CW-pumped polarization-maintaining Brillouin fiber ring laser: II. Active mode-locking by phase modulation

Stimulated Brillouin backscattering in a cw-pumped long optical polarization-maintaining fiber ring cavity excites spontaneous stable mode-locking. But the shortest pulses allowed by the Brillouin gain bandwidth imply an active mode-locking, which we have achieved by using a phase modulator inside the ring. The experiment is carried out in the infrared at 1.319 μm, and in narrow frequency domains, close to N integer multiples of the ring FSR, we observe two type of mode-locking: either a maximum compression of the Brillouin solitons, or a stable splitting into N equally spaced pulses. Case N = 3 is more detailed. Experiment implies a slight polarization modulation by the phase modulation. Simulations carried out through the coherent three-wave model are in very good agreement for both mode-locking mechanisms. Introduction of a small amplitude modulation together with the intra-cavity phase modulation satisfactorily explains the stable splitting domain as well as the compression domain.     

L-band erbium-doped fiber laser with polarization-maintaining ring cavity

A new, simple and efficient L-band erbium-doped fiber (EDF) laser with polarization-maintaining ring cavity is proposed and experimentally demonstrated. The laser offers the unique advantage of being a polarization-maintaining lasing, which meets the requirement of external electronic-optical intensity modulation for DWDM communication and interferometric fiber sensors. Theory has been established. Experimental results are given to show that the laser has long-term stability over a couple of hours with 35 dB signal-to-noise ratio at 1598.644 nm and tunable from 1572.167 to 1608.480 nm.     

A high-efficiency Brillouin fiber ring laser

A high-efficiency Brillouin fiber ring laser is demonstrated using the standard single-mode fiber. The laser exhibits a 3.6-mW threshold. The output power is 22 mW with 40-mW pump power, and the maximum optical-to-optical efficiency is 5570. The output is single wavelength with a 3-dB linewidth of 5 MHz, and the interval of center frequency between the laser and the pump light is 11 GHz （0.088 nm）. It is shown that the stimulated Brillouin scattering threshold of ring resonator is lower and the energy transfer efficiency is higher than those in fiber.     

Period-doubling of vector solitons in a ring fiber laser

Period-doubling of vector solitons in a ring fiber laser was experimentally observed for the first time. Apart from period-doubling of single vector soliton, period-doubling of multiple vector solitons was observed as well. Numerical simulation verified the experimental observation.     

双端泵浦保偏光纤激光器

以两台808 nm半导体激光器LD1和LD2为泵浦源,对光纤激光器双端泵浦进行了研究,获得了6.5 W的激光输出。实验分别测出了LD1和LD2半导体激光器单端泵浦和双端泵浦时的输出功率,对双端泵浦输出功率与单端泵浦功率之和进行了比较,利用双端泵浦提高了泵浦效率和输出激光功率。同时测量了输出激光的偏振度,通过计算得到双端泵浦输出激光的偏振度为0.5。     

双端泵浦保偏光纤激光器

 以两台808 nm半导体激光器LD1和LD2为泵浦源,对光纤激光器双端泵浦进行了研究,获得了6.5 W的激光输出。实验分别测出了LD1和LD2半导体激光器单端泵浦和双端泵浦时的输出功率,对双端泵浦输出功率与单端泵浦功率之和进行了比较,利用双端泵浦提高了泵浦效率和输出激光功率。同时测量了输出激光的偏振度,通过计算得到双端泵浦输出激光的偏振度为0.5。     

Generation of domain-wall solitons in an anomalous dispersion fiber ring laser

We report experimental observations performed using a net anomalous dispersion Er-doped fiber ring laser without polarization-selective elements, highlighting the domain-wall solitary pulses generated under the incoherent polarization coupling. By adjusting the pump power and the polarization state appropriately, bright and dark solitons can stably co-exist in the cavity, both centered at 1562.16 nm with a 3-dB spectral width of ～ 0.15 nm and a repetition rate of 3.83 MHz. Moreover, the 0.8 mm long thulium-doped fiber (TDF) facilitated the mode-locking and self-starting of the laser. This is the first demonstration of a laser being used to generate bright and dark solitons synchronously while using TDF as the saturable absorber (SA). Except possessing the all-fiber structure, the laser exhibits good stability, which may have a significant influence on improvement of the pulse-laser design, and may broaden practical applications in optical sensing, optical communication, and soliton multiplexed systems.     

Controllable optical delay line using a Brillouin optical fiber ring laser

A controllable optical delay line using a Brillouin optical fiber ring laser is demonstrated and a large timedelay is obtained by cascading two optical fiber segments. In experiment, a single-mode Brillouin opticalfiber ring laser is used to provide Stokes wave as probe wave. We achieve a maximum tunable time delayof 61 ns using two cascading optical fiber segments, about 1.5 times of the input probe pulse width of 40ns. In the meantime, a considerable pulse broadening is observed, which agrees well with the theoreticalprediction based on linear theory.     

Energy quantization of twin-pulse solitons in a passively mode-locked fiber ring laser

A novel twin-pulse form of solitary wave was recently revealed in a passively mode-locked fiber ring laser. In this paper we report on the energy quantization feature of the twin-pulse solitons in the laser. We show that, as in the case of single-pulse solitons, multiple twin-pulse solitons can coexist in the laser cavity, and, in particular, that all of them have exactly the same pulse energy and twin-pulse separation. The pump-power hysteresis effect previously reported for the single-pulse soliton operation is also observed for the twin-pulse soliton operation of the laser. PACS 42.81.Dp; 42.55.Wd; 42.60.Fc     

All-optical dynamic grating generation based on Brillouin scattering in polarization-maintaining fiber

We report a novel kind of all-optical dynamic grating based on Brillouin scattering in a polarization maintaining fiber (PMF). A moving acoustic grating is generated by stimulated Brillouin scattering between writing beams in one polarization and used to reflect an orthogonally polarized reading beam at different wavelengths. The center wavelength of the grating is controllable by detuning the writing beams, and the 3 dB bandwidth of approximately 80 MHz is observed with the tunable reflectance of up to 4% in a 30 m PMF.     

