Picosecond pulse generation with 1.5 /spl mu/m passively modelocked surface-emitting semiconductor laser

The authors report the first demonstration of an optically pumped passively modelocked surface-emitting semiconductor laser operating in the 1.5 /spl mu/m region. The modelocked laser emits pulses of 6.5 ps full width at half maximum duration with an average power of 13.5 mW at a fundamental repetition rate of 1.342 GHz. The peak power was 1.6 W.     

A broad-band millimeter-wave optical modulator using a passively modelocked semiconductor laser with phase noise compensation

A new and simple technique to produce efficient optical modulation at millimeter-wave frequencies by compensating for the phase noise of a 0.85-/spl mu/m passively modelocked semiconductor laser is presented. The passively modelocked laser is intensity modulated with the electrically mixed product of its phase noise and the millimeter-wave information signal. One of the resulting sidebands to the modelocked note is identical to the millimeter-wave frequency information because of the cancellation of the phase noise of the modelocked signal. A carrier-to-noise ratio (CNR) of 87 dBc/Hz at 41.9 GHz is demonstrated and it is shown that optical modulation at subcarrier frequencies up to 100 GHz and a CNR of 120 dBc/Hz is possible.     

Passive modelocking of InGaAsP/InP laser diode over wide operating temperature range

The passive modelocked operation of an InGaAsP/InP laser diode, with a novel design of adaptable saturable absorber, up to an operating temperature of 75/spl deg/C, is reported. To the authors' best knowledge, this is the first demonstration of high-temperature operation of a passively modelocked laser diode. The effect of the operating temperature on the operating frequency and the tuning range is described.     

All optical clock recovery at bit rates up to 40 Gbit/s

All-optical clock recovery at bit rates up to 40 Gbit/s using a modelocked fibre ring laser is demonstrated. The configuration simultaneously performs timing extraction and pulse reshaping to give a continuous stream of closely transform limited picosecond duration pulses.<>     

45 GHz self-pulsation with narrow linewidth in quantum dot Fabry-Perot semiconductor lasers at 1.5 /spl mu/m

Self-pulsation at 45 GHz repetition frequency has been demonstrated in 1.5 /spl mu/m monolithic single-section quantum dot Fabry-Perot semiconductor lasers without saturable absorber. The mode-beating exhibits a narrow linewidth below 100 kHz, demonstrating high phase correlation between these modes. Such modelocked lasers open ways to low timing-jitter components for clock recovery or millimetre-wave generation in wireless transmission applications.     

Subpicosecond pulse generation at 134 GHz and low radiofrequency spectral linewidth in quantum dash-based Fabry-Perot lasers emitting at 1.5 /spl mu/m

Passive modelocking in one-section monolithic semiconductor laser diodes based on a quantum dash active layer at very high repetition rate (>40 GHz), in the 1.5 /spl mu/m window, is demonstrated. 800 fs pulse generation, without any pulse compression scheme, at 134 GHz, is reported. A 50 kHz linewidth of the radiofrequency (RF) spectrum at 42 GHz is also demonstrated, the lowest value reported for any semiconductor passively modelocked laser.     

Sub-100 fs Kerr lens modelocked Cr4+:YAG laser

Sub-100 fs pulse generation from a Kerr lens modelocked Cr⁴⁺ :YAG laser has been demonstrated for the first time, yielding femtosecond pulses tunable from 1.49 to 1.56 μm with pulses as short as 90 fs obtained at 1.53 μm     

Compact fully fibre integrated source of 100 fs pulses at 1.1 /spl mu/m based on compression in holey fibre

A simple, compact, fully fibre integrated source of /spl sim/100 fs pulses at a wavelength of 1.1 /spl mu/m is reported. 4 ps pulses at 1063 nm from a modelocked fibre laser were amplified to 23 mW in a ytterbium-doped fibre amplifier and subsequently propagated through 62 m of holey fibre with a zero dispersion wavelength at 1040 nm. Soliton formation, breakup and self frequency shift resulted in the formation of /spl sim/100 fs pulses at 1.1 /spl mu/m. Wavelength tunability from 1113 to 1220 nm is demonstrated.     

30 Gbit/s downstream capacity of cost-effective colourless WDM-PON based on injection-locked Fabry-Perot lasers

A 100 GHz spaced comb, generated by a quantum dash passively modelocked laser, is used as a low-noise coherent seeding source for the colourless wavelength-division-multiplexed passive optical network based on injection-locked Fabry-Pe rot laser diodes. Error-free downstream transmission over 25 km singlemode fibre of 12 WDM channels at 2.5 Gbit/s with 100 GHz channel spacing is experimentally demonstrated.     

