a 10-GHz range has been studied in a nonstationary relativistic backward wave oscillator (BWO) operating at a pulse train repetition rate of up to 300 Hz. Regimes with a stabilized phase of the high-frequency filling of pulses with respect to the accelerating voltage pulse front have been observed at a BWO peak output power of ∼1 and 3 GW. In pulse trains with a length of 10–100 s, the average output microwave power reached ∼1 kW.

Repetition-rate multiplication using a single all-pass optical cavity

We demonstrate a simple lossless method for the implementation of repetition-rate multiplication of a periodic pulse train. As it is showed, a single all-pass optical cavity (APOC) can increase the repetition rate of the output pulse train by factors of 2, 3, and 4. Two different APOC implementations, based on a Gires-Tournois interferometer and an all-pass ring resonator, are proposed and numerically demonstrated.

Analog and Digital Optical Pulse Synthesizers Using Arrayed-Waveguide Gratings for High-Speed Optical Signal Processing

In this paper, analog and digital optical pulse synthesizers using high-resolution arrayed-waveguide gratings (AWG) have been developed. The analog type of optical synthesizer consists of an AWG with an integrated 45deg, curved-surfaced mirror, a 4-f lens system, and an optically addressable spatial light modulator. The effective frequency resolution is 14.5 GHz. A dispersion compensation experiment is successfully carried out and a transform-limited short pulse has been obtained. This digital type of optical synthesizer comprises 30 frequency separated channels with a spacing of 12.5 GHz, where each channel includes an amplitude modulator and a phase modulator. The rectangular-shaped pulse is generated with this pulse synthesizer, together with a 12.5-GHz-spacing, optical frequency comb. The synthesizer can generate an optical pulse with any waveform. Moreover, using periodic characteristics of the pulse synthesizer, a 250-GHz repetition rate pulse train was generated, in combination with an ultrawideband, waveguide type of Fabry-Perot electrooptic modulator.

Controlled process for polymer micromachining using designed pulse trains of a UV solid state laser

A flexible workstation equipped with a solid state laser operating at 266 nm wavelength was used to machine holes in polyethylene terephthalate, polyimide and polycarbonate. An optical pulse picker was employed to reduce the high repetition rates of the laser, while a breakthrough sensor was used to avoid over-drilling of through holes. For each material, different repetition rates and designed pulse trains were tested to improve feature quality and process efficiency. Although the three polymers had very different reactions at this wavelength they all showed an improvement in feature quality with decreasing repetition rate due to a reduction in thermal effects. Up to 10 kHz the average depth per pulse remained unchanged and afterwards a slight increase was observed but this was accompanied by large uncertainties. Bursts of pulses at 40 kHz inserted inside the low repetition rate pulse train reduced the drilling time and the amount of debris redeposited without affecting the feature quality. It was found that a number of cleaning pulses after perforation eliminates the heat affected zone around exits. Holes with entrance diameters below 20 μm and exit diameters as small as 2 μm were obtained with high repeatability.

Repetition-Rate-Tunable Terahertz Optical Clock Generation Based on Optical Spectrum Synthesizer Using Attenuation and Phase-Tunable Arrayed Waveguide Grating

Recently, a number of high-speed optical clock generation technologies have been developed due to their potential useful applications in different fields of optical communication. We propose a new terahertz optical clock generation technique with a tunable repetition rate and a center wavelength. The proposed optical clock generator consists of a waveguide-type optical spectrum synthesizer using an attenuation and phase-tunable cyclic arrayed waveguide grating and a supercontinuum light generator. The optical spectrum synthesizer can generate arbitrary repetition rate pulse trains and a waveform by controlling each spectrum mode, using its variable optical attenuators and phase shifters. In this paper, we demonstrate optical clock generation with repetition rates of 1.28 and 2.56 THz experimentally.

Width-tunable pulse generation using four-wave mixing in bismuth based highly nonlinear fiber

This communication reports a simple configuration for the implementation of a compact and all-fiber based width-tunable pulse generator using four-wave mixing (FWM) effect in only 1.9-m of bismuth oxide based highly nonlinear fiber (Bi-HNLF). The width- tunable pulses are generated at repetition rates of 5 and 10 GHz. In the performed experiment, the pulsewidth of a 5 GHz repetition rate pulse train is tuned from 83 to 23 ps whereas the pulsewidth of a 10 GHz repetition rate pulse train is continuously tuned from 32 to 18 ps. An analytical model is presented for width-tunable pulse generation and the results agree well with the experimental findings. The effects of pump source timing jitter and intensity fluctuation on pulse generation are discussed.

