Multiwavelength erbium-doped fiber ring laser incorporating an SOA-based phase Modulator

A novel room-temperature multiwavelength erbium-doped fiber (EDF) laser is demonstrated. Stable multiwavelength lasing at room temperature is realized by incorporating a semiconductor optical amplifier (SOA)-based phase modulator in the laser cavity. The SOA is biased below the transparent point with a sinusoidal signal applied to achieve phase modulation, to suppress the homogenous line broadening of the EDF. Stable multiwavelength lasing with wavelengths up to 26 and wavelength spacing as small as 0.19 nm is demonstrated at room temperature.     

基于频移和偏振烧孔的多波长掺铒光纤激光器

为了研究能够在室温下实现稳定多波长输出的掺铒光纤激光器,采用了在激光谐振腔中引入正弦相位调制和偏振烧孔来抑制腔中模式竞争的方法。在线形谐振腔中,利用半导体光波导作为一个反射腔镜,并用正弦信号对其进行驱动。这样,半导体光波导可以等效成一个对光信号产生移频反馈效果的正弦相位调制器和一个诱使掺铒光纤中产生偏振烧孔的非线性相位延时器。通过实验,得到了10波长输出的稳定光谱。相邻波长间隔为0．32nm,功率谱比较平坦,起伏小于3dB。结果表明,相位调制和偏振烧孔的共同作用,可有效地抑制由于掺铒光纤的均匀展宽效应引起的模式竞争。     

掺镱光纤激光器的多波长振荡特性

利用Sagnac梳状滤波器,研究了环形腔掺镱光纤激光器(YDFL)在室温和77 K时的多波长振荡行为。结果表明,在室温和77 K时,掺镱光纤(YDF)均呈现明显的非均匀加宽效应,使得掺镱光纤激光器的起振波长数随抽运光功率的提高而增多。但在室温下,因均匀加宽效应强,掺镱光纤增益的非均匀加宽并不能补偿其内禀不平坦的增益谱,造成波长缺失现象,且当波长间隔减小至0.8 nm时,均匀加宽效应引起的波长竞争造成了多波长振荡的稳定性下降。而在77 K时,掺镱光纤非均匀加宽效应明显增强,在0.8 nm的波长间隔下,无波长缺失现象,将起振波长数增加到32个,且多波长振荡稳定。     

基于光纤拉锥及相位调制的可切换多波长掺铒光纤激光器

研究了一种全光纤可切换多波长掺铒光纤激光器。该激光器利用一段缠绕在压电陶瓷上的单模光纤作为正弦相位调制器以及基于光纤拉锥的马赫-曾德尔干涉仪作为梳状滤波器,抑制由于掺铒光纤的均匀展宽效应引起的模式竞争,从而避免了在室温下不稳定的单波长激射,实现了多波长掺铒光纤激光器的稳定输出。实验中观察到稳定的5个波长的同时激射,相邻波长间隔为0.804 nm。信噪比大于40 dB,3 dB带宽约为0.023 nm,中心5个波长输出功率的平坦度为14 dB。同时,激光器具有灵活的波长可切换特性,通过调整驱动信号和偏振控制器的状态,实现了单波长、双波长、三波长以及更多波长的输出。该激光器可应用于大容量波分复用系统和光纤传感。     

Multiwavelength $Q$-switched Laser by Incorporating a LiNbO$_{3}$ Phase Modulator in Fabry–PÉrot Cavity

In this letter, we present a simple and compact laser cavity that can be used for $Q$-switching and multiwavelength oscillation. It is shown that a LiNbO $_{3}$ phase modulator with relatively low driven voltage inserted into a Fabry–PÉrot cavity can act simultaneously as an effective component for suppressing the homogeneous line broadening, switching the $Q$ -value of the laser cavity, and a polarizer. Multiwavelength operation of Yb-doped fiber laser is achieved by phase modulation. $Q$-switching is achieved due to the residual intensity modulation of the phase modulator, and the pulse performance is also impacted by the phase modulation amplitude. Three stable wavelengths with identical wavelength spacing of 3.3 nm and pulsed laser of 0.2 $mu$J per pulse energy at the repetition rate of 55.8 kHz are demonstrated. The full-width at half-maximum pulse duration is of 2 $mu$s, and the polarization extinction ratio is $>$23 dB.      

Multiwavelength switchable SOA-fibre ring laser using digital micromirrors

A novel multiwavelength switchable SOA-fibre ring laser incorporating digital micromirrors is demonstrated. By controlling the states of micromirrors, the flexible allocation of the wavelength channels and the multiwavelength switching operations is achieved. Up to 12 wavelength channels with 0.8 nm spacing at room temperature are generated.     

