Multiple-Output Fiber-Ring Lasers and Amplifiers in a Hybrid CATV and ADSL Broadcasting Optical Fiber Communication System

In this article we propose two kinds of new fiber ring structure with a semiconductor optical amplifier. The first structure is a one-fiber-ring amplifier with an 8 × 8 fiber coupler and a semiconductor optical amplifier (SOA). The second fiber ring structure is a two-fiber-ring laser including an 8 × 8 fiber coupler, a 2 × 2 E/O modulator, and an SOA. The 14-output spectra of the fiber laser are measured. The gain coefficients of each port of the multiple-output-fiber-ring amplifiers are also measured. We apply these two kinds of fiber ring structures in a hybrid CATV and ADSL broadcasting optical fiber communication system. This application can develop a broadcasting system with large coverage area without using many laser diodes and optical amplifiers. The performance of such a system is also analyzed in this article.     

Multiple-Output Fiber-Ring Lasers and Amplifiers in a Hybrid CATV and ADSL Broadcasting Optical Fiber Communication System

In this article we propose two kinds of new fiber ring structure with a semiconductor optical amplifier. The first structure is a one-fiber-ring amplifier with an 8 × 8 fiber coupler and a semiconductor optical amplifier (SOA). The second fiber ring structure is a two-fiber-ring laser including an 8 × 8 fiber coupler, a 2 × 2 E/O modulator, and an SOA. The 14-output spectra of the fiber laser are measured. The gain coefficients of each port of the multiple-output-fiber-ring amplifiers are also measured. We apply these two kinds of fiber ring structures in a hybrid CATV and ADSL broadcasting optical fiber communication system. This application can develop a broadcasting system with large coverage area without using many laser diodes and optical amplifiers. The performance of such a system is also analyzed in this article.     

SOA-fiber ring laser and its application to electric field sensing in frequency domain

We have developed a novel optical fiber ring laser using a semiconductor optical amplifier (SOA) as the gain medium, and taking advantage of polarization anisotropy of its gain. The laser can control the oscillation frequency difference between two counterpropagating lights by incorporating a birefringent medium into the ring resonator. Since the frequency difference is proportional to the birefringence, it can be measured to detect the beat frequency generated by combining two counterpropagating lights and the laser can be applied to an optical fiber sensor whose detecting signal is in frequency domain. Electric field sensor was demonstrated with a lithium niobate crystal as a sensing probe.     

40-GHz wavelength tunable mode-locked SOA-based fiber laser with 40-nm tuning range

A 40-GHz wavelength tunable mode-locked fiber ring laser based on cross-gain modulation in a semiconductor optical amplifier (SOA) is presented. Pulse trains with a pulse width of 10.5 ps at 40-GHz repetition frequency are obtained. The laser operates with almost 40-nm tuning range. The relationship between the key laser parameters and the output pulse characteristics is analyzed experimentally.     

Tunable 19 × 10 GHz L-band FP-SOA based multi-wavelength mode-locked fiber laser

We present a multi-wavelength mode-locked fiber ring laser incorporating a semiconductor optical amplifier (SOA) and a Fabry-Perot semiconductor optical amplifier (FP-SOA). Because the gain of the SOA is depleted by an external injection optical signal, the SOA acts as a loss modulator. The FP-SOA serves as a tunable comb filter. The presented laser source can generate 19 synchronized wavelength channels with the extinction ratio of about 21 dB, each mode-locked at 10 GHz, and mode-locked pulse width is about 40 ps. Oscillation wavelengths band can be tuned by adjusting the bias current of the SOA, and wavelength spacing also can be changed by using a tunable optical delay line (ODL) or a temperature controller. The polarization-insensitive devices ensure that the output power is rather stable. This fiber laser has potential applications in longer waveband (L-band) within the low-attenuation window.     

超宽带可调谐SOA四波混频波长变换器的实验研究

基于半导体光放大器(SOA)光纤环形激光器中的双泵浦四波混频效应,构成超宽带并且完全透明的波长变换器,成功实现1550nm窗口2.5Gb/s信号的可调谐波长变换,变换效率在50nm范围内保持基本平坦,同时测出了SOA增益和自发辐射(ASE)噪音功率的关系.实验结果表明,在一定限制条件下,提高泵浦功率可以提高变换信号的信噪比.     

Tunable single-longitudinal-mode SOA-based fiber laser based on the spectral narrowing effect in a dispersion-shifted fiber

A tunable single-longitudinal-mode(SLM) semiconductor optical amplifier(SOA)-based fiber laser based on a dispersion-shifted fiber(DSF) is proposed and successfully demonstrated. SLM operation is obtained due to the spectral narrowing effect resulting from inverse four-wave mixing in a DSF. A tunable optical filter performs wavelength selection function. By inserting a length of DSF in the laser cavity, SLM lasing can possibly be obtained when laser oscillation is stably established after traveling through the DSF many roundtrips. Stable tunable SLM oscillation with a signal-to-noise ratio as high as 65 dB over a wavelength range of about 35 nm is achieved experimentally, and each spectral linewidth is less than 6.5 kHz.     

