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.     

工作在L波段的多波长Er3 /Yb3 共掺光纤激光器

采用Er^3 ／Yb^3 共掺双包层光纤(EYDF)作为增益介质，利用一段标准的多模光纤作为空间梳状滤波器，于室温下实现了5个波长的稳定输出。通过调节偏振控制器的状态，可以实现对波长振荡个数和波长间隔的控制。腔中不加任何的稳定装置，在激光输出功率高于207mw时，仍能够得到多波长的稳定振荡，单一波长的线宽窄于0．15nm，边模抑制比大于32dB。通过优化单模光纤与多模光纤的熔接，选择更加合适的多模光纤，可实现更多波长个数的稳定的多波长输出。     

Stable and broad bandwidth multiwavelength fiber ring laser incorporating a highly nonlinear photonic crystal fiber

A stable and broad bandwidth multiwavelength fiber ring laser suitable for use in dense wavelength-division-multiplexing systems is demonstrated. A highly nonlinear photonic crystal fiber is inserted in the ring cavity to stabilize the power fluctuation and broaden the output spectrum. A thin-film Fabry-Pe/spl acute/rot etalon filter is used to get stable wavelength lasing. A Sagnac filter is employed to achieve uniform power distribution at each wavelength at the laser output. A laser with a power fluctuation about 0.1 dB in each wavelength within 20 min and with wavelength shift of less than 0.016 nm within 10 min is achieved. A stable 24-wavelength lasing operation with wavelength spacing of 0.8 nm within the 3-dB spectral range of 1573-1594 nm and signal-to-noise ratio better than 48 dB is observed experimentally.     

窄线宽多波长掺铒光纤激光器

在掺铒光纤线型的单模光纤腔中接续一段多模光纤 ,依靠多模光纤中导模的空间模式跳动与激光谐振腔中的偏振烧孔共同作用 ,实现了窄线宽多波长的同时激射。激射波长的 3d B线宽约为 0 .0 9nm ,波长间隔为 0 .6 8nm。     

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。     

A switchable dual-wavelength erbium-doped fiber laser based on Sagnac loop inserted with two FBGs

A novel switchable dual-wavelength erbium-doped fiber （EDF） laser is demonstrated. The wavelength selection ele- ment consists of two fiber Bragg gratings （FBGs）, a polarization controller （PC） and a 3 dB coupler forming a Sagnac loop inserted with two FBGs. We study the effect of coupling ratio on filtering performance in this paper. By adjusting PC, we can change the wavelength-dependent loss, and then using nonlinear polarization rotation effect to suppress the mode competition caused by the homogeneous broadening of EDF, we obtain single- and double-wavelength laser outputs. At room temperature, under 200 mW pump power, dual-wavelength laser is achieved, and the center wave- lengths are 1545.34 nm and 1548.20 nm, respectively. The peak power values are -13.36 dBm and -14.58 dBm, and side mode suppression ratios （SMSRs） are 41.10 dB and 39.88 dB, respectively. Within two hours, the maximum fluctuation of peak power is less than 0.7 dB, which shows that the demonstrated fiber laser is stable. Moreover, by adjusting PC, singel-wavelength laser output is obtained, the peak power is -6.27 dBm or -5.45 dBm, and SMSR is 40.03 dB or 39.96 dB at 1545.34 nm or 1548.20 nm, respectively.     

Optimization of the multiwavelength erbium-doped fiber laser in a unidirectional cavity without isolator

Highly uniform multiwavelength erbium-doped fiber ring laser with an intra-cavity sine phase modulator is demonstrated. The flat output spectrum is achieved by optimizing the cavity structure, modulation amplitude and frequency of the sine phase modulator. 15 lasing lines with wavelength spacing of 0.9 nm appear simultaneously and stably in power differences less than 2 dB and the side mode suppression ratio higher than 32 dB. In addition, the proposed cavity can support unidirectional operation without optical isolators. The output power difference of about 20 dB is realized between counterclockwise and clockwise direction, which is almost independent of the pump power and lasing wavelengths.     