正弦相位调制下多波长掺铒光纤激光器的研究

通过理论分析并实验验证了一种能在室温下实现稳定的掺铒光纤激光器(EDF)多波长输出的方法。通过在线形谐振腔中引入正弦相位调制器。抑制了由于掺铒光纤的均匀展宽效应引起的模式竞争，从而避免了在室温情况下不稳定的单波长激射。与此同时，线形谐振腔引起的空间烧孔效应也有利于抑制均匀展宽效应。通过取样光纤光栅(SBG)的选频作用，实验中观察到稳定的5个波长的同时激射，相邻波长间隔为0．8nm，符合ITU标准。     

室温下稳定工作的多波长掺铒光纤激光器

对多波长掺铒光纤激光器进行了实验研究。通过在环形腔掺铒光纤激光器中引入一个全光纤相位调制器,在双折射光纤长度约为4．1m时,实现了室温下16个波长的稳定输出,波长间隔为0．8nm,满足ITU信道标准。而且通过改变双折射光纤的长度,可实现相邻时长间隔的精确调节。激射波长线宽小于0．1nm。功率谱比较平坦,在近12nm的谱宽内功率起伏小于dB。     

A self-seeded tunable multiwavelength erbium-doped fiber ring laser with fiber bending scheme

A new tunable multiwavelength fiber laser is proposed. Such a laser contains a homogeneous and inhomogeneous broadening media, i.e., a Fabry–Perót laser diode and an erbium-doped fiber amplifier, in the laser cavity. The Fabry–Perót laser diode is used to obtain tunable multiwavelength lasing. By adjusting the injection current of the Fabry–Perót laser diode, emission at a single wavelength, dual wavelengths, triple wavelengths or quadruple wavelengths are obtained. The lasing wavelength is tuned by bending a section of fiber in the laser cavity. The tuning ranges for single wavelength lasing and dual wavelength lasing are 20 nm and 10 nm, respectively, while those for triple wavelength lasing and quadruple wavelength lasing are 7 nm and 3 nm, respectively.     

基于相移光栅的多波长掺铒光纤激光器的实验研究

提出了一种基于相移光栅(PSG)的多波长掺铒光纤激光器的结构。在该结构中,使用双相移点相移光栅作为波长选择器件,该光栅是在普通布拉格光栅上插入两个相移点而形成的。以980nm的激光二极管(LD)作为抽运源,通过调整偏振控制器(PC),在室温下得到了稳定的三波长激光输出。通过连续25min的观察,观测到输出波长的峰值波动范围小于0.6dB。研究了相移光栅激光器的温度特性,通过设置不同的温度(25℃～85℃),实现了此类基于相移光栅激光器的微调谐。该掺铒光纤激光器可同时输出多个稳定的波长,因此可应用于多波长干涉测量以及全光通信等领域中。     

基于相位调制和偏振烧孔的多波长掺铒光纤激光器

为了研究能够在室温下实现稳定多波长输出的掺铒光纤激光器,采用了在激光谐振腔中引入正弦相位调制和偏振烧孔来抑制腔中模式竞争的方法。在线形谐振腔中,利用半导体光波导作为一个反射腔镜,并用正弦信号对其进行驱动。这样,半导体光波导可以等效成两个器件：一个对光信号产生移频反馈效果的正弦相位调制器,和一个诱使掺铒光纤中产生偏振烧孔的非线性相位延时器。通过实验,得到了10波长输出的稳定光谱。相邻波长间隔为0.32nm,功率谱比较平坦,起伏小于3dB。结果表明,相位调制和偏振烧孔的共同作用,可以有效的抑制由于掺铒光纤的均匀展宽效应引起的模式竞争。     

Multiwavelength generation in a Raman fiber laser with sampled Bragg grating

Simultaneous continuous-wave multiwavelength operation of a Raman fiber laser is demonstrated with sampled Bragg grating (SBG) at room temperature. The characteristics of multiwavelength fiber ring laser can be easily controlled by adjusting the parameters of the SBG, including the sampling period and the sampling length. In the proposed fiber laser, stable four oscillating wavelengths with 100- and 50-GHz spacing has been achieved, respectively, as well as five oscillating ones with a wavelength spacing of only 25 GHz by varying the sampling period of the SBG.     