Corrections to "Estimating Intensity Fluctuations in High Repetition Rate Pulse Trains Generated Using the Temporal Talbot Effect"

Corrections to "Estimating Intensity Fluctuations in High Repetition Rate Pulse Trains Generated Using the Temporal Talbot Effect"

Estimating intensity fluctuations in high repetition rate pulse trains generated using the temporal Talbot effect

We derive the upper limit of the peak intensity fluctuations for high repetition rate pulse trains generated using the fractional temporal Talbot effect for pulse repetition rate multiplication. Our analysis is general, can be applied to any input pulse shape, and can be used as a design tool to determine the input pulsewidth that will minimize the output amplitude fluctuations for a given multiplication rate.

Width and wavelength-tunable optical pulse train generation based on four-wave mixing in highly nonlinear photonic crystal fiber

We demonstrate both width and wavelength-tunable optical pulse train generation based on four-wave mixing in highly nonlinear photonic crystal fiber. By tuning the delay time between two pulse trains, the pulsewidth of the generated pulse train is continuously tuned. By tuning the wavelength of one of the pulse trains, the wavelength of the generated pulse train is also continuously tuned. In our experiment, the pulsewidth of a 5-GHz repetition rate pulse train is tuned from 88 to 19 ps and the pulsewidth of a 10-GHz pulse train is tuned from 39 to 19 ps. The 3-dB wavelength tuning range is about 70 nm.

All-optical frequency multiplication/recovery based on a semiconductor optical amplifier ring cavity

A novel scheme for all-optical frequency multiplication/recovery based on a semiconductor optical amplifier ring cavity is proposed and investigated numerically. The results show, for a 2.5GHz driving pulse train, it can be generated 5–25GHz repetition rate pulse trains with low clock amplitude jitter, polarization independence and high peak power. Furthermore, the extraction of the clock signal from a pseudorandom bit sequence signal can be realized based on the proposed scheme.

Talbot self-imaging and cross-phase modulation for generation of tunable high repetition rate pulse trains

We report generation of an ultra-high speed tunable pulse source with a repetition rate of 10, 30 or 40GHz by a technique implementing a tunable chirped fibre Bragg grating. An optical pulse train of variable repetition rate is derived in a tunable dispersion compensator via the fractional temporal Talbot effect, acting on the output of a 10GHz mode-locked laser. This ultra-high speed modulation is then used for phase modulation of a spectrally tunable probe by cross-phase modulation in highly nonlinear fibre, which is converted into constant-phase intensity modulation by spectral filtering.

A direct temporal domain approach for pulse-repetition rate multiplication with arbitrary envelope shaping

We present a direct temporal domain approach for pulse-repetition rate multiplication (PRRM) with envelope shaping using spectrally periodic optical filters. We show that the repetition rate of an input pulse train can be multiplied by a factor N using an optical filter with a free spectral range that does not need to constrained to an integer multiple of N. Individual output pulses in the newly generated pulse train have exactly the same intensity shape as those at the input. Furthermore, the amplitude of each individual output pulse can be manipulated separately to form an arbitrary envelope (profile) by optimizing N discrete values of the optical filter impulse response h(t). We demonstrate the direct temporal domain approach by designing a combined amplitude-and-phase filter based on a lattice-form Mach-Zehnder interferometer and simulation results show that PRRM with uniform and arbitrary profiles can be performed using these type of filters.

Generation of 40‐GHz pulse trains from a 5‐GHz dual‐driving rational harmonic mode‐locked semiconductor fiber‐ring laser

AbstractWe present and demonstrate a simple method of generating 40‐GHz repetition‐rate pulse trains from a rational harmonic mode‐locked semiconductor fiber‐ring laser with 5‐GHz dual‐driving signal by using pulse‐amplitude equalization. By adjusting the voltages applied to both arms of the modulator pulse trains with an eight‐times repetition rate are equalized in their amplitudes. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 489–491, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20511

Passive Q-switched mode locking of double-clading Yb:fiber laser with ion-implanted GaAs

We report the technique of the ion-implanted semi-insulating GaAs wafer used for passive Q-switched mode locking in double-cladding Yb:fiber laser. The wafer was implanted with 400-keV energy, 1016/cm2 dose As+ions, and was annealed at 600℃ for 20 min. At the pump power of 5W, we achieved output power of 200mW. The repetition rate of envelope of Q-switched mode locking is 50-kHz with a FWHM envelope of 4μs. The repetition rate of mode locked pulse train was found to be 15-MHz. This is the first report of such a kind of laser to the best of our knowledge.