Pulse Repetition Rate Multiplication Research Articles

Repetition-Rate Multiplication of an Electrooptic Pulse Source Using the Temporal Talbot Effect: A Theoretical Analysis

Spectral line-by-line control of an optical frequency comb derived from a sinusoidally phase-modulated continuous-wave laser allows to generate a pulse train with repetition rate equal to the modulation frequency. Here, we study pulse repetition-rate multiplication by an integer factor using the temporal Talbot effect. We show that pedestals and/or satellite pulses present in the fundamental pulse train lead, in general, to multiplied trains with significant distortions. Optimum modulation conditions for generation of output pulse trains with minimum peak-to-peak pulse intensity variations and/or maximum extinction level are numerically analyzed.

Pulse repetition rate multiplication in fibre laser using higher-order passive modelocking

A simple technique that allows for the repetition rate multiplication of optical pulse trains generated in passively modelocked fibre lasers is experimentally demonstrated. This is achieved by initiating higher-order passive modelocking by using both a dual‐channel fibre Bragg grating and a Fabry-Pérot filter inside the fibre cavity. Continuous dark pulse trains with a repetition rate of 60 GHz were generated, which is a four-fold multiplication of the Fabry-Pérot free spectral range.

利用脉冲重复率倍增和时域泰伯效应实现毫米波脉冲的产生

A novel scheme was proposed to generate a millimeter-wave (MMW) optical pulse by combining pulse repetition rate multiplication (PRRM) technology and temporal Talbot effect (TTE). A cascaded Mach-Zehnder interferometer (MZI) lattice was used for PRRM, and a linearly chirped fiber grating (LCFG) was used as TTE. The basic principle was analyzed by using a Gaussian input short pulse and its characteristics were discussed by numerical simulation. It is shown that the proposed scheme is feasible for MMW signal generation and has potential merits for practical application of radio over fiber (ROF) technology.

Simultaneous repetition-rate multiplication and envelope control based on periodic phase-only and phase-mostly line-by-line pulse shaping

We experimentally demonstrate simultaneous pulse repetition-rate multiplication and periodic pulse-to-pulse peak-intensity control based on optimized periodic spectral line-by-line pulse shaping. Accordingly, the method allows us to generate multiplied pulse trains in which the amplitude of each single pulse in a period can be arbitrarily tailored. The technique is illustrated with the generation of 4×9 GHz arbitrary periodic pulse trains, including binary code patterns, from a 9 GHz uniform input pulse train. Special attention is paid to pulse train generation based on all-pass line-by-line filters.

Tunable pulse repetition-rate multiplication using phase-only line-by-line pulse shaping

We demonstrate a method for all-optical, tunable pulse repetition-rate multiplication of a mode-locked laser based on spectral line-by-line control. In particular, two-to-five-times repetition-rate multiplication of a 9 GHz source is achieved with very high fidelity.

Arbitrary Optical Waveform Generation Using Planar Lightwave Circuits

We provide an overview of the direct temporal domain approach for designing optical fllters for ultrafast photonic signal processing applications. We discuss difierent fllter designs, including lattice-form Mach-Zehnder interferometers and two-dimensional ring resonator arrays, to perform pulse repetition rate multiplication and arbitrary optical waveform generation. Simulation and experimental results are presented. 1. INTRODUCTION Techniques for the generation, control, and manipulation of optical pulses attract considerable interest for numerous applications and have become increasingly important in many scientiflc areas. Of speciflc interest are techniques for pulse repetition rate multiplication (PRRM), which are used to obtain ulrafast optical pulse trains from a lower repetition rate input pulse train, as well as for arbitrary optical waveform generation (AOWG). Traditional pulse shaping methods are based on frequency domain processing (i.e., spectral flltering) in which we speciflcally manipulate the difierent spectral components of the input pulse in amplitude and/or phase. However, the relationship between the input pulse spectrum and the target temporal waveform is not always straightforward, especially for phase-only flltering processes. In this paper, we present an overview of our recently developed direct temporal domain approach for designing optical fllters to achieve PRRM and AOWG. 2. THEORY

Ring Resonator Arrays for Pulse Repetition Rate Multiplication and Shaping

Using numerical simulations, we demonstrate the use of ring resonator arrays (RRAs) for pulse repetition rate multiplication (PRRM) and arbitrary envelope shaping to generate a pair of output pulse trains with arbitrary binary code profiles simultaneously from a single input pulse train. We investigate three configurations of RRAs: MtimesN, 1timesN, and Mtimes1. All can perform PRRM and generate two pulse trains with the required binary code profiles simultaneously; however, the two-dimensional (MtimesN) configuration suffers less waveguide loss. We also show that a nonlinear optical loop mirror can be used to remove the pulse-to-pulse phase variations in the output pulse trains

Pulse-amplitude equalization by negative impulse modulation for rational harmonic mode locking

We propose a novel technique based on negative impulse modulation for pulse repetition rate multiplication by rational harmonic mode locking with pulse-amplitude-equalized pulses directly from the laser cavity. We have generated a pulse train of 15 GHz with more than 16 dB suppression of unwanted amplitude modulation spurs by using a 1 GHz RF signal. This is the highest suppression ratio for a repetition rate multiplication factor of 15 to our knowledge.