77 GHz soliton modelocked Nd:YVO4 laser

An Nd:YVO₄ laser which was passively modelocked at the very high repetition rate of ~77 GHz, using a semiconductor saturable absorber mirror (SESAM), is demonstrated. The soliton-like pulses are well separated in time and their duration is 2.7 ps. The required negative dispersion is introduced by a GTI-like structure, which is formed by the gain medium and the SESAM     

Tunable 4/spl times/10 GHz optically modelocked semiconductor fibre laser

A wavelength-tunable 4/spl times/10 GHz optically modelocked semiconductor fibre ring laser is demonstrated. A semiconductor optical amplifier (SOA) is used as a gain medium and optically controlled mode-locking element, in addition to four superimposed linearly chirped fibre Bragg gratings to provide tunable, multi-wavelength operation. The four wavelengths can be tuned simultaneously with constant wavelength separation by changing the modulation frequency.     

4.5 Gbit/s modelocked extended-cavity laser with a monolithically integrated electroabsorption modulator

An electroabsorption modulator has been monolithically integrated with an extended-cavity laser, which incorporates a Bragg reflector. Actively modelocked at the fundamental cavity resonance frequency of 4.5 GHz, the laser provides a train of 6.3 ps pulses with a centre wavelength of 1544 nm onto which data is encoded by the modulator. This 4.5 Gbit/s single-chip transmitter is suitable for systems employing short optical pulses.<>     

Diode-pumped femtosecond Yb:NaY(WO/sub 4/)/sub 2/

Pulses as short as 97 fs for an average power of 70 mW were obtained directly from a SESAM modelocked diode pumped laser based on the tetragonal NaY(WO₄)₂, a locally disordered double tungstate, doped with Yb. An extracavity prism pair helped to reduce the pulse duration to 90 fs with a corresponding time-bandwidth product of 0.321.     

160 Gbit/s soliton data transmission over 200 km

Polarisation- and time-domain-multiplexed 160 Gbit/s soliton signals have been successfully transmitted over 200 km for the first time. The soliton source was a 10 GHz regeneratively modelocked fibre laser and a planar lightwave circuit was used for optical multiplexing. The soliton pulse width was ~1.5 ps. A polariser and a nonlinear loop mirror were used for demultiplexing from 160 to 10 Gbit/s     

Highly efficient femtosecond Yb:KYW laser pumped by single narrow-stripe laser diode

A highly efficient and low threshold passively modelocked femtosecond Yb:KYW laser pumped by an InGaAs narrow-stripe laser diode is demonstrated. Near-transform limited pulses of 123 fs at 1047 nm were produced at an average modelocked power of 107 mW for only 308 mW of incident pump power. An optical-to-optical conversion efficiency of 35% was achieved and the corresponding electrical-to-optical efficiency exceeded 14%.     

Noise in fundamental and harmonic modelocked semiconductor lasers: experiments and simulations

Electric-field correlation measurements of fundamental and harmonic modelocked external cavity semiconductor lasers are presented. Based on these results, an empirical model of a harmonic modelocked pulsetrain is constructed. Using this model, the equivalence between the time-interleaved pulsetrains picture and the supermode picture of a harmonic modelocked pulsetrain is shown. Simulations based on the model are presented showing the key characteristics of modelocked pulsetrains in radio frequency (RF) and optical domains. The fundamental relationship between longitudinal mode linewidth and RF phase-noise corner frequency is delineated. The generated results point to fundamental limitations in timing jitter in modelocked lasers.     

高重复率全光纤被动锁模飞秒激光产生研究

报道了高重复频率全光纤被动锁模飞秒激光产生的实验研究,采用全光纤环形腔结构和非线性偏振旋转可饱和吸收被动锁模机理实现了100MHz级掺铒光纤锁模飞秒激光的稳定运转,最高重复频率为99.91MHz,光谱带宽为25nm,中心波长为1570nm,脉宽最短为194fs,实验同时研究了在不同重复频率下的全光纤被动锁模激光器运转动力学特性。研究为高重复频率飞秒光纤激光器在光频梳产生技术中的应用提供了高集成、高稳定超快光源技术途径。     

Controlled amplifier modelocked Er/sup 3+/ fibre ring laser

An erbium-doped fibre ring has been actively modelocked with an InGaAsP semiconductor amplifier employed as a modulator. Pulses having durations <4ps and peak powers of approximately 2 W around 1536 nm have been generated at a repetition frequency of 612 MHz by this new technique of controlled-amplifier modelocking (CAM).<>     

100 Gbit/s, 50 km, and nonrepeated optical transmission employing all-optical multi/demultiplexing and PLL timing extraction

A 16*6.3 Gbit/s, time-and-polarisation division multiplexed optical signal is successfully transmitted through a 50 km dispersion shifted singlemode fibre employing all-optical multi/demultiplexing. A 6.3 GHz timing clock is directly extracted from the multiplexed 100 Gbit/s optical signal by a phase locked loop (PLL) using a travelling-wave laser diode amplifier. A wavelength-tunable modelocked Er/sup 3+/-fibre ring laser and a planar-lightwave-circuit time division multiplexer are newly developed for this experiment.<>     

利用非线性反射镜锁模激光器的动力学过程分析

本文报导了对基于一种新型非线性反射镜的被动锁模激光器的动力学过程进行的研究.结果指出,该锁模过程始终存在于一种动态平衡中.最后,文中给出了该锁模激光器的输出脉宽的具体表达式.