Dual-frequency Brillouin fiber laser for optical generation of tunable low-noise radio frequency/microwave frequency

We demonstrate a new approach, i.e., a cw dual-frequency Brillouin fiber laser pumped by two independent single-frequency Er-doped fiber lasers, for the generation of tunable low-noise rf/microwave optical signals. Its inherent features of both linewidth narrowing effect in a Brillouin fiber cavity and common mode noise cancellation between two laser modes sharing a common cavity allow us to achieve high frequency stability without using a supercavity. Beat frequency of the dual-frequency Brillouin fiber laser can be tuned from tens of megahertz up to 100 GHz by thermally tuning the wavelengths of the two pump lasers with tuning sensitivity of approximately 1.4 GHz/ degrees C. Allan variance measurements show the beat signals have the hertz-level frequency stability.     

Stable wavelength tunable fiber ring laser for true-time delay system

In this paper, we propose and experimentally demonstrate a novel wavelength tunable fiber ring laser source for a photonic beamforming system to control phased-array antenna. In this fabrication, a Sagnac loop composed of a polarization-maintaining (PM) coupler and a piece of high-birefringence (Hi-Bi) PM fiber is acted as a comb filter to make the frequency spacing equal. The wavelength of the output signal is controlled by the tunable filter outside the Sagnac loop. The intensities of the output signals with different wavelengths increased or decreased at the same frequency spacing are equal. A five-channel true-time delay system consisting of this tunable fiber source and five grating delay lines for discrete beamsteering has been demonstrated. In the experiment, the output signals of the tunable fiber ring with the equal frequency spacing have the same intensity of about 5.9 dBm and the same high signal to noise ratio (SNR) of 40 dB. If the tunable filter in this laser is replaced by a micro-electro-mechanical systems (MEMS) tunable filter, the speed of switching wavelength will increase rapidly.     

Wavelength-spacing continuously tunable multi-wavelength SOA-fiber ring laser based on Mach–Zehnder interferometer

A Mach–Zehnder interferometer (MZI) which is used as a wavelength-spacing tunable comb filter in a fiber ring laser is built by employing an optical variable delay line (OVDL). Stable multi-wavelength semiconductor optical amplifier (SOA)-fiber ring laser based on an SOA and the MZI comb filter is achieved. Wavelength spacing can be continuously tuned by adjusting the OVDL and, as an example, multi-wavelength lasing with the wavelength spacing of 0.4, 0.8, or 1.6 nm is demonstrated. The output of the proposed multi-wavelength SOA-fiber ring laser is quite stable at room temperature and the output spectrum can be adjusted by controlling the bias current of the SOA.     

波长可调谐超短光脉冲的简便高质的生成技术

提出了一种以处于增益开关调制状态下的法布里珀罗(Fabry-Pérot)半导体激光器作为光源,采用简单的自激注入锁定方式,以生成波长可调谐的超短光脉冲的实验系统。该实验装置中,激光器的外腔包括两个串联在一起的布拉格光纤光栅,一个掺铒光纤放大器(EDFA),一个光耦合器和两个环行器,其作用是选模,以及增强并控制反馈回激光器内腔的光强。该实验系统简单而高效,在24nm的波长调谐范围内获得了边模抑制比高于40dB的单模光脉冲输出;而在1521.8nm和1550.0nm之间28.2nm的波长调谐范围内,边模抑制比高于35dB。所得到的各个单波长激光脉冲的时域半峰全宽为140~260ps,各个脉冲的光谱半峰全宽皆为0.1nm。     

Tunable 12×10 GHz mode-locked semiconductor fiber laser incorporating a Mach-Zehnder interferometer filter

A stable multiwavelength mode-locked semiconductor fiber ring laser incorporating a fiber Mach-Zehnder interferometer (MZI) filter was proposed and experimentally demonstrated. A semiconductor optical amplifier (SOA) serves as an optically controlled mode-locking element due to gain exhaustion caused by external injected optical pulses. Another SOA severs as a constant-gain medium. A fiber MZI filter with a temperature control is incorporated into the fiber ring cavity to acquire a stable and tunable multiwavelength oscillation. Twelve wavelengths are synchronously mode-locked at 10 GHz, pulse width of mode-locked pulse are about 30 ps. Proposed multiwavelength mode-locked semiconductor fiber ring laser has some distinct advantages, such as simple and compact structure, easy integration, convenient tuning, good stability, potential high repetition rate operating, which has potential application in the future WDM communication system.     