Classical coupled oscillators model of the rational harmonic mode locked laser

A coupled modes method is proposed to simulate the active mode locked laser. In this method, the electric fields of optical modes in the laser cavity are treated as free classical oscillators. The optical modulator provides the coupling among them. It is found that the eigenvalue of this coupled system is corresponding to the threshold optical gain, and the eigenfunction is corresponding to the optical field of each mode. The simulation results agree with the Master equation and experiments. Especially the model can be applied to the rational harmonic mode locking case by introducing the concept of ghost modes. The multitrip photons form a set of ghost modes or very weak oscillators. These ghost oscillators play the crucial rule working as the bridge to transfer energy and couple the real cavity modes/oscillators together. The model demonstrates both time domain pulse repetition rate multiplication and the frequency domain mode distribution. The proposed method will help understand the physics of rational harmonic mode locking mechanism and assist the design of devices such as optical pulse generator and multiwavelength laser. Therefore it should have great application in the optical signal generation and processing.

Complete family of periodic Talbot filters for pulse repetition rate multiplication

We introduce a new family of equivalent periodic phase-only filtering configurations that can be used for implementing the Talbot-based pulse rate multiplication technique. The introduced family of periodic Talbot filters allows one to design a desired pulse repetition rate multiplier with an unprecedented degree of freedom and flexibility. Moreover, these filters can be implemented using all-fiber technologies, and in particular (superimposed) linearly chirped fiber Bragg gratings. The design specifications and associated constraints of this new class of Talbot filters are discussed.

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.

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.

Tunable dispersion compensator based on uniform fiber Bragg grating and its application to tunable pulse repetition-rate multiplication

A new technique to control the chromatic dispersion of a uniform fiber Bragg grating based on the symmetrical bending is proposed and experimentally demonstrated. The specially designed two translation stages with gears and a sawtooth wheel can simultaneously induce the tension and compression strain corresponding to the bending direction. The tension and compression strain can effectively control the chirp ratio along the fiber grating attached on a flexible cantilever beam and consequently the dispersion value without the center wavelength shift. We successfully achieve the wide tuning range of chromatic dispersion without the center wavelength shift, which is less than 0.02 nm. We also reduce the group delay ripple as low as ~+/-5 ps. And we also demonstrate the application of the proposed tunable dispersion compensation technique to the tunable pulse repetition-rate multiplication and obtain high-quality pulses at repetition rates of 20 ~ 40 GHz.

Pulse repetition rate multiplication using phase-only filtering

The fact that temporal Talbot (self-imaging) effects of periodic optical pulse sequences are not necessarily restricted to first-order dispersive media is demonstrated and the required conditions for achieving integer and fractional Talbot phenomena in a general dispersive medium are derived. These results are of interest for implementing lossless pulse repetition rate multiplication using customised allpass phase-optical filters.

2 ~ 5 times tunable repetition-rate multiplication of a 10 GHz pulse source using a linearly tunable, chirped fiber Bragg grating

We experimentally demonstrate a simple scheme for the tunable pulse repetition-rate multiplication based on the fractional Talbot effect in a linearly tunable, chirped fiber Bragg grating (FBG). The key component in this scheme is our linearly tunable, chirped FBG with no center wavelength shift, which was fabricated with the S-bending method using a uniform FBG. By simply tuning the group velocity dispersion of the chirped FBG, we readily multiply an original 8.5 ps, 10 GHz soliton pulse train by a factor of 2 ~ 5 to obtain high quality pulses at repetition-rates of 20 ~ 50 GHz without significantly changing the system configuration.

Generation of a 100-GHz optical pulse train by pulse repetition-rate multiplication using superimposed fiber Bragg gratings

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.

Compression of periodic light pulses using all-optical repetition rate multiplication

We propose a novel method for compression of periodic optical pulses based on all-optical repetition rate multiplication of pulses without requiring propagation in a dispersive delay line. The compression principle is explained using the temporal Talbot effect. The proposed method is demonstrated experimentally with the generation of ∼20 ps pulses from cw radiation of a laser diode. The repetition rate multiplication is performed with fiber Bragg gratings. The proposed method simultaneously implements two important requirements of many fields, for example, of optical communications: pulse compression and pulse repetition rate multiplication.

Multiwavelength optical signal processing using multistage ring resonators

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.

Supermode stabilized coupled-cavity 5- and 10-GHz mode-locked Ti:Er:LiNbO/sub 3/ waveguide lasers

By coupling the active laser cavity to a passive low-finesse Fabry-Perot resonator, supermode stabilization of mode-locked Ti:Er:LiNbO/sub 3/ waveguide lasers for 5- and 10-GHz pulse repetition rates with side mode suppression ratios of 60 and 55 dB has been achieved. The 10-GHz source emits pulses with a pulsewidth of 5.7 ps and a time-bandwidth product lower than 0.52 within an RF frequency tuning range of 3.2 MHz. The 5-GHz source has been used in a 2/spl times/5 Gbit/s soliton transmitter. In a back-to-back measurement, a Q-factor of 25.1 dB has been obtained. In soliton transmission experiments over 160 km on a step-index fiber, an extrapolated bit error rate of 6/spl middot/10/sup -17/ has been measured. The passive cavity can serve also as a pulse repetition rate multiplier. Pulse repetition rate multiplication from 2.5 to 10 GHz has been demonstrated.