Tunable microwave generation based on a Brillouin fiber ring laser and reflected pump

A simple approach for photonic generation of a tunable microwave signal is proposed and successfully demonstrated. By mixing the output from a single-longitudinal-mode Brillouin fiber ring laser with the reflected laser pump at photodetector, a microwave signal at the Brillouin shift can be obtained. Since the Brillouin shift can be changed by tuning the pump wavelength, tunable microwave can be generated. As a result a microwave signal tunable from 10.39 to 10.67 GHz has been achieved, with linewidth less than 600 KHz.     

Passive harmonic mode locking of twin-pulse solitons in an erbium-doped fiber ring laser

We report on the experimental observation of passive harmonic mode locking of twin-pulse solitons in an erbium-doped fiber ring laser. Experimental investigations on the passive harmonic mode locking of both the single-pulse and the twin-pulse solitons revealed that, apart from the gain recovery and acoustically induced soliton interactions, the global soliton interaction mediated through an unstable CW lasing in the laser cavity also plays an important role in the formation of the state in the laser.     

Switchable single-longitudinal-mode dual-wavelength erbium-doped fiber ring laser based on one polarization-maintaining fiber Bragg grating incorporating saturable absorber and feedback fiber loop

Switchable single-longitudinal-mode (SLM) dual-wavelength erbium-doped fiber ring laser based on one polarization-maintaining fiber Bragg grating (PMFBG) is demonstrated. Due to the enhancement of the polarization hole burning (PHB) by the PMFBG, the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting a polarization controller (PC). The stable SLM operation is guaranteed by a compound-ring cavity and a saturable absorber (SA). The optical signal-to-noise ratio (OSNR) is over 45 dB. The amplitude variation in nearly one and half an hour is less than 0.2 dB.     

L-band polarization-controlled multiple dissipative solitons generation in a normal dispersion fiber ring laser

A polarization-controlled multiple dissipative solitons generation in a normal dispersion fiber ring laser operating in L-band is demonstrated. The fiber laser is passively mode-locked with nonlinear polarization rotation (NPR) technique. Depending on the rotations of the PCs, the number of the pulses circulating in the laser cavity can be tuned from 1 to 4. The experimental results suggest that the generation of multiple pulses is caused by the soliton shaping of dispersive waves induced by the variations of spectral filtering effect.     

Single-frequency Brillouin distributed feedback fiber laser

We demonstrate a single-frequency Brillouin distributed feedback laser (DFB). The DFB laser cavity was a 12.4 cm long fiber Bragg grating with a π-phase shift offset from the grating center. It exhibited a threshold of 30 mW and conversion efficiency from pump to Stokes wave as high as 27%. Higher-order Stokes waves were suppressed by more than 20 dB. The Stokes output of the laser could be obtained in either the forward or backward direction, simply by changing the orientation of the offset of the discrete phase shift with respect to the pump propagation direction. The DFB laser operated over a pump frequency range of 1.2 GHz, more than 60 times larger than the SBS gain bandwidth.     

基于偏振保持掺Er3+光纤的高稳定性单波长光纤激光器

研制出光敏偏振保持掺Er³⁺光纤,通过在这种光纤上紫外写入三个光纤光栅,形成对抽运激光高转化效率的谐振腔.在输出功率为23.617dBm、工作波长为976nm的激光抽运下,得到均值功率为9.20dBm、均值中心波长为1554.554nm的单波长激光输出.在室温下800min（约13.3h）的测量时间内,其输出功率的波动为±0.05dB,中心工作波长的波动为±0.0015nm. 关键词： 光纤激光器 3+光纤')" href="#">偏振保持掺Er³⁺光纤 光纤Bragg光栅     

Switchable triple-wavelength erbium-doped fiber laser using a single fiber Bragg grating in polarization-maintaining fiber

A stable and narrow wavelength spacing multiwavelength erbium-doped fiber laser is proposed and demonstrated. The laser can produce simultaneous dual- and triple-wavelength lasing oscillations with a narrow wavelength spacing of less than 0.1 nm via using a single fiber Bragg gratings written in polarization-maintaining (PM) fiber. By adjusting polarization controller, the wavelength spacing of dual-wavelength lasing oscillations can be tuned to as small as 0.032 nm. The maximum amplitude variation for every lasing wavelength is less than 0.5 dB. The room-temperature operation principle is based on the polarization hole burning and deeply saturated effect in an ordinary erbium-doped fiber ring laser (EDFRL). The laser has the advantages of simple all-fiber configuration, low cost, high stability and operating at room temperature.     

低阈值锁模状态可转换的全保偏光纤激光器

报道了一种可实现低阈值自启动的全保偏九字腔光纤激光器.谐振腔结构中使用相移器降低锁模阈值,当泵浦功率达到120 mW时,便可实现自启动的传统孤子锁模,中心波长为1530 nm,脉冲宽度为614.6 fs.随后泵浦功率逐渐增大到470 mW,实现了从孤子脉冲到类噪声脉冲的转换,在该锁模状态下的激光器输出功率为63.2 m...