Optical pulse compression in 1.5 μm wavelength region usinglarge-positive-dispersion fibre and grating pair

Optical pulse compression at 1.5 μm has been conducted. 20 ps (FWHM) optical pulses from a Tl:KCl-colour-centre laser were compressed into pedestal-free 1.2 ps pulses using a large-positive-dispersion fibre and a grating pair. In addition, 280 fs pulses were obtained from the resultant 1.2 ps through the soliton compression effect in a negative-dispersion fibre     

7× electrical pulse compression on an inhomogeneous nonlineartransmission line

A device which directly compresses electrical pulses using the concepts of soliton propagation along an inhomogeneous nonlinear transmission line is described. Numerical simulations on SPICE indicate that a 5 V input pulse with a FWHM of 66 ps can be compressed to a ⩾10 V output pulse with a FWHM ⩽5 ps. A compression factor of ⩾7 has been experimentally measured on a low frequency scale model compressor     

Transform-limited 5.6 ps optical pulse generation at 12 GHz repetition rate from gain-switched distributed feedback laser diode by employing pulse compression technique

12 GHz chirped optical pulses from a gain-switched 1.3 ?m distributed feedback laser diode are compressed to transform-limited 5.6 ps pulses by travelling through a dispersion shifted single-mode fibre with 46 ps/nm normal dispersion. A time-bandwidth product of 0.69 and a high on/off ratio of 20 dB are obtained for optimally compressed pulses.     

Picosecond optical pulse compression from gain-switched 1.3 ?m distributed-feedback laser diode through highly dispersive single-mode fibre

The first demonstration to compress the linearly chirped optical pulses from a gain-switched distributed-feedback laser diode (DFB-LD) is described at 1.3 ?m wavelength. By travelling through a highly dispersive single-mode fibre with 48 ps/nm normal dispersion, a 26 ps (FWHM) pulse having red-shift frequency chirping of 85 GHz (FWHM) is compressed to 8.3 ps with the time-bandwidth product of 0.71.     

Temporal compression of mode-locked pulses for laser-fusion diagnostics

Regenerative compression of mode-locked laser pulses has been developed to provide a temporally short probe pulse for diagnosing laser-fusion plasmas. A single mode-locked pulse injected into a regenerative amplifier is compressed by an intracavity saturable dye. Analysis indicates the best operational mode and choice of experimental parameters. Experiments using Nd:YAG and Eastman A9740 dye demonstrate an eightfold compression from 120 to 15 ps with a shot-to-shot stability of ±4 percent. An oscillator/regenerative compressor system demonstrates a 15 ps probe pulse synchronized within ±5 ps to a 1000 ps target-heating pulse.     

Stable 80-GHz short pulse generation using the cascaded polarization-maintaining fiber loop mirrors

In this work, an optical short pulse generator is designed consisting of a pulse compressor and cascaded notch filter type repetition rate doublers. The performance characteristics such as pulsewidth and peak power as a function of design parameters are studied. The pulse compressor is optimized based on the simulation results. The 6-ps-wide pulses at 20-GHz repetition rate directly generated from mode-locked fiber laser are compressed to 1.25-ps-wide pulses. Using a set of polarization-maintaining fiber loop mirrors, the repetition rate is quadrupled and stable 1.45-ps-wide pulses at 80 GHz are achieved.     

一种全光纤脉冲压缩器的理论分析

文章对由色散补偿光纤(DCF)、分布式拉曼放大的色散位移光纤(DSF)以及非线性光纤环镜(NOLM)构成的全光纤脉冲压缩器进行了理论分析和数值模拟.结果表明,光脉冲经DCF后可消除啁啾,为压缩提供有利条件;而经分布式拉曼放大的DSF后,脉冲得到了较大的压缩;最后再通过NOLM消基座.利用此压缩器可获得压缩率高且压缩效果好的光脉冲.     

Matched photonic bandgap fibre and fibre Bragg grating dispersion for all-in-fibre stretch pulse amplification

Kilowatt peak power pulses with pulse durations of approximately 1.5 ps within 5% of transform limit using an all-fibre stretch pulse amplification system are demonstrated. Efficient high-quality stretch pulse amplification is achieved using a matched chirped fibre Bragg grating and low nonlinearity photonic-bandgap hollow-core fibre. The nearly ideal recompression highlights the robustness of ultra-short picosecond pulses to group delay ripple in chirped fibre gratings.     

Improved Raman-fibre pulse delay measurement system

An improved design for pulse delay measurements using a Raman generating fibre pumped by a Nd:YAG laser has been realised. The reproducibility error in the measured delay times is only 2 ps RMS, because of strongly reduced jitter, compensation of long-term instability and prevention of irregularities in the shape of the pulses.     

