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.     

Multiwavelength fibre laser with wavelength selectable from 1590 to 1645 nm

A multiwavelength fibre laser with a semiconductor optical amplifier is reported. The lasing wavelength of the laser can be adjusted from 1590 to 1645 nm by adjusting the round-trip cavity loss. Simultaneous lasing of over 40 wavelengths with signal-to-noise ratio of over 40 dB was achieved from 1612 to 1645 nm.     

Wavelength switching of picosecond pulses in a self-seededFabry-Perot semiconductor laser with external fiber Bragg gratingcavities by optical injection

All-optical wavelength switching of single-mode picosecond pulses was demonstrated in an optically gain-switched Fabry-Perot semiconductor laser with self-seeding from two uniform fiber Bragg gratings (FBGs) or a linearly chirped FBG by injecting optical pulse trains with a peak power of ~1.0 mW at GHz repetition rates. Sidemode suppression ratio (SMSR) better than 17 dB was achieved in both wavelengths in the former case. Wavelength switching among three successive laser cavity modes was achieved in the latter case. A SMSR better than 15 dB was obtained at all three wavelengths. This laser has potential applications in remote optically controlled fiber sensors, such as temperature sensors     

Wavelength switching components for future photonic networks

This article provides a review of integrated laser and semiconductor optical amplifier components that have been configured to provide a variety of all-optical functions such as wavelength conversion, routing, signal regeneration, and add-drop multiplexing. The components have been devised so that they can be reliably and simply used within a multiwavelength network. The article introduces the components by outlining the current leading techniques for wavelength conversion using SOAs, namely by way of cross-gain modulation, cross-phase modulation, and four-wave mixing. The integrated SOA distributed feedback laser is then shown to provide excellent regeneration properties, not only overcoming fiber dispersion limitations but also polarization mode dispersion. Finally, the devices are shown to make possible a regenerative wavelength switching node where routing is achieved using a tunable laser to provide regenerative wavelength conversion followed by an arrayed waveguide router. This switch shows promise for use in future photonic packet switching architectures     

Ultrashort Pulse Amplification at 1080 nm With a Long-Wavelength InGaAs–GaAs Flared Amplifier

Pulses of 5 ps in duration have been amplified using a long-wavelength InGaAs-GaAs semiconductor optical amplifier containing a flared waveguide. The amplifier is seeded using short pulses emitted by a passively mode-locked semiconductor laser. Average output powers of 50 mW have been obtained at a center wavelength of 1080 nm for a drive current of 290 mA. Pulse compression yields durations as short as 520 fs and peak powers as high as 40 W. Perspectives for combining the semiconductor master oscillator power amplifier with Yb fiber amplifiers in a hybrid configuration are also briefly discussed.     

Optical bistability and set-reset operation of a Fabry-Perotsemiconductor laser amplifier with two detuned light injections

Optical bistability in a Fabry-Perot semiconductor laser amplifier when two optical inputs detuned from the resonant wavelength of a semiconductor laser amplifier are injected is discussed. A split branch is found in the optical output versus input characteristics in addition to conventional optical bistability behavior. It is shown analytically and experimentally that set and reset can be achieved in the optical output of the semiconductor laser amplifier for each wavelength by applying two detuned optical pulses and using the split branch     

SOA-pumped erbium-doped ASE fibre source with flattened spectrum and high power density

A spectrum-flattened two-stage amplified spontaneous emission (ASE) fibre source is proposed and experimentally demonstrated. The source is structured by an erbium-doped fibre simultaneously pumped by a 980 nm laser and a semiconductor optical amplifier (SOA) source. In the wavelength range of 1526?1563 nm, a spectrum ripple of ±0.5 dB and an average power density of 214 dBm/0.1 nm are achieved.     

Semiconductor laser diode optical amplifiers/gates in photonicpacket switching

In this paper, we will describe how semiconductor laser diode optical amplifiers/gates can be used in the photonic packet switching systems based on wavelength division multiplexed (WDM) techniques. First, we show that cross-gain modulation (XGM) can be suppressed when the device is used in the transparent condition of the waveguide material even when the input signal power exceeds +18 dBm. We then discuss an appropriate encoding for the optical signal. Experimental results show that high bit rate Manchester-encoding enables the use of semiconductor laser diode optical amplifiers/gates in the gain condition as well as the transparent condition. Finally, a new photonic packet receiver which utilizes a semiconductor laser diode optical amplifier as a packet power equalizer is proposed. This receiver accepts 17 dB power fluctuation at nanosecond speed for 10 Gb/s Manchester-encoded signal     

波长转换器的研究

讨论了基于半导体激光放大器的波长转换器，它是光交换块中的关键元件，也是未来通信系统中的关键元件。从理论上分析了各种半导体光放大器转换器的转换原理，并给出了它们的种种结构。     

Semiconductor laser amplifier as optical switching gate

The properties of a semiconductor laser amplifier as optical switching gate are investigated. Particular attention is paid to gain, contrast ratio, and switching time of the device. These properties are studied experimentally and theoretically with respect to the injection current, optical input power, and cavity resonances. The experimental arrangements and the theoretical method are described. As an example of the various applications of semiconductor laser amplifier gates, packet switching experiments with self-routing, employing cascaded switching gates, are reported. In a theoretical analysis the restrictions that the properties of semiconductor laser amplifier gates impose on a larger switching system consisting of many such gates are investigated     

Rayleigh scatter measurements of a 42 km single-mode fibre at 1.55 ?m wavelength using an LD and an LN2 cooled Ge-PIN detector

A 42 km single-mode fibre has been observed by an OTDR at 1.55 ?m wavelength utilising a semiconductor laser and a Ge-PIN photodiode cooled to 77 K with liquid nitrogen together with a feedback resistor of a transimpedance amplifier. The dark current and the thermal noise have been drastically decreased.     