基于DFB激光器的光学微波信号的产生

采用量子阱混杂的材料集成技术制备并联分布反馈激光器和Y形波导耦合器集成的新型光电器件.两个并联分布反馈激光器的激射模式在频率上稍有差别,这两束不同频率的激光在Y形波导耦合器拍频产生光学微波信号.分别独立调节注入到两个激光器的电流大小,可以得到从13 GHz到42 GHz连续可调的光学微波信号. 关键词： 光学微波信号生成 分布反馈激光器 Y形波导 拍频     

Broadband Brillouin slow light with multiple-longitudinal-mode,tunable pump

We propose and demonstrate broadband Brillouin slow light using a multiple-longitudinal-mode tunable fiber laser as Brillouin pump. A tunable broadband Brillouin pump with a tuning range from 1 520 to 1 555 nm is generated using a fiber ring laser with a semiconductor optical amplifier (SOA) as its gain medium. The pump spectrum consists of a large number of longitudinal modes separated by 6 MHz. The 3-dB bandwidth is about 11.5 GHz, and its fluctuation is less than 100 MHz within the tuning range. An 8-Gb/s data signal can be delayed by up to 83.0 ps (bit error rate < 10 9) at 17-dBm pump power.     

A photonic approach for microwave/millimeter-wave frequency measurement using stimulated brillouin scattering in single mode fiber

A photonic approach for microwave/millimeter-wave (MMW) frequency measurement is proposed and demonstrated based on stimulated Brillouin scattering (SBS) of a 20-km standard single mode fiber (SSMF). After the MMW signal is modulated to a laser source with two sidebands using optical carrier suppression (OCS) modulation, its frequency can be easily measured by monitoring the SBS-induced amplification with a power meter. Due to the 1-pm resolution of a tunable pump laser source, a frequency measurement range of 1–40 GHz is demonstrated in our experiment with a frequency resolution of 125 MHz. We believe the frequency measurement range can be further extended to satisfy photonic radar front-end processing application.     

基于单端半导体光放大器的可调谐超短光脉冲源理论与实验研究

超短光脉冲源是光时分复用(OTDM)系统中的关键器件.提出了一种基于单端半导体光放大器(SOA)的注入型主动锁模光纤激光器产生超短光脉冲的方案，建立了该方案的理论模型.实验实现了高消光比稳定的重复频率10—40GHz皮秒级光脉冲的输出，输出波长在30nm范围内连续可调. 关键词： 超短光脉冲 单端半导体光放大器 主动锁模     

High power tunable picosecond green laser pulse generation by frequency doubling of an Yb-doped fiber power amplifier seeded by a gain switch laser diode

A compact tunable high power picosecond green laser pulse source based on frequency doubling of an Yb-doped fiber amplifier seeded by a gain switch laser diode has been developed. The fiber amplifier generates the picosecond infrared pulses with average power of 10.3 W, repetition rate of 1 MHz, pulse duration of 150 ps, and tunable range of 20 nm around 1064 nm. For underwater use, the tunable output infrared pulses are frequency doubled into picosecond green laser pulses, which can be tuned from 527 to 537 nm with average power of more than 1.1 W, corresponding to an overall conversion efficiency of 10.7% by a BBO nonlinear crystal. This kind of laser source will have potential application for underwater optical communication.     

塑料光纤双锥与半球腔的活动耦合效应

报道了用氮氖激光实现的塑料光纤双锥与介质半球(称半球腔)之间的活动耦合效应。测量了光纤双锥的发射效率，并测量了锥腔耦合效率与半球腔的表面积、锥腔距离之间的关系。根据这种效应，可以制成塑料光纤活动耦合器；如果再加上调谐滤波器，可制成适合塑料光纤通信网用的信号上下载装置。     

A new approach of parallel data transmission through optical waveguide with SOA based frequency encoding/decoding technique

Semiconductor optical amplifier (SOA) is a well known non-linear device which can exhibit Tera Hertz switching speed of operation. SOA based switching, therefore, has wide application in fiber optic communication. Here in this communication the authors propose a new concept of frequency encoded parallel data transmission with SOA for optical communication. To achieve the transmission SOA is suggested for the generation of frequency encoded/decoded parallel data. It converts initially an intensity encoded optical data to frequency encoded one; whereas at the receiving end it again returns the intensity encoded data from frequency encoded one.     

A pump power controlled 1,060 nm multiwavelength fiber ring laser using nonlinear polarization rotation of SOA

We propose and experimentally demonstrate a both channel spacing and wavelength-tunable 1,060 nm multiwavelength fiber laser using nonlinear polarization rotation of semiconductor optical amplifier (SOA). The SOA in the cavity can not only provide the gain but also generate a pump power controlled phase-shift between two orthogonal linear states of polarization. The experimental result shows that the fast and continuous wavelength tuning is achieved with external light injection, while the channel spacing of the multiwavelength laser can be varied by adjusting the length of polarization maintaining fiber. When an external laser source with 13 dBm power is injected into the SOA as a control pump, optically tunable operation of up to 20 wavelength channels, from 1,042 to 1,058 nm, with a wavelength spacing of 0.8 nm has been demonstrated with the signal-to-spontaneous-noise ratio over 40 dB at room temperature. The lasers are stable with a maximum power fluctuation per channel of less than 0.5 dB during 2-h test.