Ultrashort pulse generation from an integrated single-chip dyelaser

In distributed-feedback (DFB) dye lasers pumped by a nanosecond-pulse laser, a train of picosecond spikes is generated by the relaxation oscillation. A single spike with a pulse duration of 50 ps is extracted in a plastic-waveguide DFB dye laser using a quenching technique. To compress this to femtosecond pulse, a new type of integrated pulse compressor is proposed, and its performances are analyzed. The compressor is composed of a plastic waveguide in which amplifier dye and saturable dye are alternatively doped. Computer simulation shows that the 50-ps pulse is compressed to 120 fs by passing through four stages of amplifier and saturable absorber pair. Using this scheme, we expect to construct a very compact and simple ultrashort pulse generator in which the whole system is integrated on a chip of a plastic waveguide     

Signal generation and transmission at 40, 80, and 160 Gb/s using a fiber-optical parametric pulse source

Short return-to-zero pulses (/spl sim/2 ps) are generated at bit rates of 40, 80, and 160 Gb/s using a fiber-optical parametric amplifier. The performance of the parametric pulse source is evaluated both back-to-back and in a 110-km transmission link. A receiver sensitivity of -33 dBm back-to-back was achieved after demultiplexing from 160 to 10 Gb/s. The power penalty at 160 Gb/s due to 110-km transmission was less than 2 dB. Very short pulses (0.5 ps) were also achieved when using the parametric amplifier as a compressor.     

Actively modelocked, quadruple-wavelength fibre laser with pump-controlled wavelength switching

An actively modelocked quadruple-wavelength erbium-doped fibre laser with two wavelengths in each of the C- and L-bands (with wavelength spacings of 3.5 nm and 0.4 nm, respectively) is reported. The pulse durations are 50-55 ps with corresponding time-bandwidth products of 0.48-0.63. By simple adjustment of the pump power, the laser can be switched to emit at any combination of the 4 wavelengths, without changing the repetition rate of the output pulses.     

Simple picosecond pulse generation scheme for injection lasers

A simple scheme is reported for generating picosecond optical pulses from injection lasers based on short electrical pulse excitation. An integrated step recovery diode impulse-train generator (`comb? generator) which gives 50 ps 25 V electrical pulses at 200 to 500 MHz rates is used to drive the injection lasers. Optical pulses as short as 40 ps are generated by the corresponding electrical drive pulses.     

Analysis of picosecond pulse shape synthesis by spectral masking in a grating pulse compressor

This paper analyzes the synthesis of arbitrarily shaped optical pulses by spectral filtering in a fiber-and-grating pulse compressor. Spectral filtering of phase and amplitude is achieved by masking the spatially dispersed frequency components within the compressor. We show that the spectral filter is the convolution of the mask with the beam's transverse intensity profile. We discuss the effect of diffraction from the features of the physical mask, and show how finite spatial resolution limits the range of attainable temporal profiles. The fundamental limitation on spectral resolution is derived. Spectra and temporal pulse shapes corresponding to a variety of physical masks are calculated and are found to be in excellent agreement with experiments done with compressed pulses from a mode-locked Nd: YAG laser.     

Nonlinear, dispersion-free 10 GHz optical pulse train transmission in distributed erbium-doped fibre

The transmission of a 10 GHz repetition rate optical pulse train over a 28.5 km long distributed erbium-doped fibre amplifier is reported. In the linear dispersion regime, the pulses broaden so that the tails of adjacent pulses overlap. However, given sufficiently high signal powers, the optical Kerr effect causes pulse narrowing back to the original 18 ps pulsewidth.<>     

Picosecond soliton pulse-duration-selectable source based onadiabatic compression in Raman amplifier

Raman amplified 10 ps soliton pulses generated directly from an electroabsorption modulator based source have been adiabatically compressed in a Raman fibre amplifier, giving pulse duration tunable sources of 10-1 ps at 10 GHz and average powers up to 650 mW, dependent on the magnitude of the amplification     

Pulse width tunable subpicosecond pulse generation from an activelymodelocked monolithic MQW laser/MQW electroabsorption modulator

Actively modelocked pulses are generated from a 1.59 μm MQW laser integrated with an MQW electroabsorption modulator driven at the monolithic cavity frequency. The pulse width is controlled from 39 ps to 0.55 ps by changing the inverse bias voltage applied to the electroabsorption modulator and by linear pulse compression using a fibre     

23 cm long Bi/sub 2/O/sub 3/-based EDFA for picosecond pulse amplification with 80 nm gain bandwidth

Amplification of a 1 ps pulse train in a 22.7 cm Bismuth oxide (Bi/sub 2/O/sub 3/)-based erbium doped fibre amplifier (EDFA) is reported. An amplification bandwidth of 80 nm, from 1520 to 1600 nm is demonstrated. Because of the short length, amplification of picosecond pulses is achieved without pulse broadening over a wide wavelength range.     

Generation of high-repetition-rate optical pulse using cascaded long-period fibre gratings

The generation of high-repetition-rate optical pulses using cascaded long-period fibre gratings is proposed. The pulse multiplication is realised by exploiting the difference in the propagation constant of the core and a cladding mode in a standard singlemode fibre. Two, four and eight times pulse multiplication have been successfully implemented with a minimum repetition period of 2.4 ps.     

A 250-MHz-2-GHz wide-range delay-locked loop

This paper describes a wide-range delay-locked loop (DLL) for a synchronous clocking which supports dynamic frequency scaling and dynamic voltage scaling. The DLL has wide operating range by using multiple phases from its delay line. A phase detector (PD) which combines linear and binary characteristics achieves low jitter and fast locking speed. A pulse reshaper makes output pulses of the phase detector have variable pulsewidth and variable voltage level to mitigate the static phase error due to the inherent mismatch of the charge pump. The DLL operates in the range from 250 MHz to 2 GHz. At 1 GHz operating frequency, RMS jitter and peak-to-peak jitter are 1.57 ps and 10.7 ps, respectively.