Time slot interchanging using semiconductor laser amplifiers

A four-channel optical time slot interchange switching experiment operating at 2.5 Gbit/s is reported. The system is based on a parallel switch fabric incorporating semiconductor laser amplifier gates and fibre delay lines. A sensitivity penalty of 0.2 dB for straight through operation, and 0.7 dB for fully interchanged time slots was observed.<>     

基于三波长SLA的全光解复用器

工作在三波长状态下的SLA作为非线性元件,在光环形镜中实现OTDM信号的解复用,模拟计算表明,在保持光束功率为1W时,SLA恢复时间小于10ps,可从OTDM复用信号中提取出任一路信号,在控制脉冲功率为900mW时,带宽可达100GHz。     

Influence of carrier transport on performance of SLALOM with apolarization-independent MQW SLA

The switching performance of the semiconductor laser amplifier in a loop mirror (SLALOM) with a polarization-independent multiquantum-well SLA influenced by the carrier transport is discussed. It is shown that the switching window is polarization-dependent in the case of ultra-short pulses used as switching pulses because of the carrier transport effect between quantum wells. The influence of polarization can be suppressed by modifying the polarization state of local switching pulses     

Carrier-induced group-velocity dispersion and pulse compression in semiconductor laser amplifiers

The effect of gain dispersion on pulse amplification in semiconductor laser amplifiers is investigated theoretically. A novel phenomenon, referred to as carrier-induced group-velocity dispersion, is shown to influence considerably the amplified pulse. Chirped input pulses are predicted to be compressed in the presence of carrier-induced dispersion even when the amplifier operates far below saturation. The dependence of the compression factor on device parameters such as the pulse width, the amplifier gain, and the linewidth enhancement factor are studied using a simple analytic model. The results are important for optical communication systems as they imply that semiconductor laser amplifiers can be used to compensate simultaneously for the effects of both fibre loss and fibre dispersion when used as in-line amplifiers.<>     

Multiwavelength-switchable SOA-fibre ring laser using sampled Hi-Bi fibre grating

A novel multiwavelength-switchable laser based on a semiconductor optical amplifier (SOA) within a fibre ring cavity with a sampled high-birefringence fibre grating is proposed. Four channels with 0.8 nm spacing have been generated at room temperature and switched to other channels with 0.4 nm wavelength-shift by adjusting an inserted polariser. The laser can be used in hierarchical cross-connect WDM networks employing an interleaved waveband concept.     

基于游标原理的可调谐分布反射全光纤激光器

报道了一种新型全光纤离散可调谐分布反射(DBR)光纤激光器。光纤激光器为短腔结构,其有源区采用Er-Yb共掺单模光纤,有源光纤长度为6 cm。激光器采用两组级联光纤布拉格光栅(FBG)为反射腔镜,前腔镜各级联光纤布拉格光栅的布拉格波长间隔为1 nm,后腔镜为0.8 nm,利用游标原理,通过对前腔镜级联光纤布拉格光栅进行机械调谐,使前后腔镜各反射波长分别对准,实现了四个固定波长间隔为0.8 nm的离散调谐。这种光纤激光器具有波长调节准确,调谐速度快,成本低的优点,可用于作为多波长光纤传输系统的发射光源或系统检测光源,进一步增加级联光栅的组数可实现更大调谐范围。     

All-optical phase modulation in a traveling wave semiconductorlaser amplifier

A novel all-optical phase modulation and wavelength conversion has been demonstrated in a traveling wave semiconductor laser amplifier. Even though the optical gain modulation caused by the saturation effect in a traveling wave semiconductor laser amplifier is sensitive to the signal wavelength, the optically controlled phase modulation is relatively independent of the signal wavelength     

L-band erbium-doped fibre amplifier with clamped- and flattened-gain using FBG

A gain clamped long wavelength band erbium-doped fibre amplifier (L-band EDFA) based on a ring laser cavity is demonstrated using a fibre Bragg grating (FBG) at the output end of the amplifier. This new design provides a good gain clamping as well as a gain flattening. The gain is clamped at 16.9 dB with gain variation of less than 0.1 dB from input signal power of -40 to -18 dBm by setting the VOA=5 dB. Also, the amplifier has the flattest gain spectrum at VOA=5. The gain variation is less than 1.0 dB within the wavelength range from 1570 to 1600 nm. This gain clamped amplifier also can support a 12 channel WDM system.     

Low noise, all-optical gain controlled Er3+ doped fibreamplifier using asymmetric control laser cavity design

The authors demonstrate an Er³⁺ doped fibre amplifier with all-optical, automatic gain control and with near quantum limited, 1480 nm pumped noise performance. The amplifier gain is controlled by in-band laser action, and two design considerations are established for optimum noise performance: the control laser wavelength should be located in a region of high amplifier gain, and the laser cavity should be constructed to be as asymmetric as possible, ensuring minimum laser power at the signal input end of the amplifier