A novel configuration for multiwavelength actively mode-lockedfiber lasers using cascaded fiber Bragg gratings

A novel scheme for multiwavelength and wavelength-switching operations in an actively mode locked fiber laser using a cascaded sequence of fiber Bragg gratings in the laser cavity is presented. In this scheme, the cavity lengths for all wavelengths selected by the gratings are intrinsically identical, Generation of simultaneous dual-wavelength picosecond pulses with a wavelength separation of 3.5 or 20.1 nm was demonstrated. The interchange between dual- and single-wavelength operations and wavelength switching from one single-wavelength to another were simply achieved by polarization adjustment     

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。     

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.     

双环内级联采样光栅的多波长锁模光纤激光器

为了实现多波长激光输出,提出了一种改进的多波长主动锁模光纤环形激光器,采用集成级联采样光纤光栅进入激光腔形成稳定的多种波长激光的方法,进行了理论分析和实验验证。结果表明,双环形腔结构对于所有波长激光,其腔长度是一致的,从而可以用相同的锁模信号实现所有波长的同步锁模。实验中光纤环形激光器成功实现了以1.6nm为间隔的波长多达14个;它的输出功率大于0dBm,边模抑制比约30dB,最高模式锁模频率为1.05GHz,输出脉冲序列的脉宽是216ps。这一结果对光纤传输系统设计是有帮助的。     

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.     

超宽光谱类噪声脉冲光纤激光器

报道了一种全光纤超宽带光谱的类噪声脉冲锁模光纤激光器。为了加宽锁模光谱,利用腔内色散管理和非线性技术,使在58m腔内具有小的反常色散,平均色散系数为0.12 ps/nm/km。实验获得了超过1300nm--1750nm超宽带光谱锁模类噪声脉冲,光谱20-dB带宽达到362nm,3-dB带宽达到102nm。类噪声脉冲的光谱宽度远超过掺铒光纤的增益带宽。     

Stable multiwavelength dispersion-tuned actively mode-locked erbium-doped fiber ring laser using nonlinear polarization rotation

We demonstrate a stable multiwavelength actively mode-locked erbium-doped fiber laser at 10 GHz based on a dispersion cavity and nonlinear polarization rotation (NPR) effect. The dispersion cavity allows simultaneous multiple wavelengths to satisfy the round-trip condition and smooth wavelength tuning, while the NPR ensures the stable operation and supermode noise suppression. A simple model is developed to explore the optimal setting of the cavity. Simultaneous dual- and five-wavelength operation is experimentally investigated.     

Multiwavelength fiber ring laser source based on a delayed interferometer

A multiwavelength fiber laser source is demonstrated with a semiconductor optical amplifier as the gain medium. A delayed interferometer is incorporated in the ring cavity serving as a comb-like multichannel filter. A stable 75-wavelength simultaneous operation spaced at 40 GHz with the extinction ratio of 40 dB is achieved. By tuning the cavity loss, the center wavelength of the generated lasing waveband could be varied by as much as 20 nm.     

利用非线性偏振旋转效应的可调谐多波长光纤激光器

提出了一种基于非线性偏振旋转(NPR)效应的可调谐多波长掺铒光纤(EDF)激光器,非线性偏振旋转诱导的强度相关非均匀损耗有效地抑制了均匀加宽增益介质掺铒光纤中的模式竞争,使光纤激光器在室温下产生稳定的多波长输出。其中利用保偏光纤和偏振相关隔离器组成的等效Lyot 双折射光纤滤波器作为波长选择器件,该滤波器可以通过选择合适的双折射光纤长度改变波长间隔,调节偏振控制器改变偏振态实现对波长的精密调谐。实验采用10 m长的保偏光纤(PMF),得到了波长间隔为0.35 nm、最多17个波长的稳定激光输出,并且实现了输出波长在4 nm范围内的连续可调谐。分别采用10:90、30:70和50:50的输出耦合器,激光信号分别从10%、30%和50%的端口输出,得到了最多17、14和13个波长的输出,其波长功率浮动分别为13 dB、10 dB和7 dB,另外,其最大输出功率分别为-7 dBm、-3 dBm和0 dBm。实验结果表明,输出耦合器输出端比例越大,输出波长就越少,各波长激光输出功率越平坦,且输出功率越高。     