40-GHz mode-locked fiber-ring laser using a Mach-Zehnder interferometer with integrated SOAs

A 40-GHz mode-locked fiber-ring laser based on an optically controlled modulator is presented and analyzed in detail. The modulator is a monolithic InGaAsP-InP Mach-Zehnder interferometer with integrated semiconductor optical amplifiers, which allows optical pulse generation synchronized to an external optical clock pulse stream. The laser generates nearly transform-limited Gaussian pulses of 2.5-ps width and up to 9-mW mean output power with less than 130 fs of timing jitter, and it is wavelength tunable over more than 30 nm. The relationship between key laser parameters and the output pulse characteristics is analyzed experimentally and numerically. An improved cavity design permits the generation of shorter pulses of 1.0-ps width.     

Multiwavelength Erbium-Doped Fiber Laser Employing Cavity Loss Modulation

A novel and simple multiwavelength erbium-doped fiber laser is proposed and demonstrated. The combination of a polarization scrambler and a polarizer is employed to induce polarization-dependent-loss modulation. The loss modulation induced multiwavelength lasing by alleviating the mode competition caused by homogeneous gain broadening of the erbium-doped fiber. As a result, 11-wavelength lasing operation with wavelength spacing of 0.8 nm has been achieved. The output power distribution is quite uniform and the power fluctuation of each wavelength is smaller than 0.6 dB.     

Wavelength-tunable narrow-linewidth semiconductor fiber-ring laser

A passive sub-ring was inserted into a semiconductor fiber-ring laser as the Vernier configuration to enable stable lasing spectrum. Wavelength tuning over 20 nm and fine tuning of less than 0.0001 nm were obtained by rotating the polarization controller and adjusting the voltage on the phase modulator, respectively. A narrow linewidth of less than 10 kHz and a sidemode suppression ratio of higher than 35 dB were demonstrated with single longitudinal-mode operation     

Multiwavelength erbium-doped fiber ring laser employing Fabry–Perot etalon inside cavity operating in room temperature

In this investigation, we propose and demonstrate a simple and cost-effective erbium-doped fiber (EDF) ring laser using a Fabry–Perot etalon inside a linear cavity and employing the accurate fiber cavity length to satisfy the least common multiple number for generating multiwavelength in C-band at room temperature. Furthermore, the center wavelength of the lasing wavelength bands can be adjusted to 1541.02, 1551.32, and 1562.03 nm, respectively. The wavelength separation in each wavelength band is 0.34 nm. Moreover, the output stability of the multiwavelength laser has also been discussed and analyzed.     

Frequency locking of semiconductor laser using PSK modulated signal

A random PSK modulated signal generated with an optical waveguide phase modulator is used to obtain an error signal and lock the frequency of an AlGaAs semiconductor laser to the /sup 7/Rb D/sub 2/ line. The measured error signal is similar to that obtained with sinusoidal phase modulation under the same conditions. The technique could be applied to longer wavelength lasers and other types of laser that cannot be directly modulated such as fibre lasers.<>     

Tunable dual-wavelength actively mode-locked fiber laser with anF-P semiconductor modulator

A novel actively mode-locked fiber laser for generating dual-wavelength picosecond pulses is proposed by using a Fabry-Perot laser diode as the modulator in the ring cavity. A linear chirped fiber grating was used as a wavelength selector and produces temporal-spectral multiplexing of the pulses in the gain medium to reduce gain cross-saturation effects. About 2-GHz stable dual-wavelength pulses with a wavelength spacing of 0.92 nm at room temperature were experimentally demonstrated and the wavelengths could be tuned in a range of about 3 nm     

Uniform 90-channel multiwavelength InAs/InGaAsP quantum dot laser

A 93-channel multiwavelength laser with maximum channel intensity non-uniformity of 3.0 dB over a wavelength range from 1638 to 1646 nm was demonstrated on the basis of a single 4500 mum-long InAs/InGaAsP quantum dot Fabry-Perot cavity chip. All channels were stable because of inhomogeneous gain broadening due to statistically distributed sizes and geometries of self-assembled quantum dots     

Multiwavelength Raman fiber-ring laser based on tunable cascaded long-period fiber gratings

Multiwavelength Raman fiber lasers using intracavity tunable cascaded long-period fiber gratings (LPFGs) are discussed. The application of the cascaded LPFGs as a multichannel fiber filter for the multiple-wavelength generation is proposed and experimentally demonstrated. The characteristics of multiwavelength fiber-ring lasers can be controlled by changing the physical parameters of cascaded LPFGs such as the separation distance between the gratings, grating length, and number of gratings. The multiwavelength Raman fiber-ring laser with nine wavelength-division-multiplexing channels with 100-GHz spacing and 19 channels with 50-GHz spacing has been achieved by varying the physical parameters of cascaded LPFGs.