46 × 2.5 GHz Mode-Locked Erbium-Doped Fiber Laser With 25-GHz Spacing

We demonstrate a mode-locked, multiwavelength erbium-doped fiber laser at 2.5 GHz with 25-GHz channel spacing and that is wavelength tunable from 1545 to 1558 nm. Stable, room-temperature operation is obtained by exploiting four-wave mixing in a length of highly nonlinear fiber. At a central wavelength of 1549.5 nm, we obtain 30 wavelengths within 3 dB and 46 wavelengths within 6 dB; the full-width at half-maximum of the envelope is 85 ps.     

A nonlinear optical loop mirror-based linear cavity swit- chable multi-wavelength erbium-doped fiber laser

A nonlinear optical loop mirror (NOLM)-based linear cavity switchable multi-wavelength erbium-doped fiber (EDF) laser is proposed and experimentally demonstrated. Due to the characteristics of the intensity-dependent transmissivity, the NOLM can effectively mitigate the mode competition of the homogenous broadening gain medium, so that the multi-wavelength lasing can be achieved at room temperature. By adjusting the states of the polarization controllers (PCs), the number of the lasing wavelengths in the proposed laser can be adjusted flexibly from 11 to 13 with a wavelength spacing of 0.4 nm around the wavelength of 1 530 nm.     

Multiwavelength picosecond pulses generated from a self-seededFabry-Perot laser diode with a fiber external cavity using fiber Bragggratings

A novel scheme for generating multiwavelength short pulses using fiber Bragg gratings (FBGs) was demonstrated. In this scheme the external cavity length for all wavelengths selected by the gratings is intrinsically identical and the FBGs can be cascaded into the external cavity. Simultaneous generation of 1-GHz dual-wavelength short pulses with a wavelength separation of 1.6 or 18 nm was demonstrated. A sidemode suppression ratio (SMSR) better than 30 or 25 dB was achieved at both wavelengths in the former and latter cases respectively. Three-wavelength 1-GHz ps pulses with a SMSR better than 25 dB at all three wavelengths were also successfully generated     

Multiwavelength erbium-doped fiber lasers with active overlapping linear cavities

Multiwavelength oscillations in erbium-doped fiber (EDF) lasers with active overlapping linear cavities are investigated in detail. The laser can be designed to produce multiwavelength oscillations in the C-band and in the L-band. With a C-band three-wavelength laser, experiments show that the output powers of the lasing lines increase linearly or piecewise linearly with pump input. Any one lasing wavelength can be tuned over several nanometers depending on the gain tilt in the vicinity of the lasing wavelength while multiwavelength oscillation is still being maintained. The output power of any specific lasing line can be adjusted by suitably designing the EDF sections. This property also allows the laser to operate in multiwavelength switching mode. The laser exhibits a novel multiwavelength optical bistable behavior in the L-band. With an L-band dual-wavelength laser, the bistable input-output hysteresis behaviors of the two L-band wavelengths evolve in antiphase with respect to each other. The width of the bistable region has been increased to several tens of mW. It can be controlled and adjusted by the cavity loss and the EDF length. It is found that simultaneous L-band dual-wavelength oscillations can be obtained when part of the EDF, which functions as a saturable absorber, has been bleached. Moreover, simultaneous multiwavelength oscillations in both C-band and L-band have also been successfully demonstrated with the laser.