Waveband switchable multi-wavelength erbium-doped fiber ring laser based on wavelength-dependent polarization rotation mechanism

A waveband switchable multi-wavelength erbium-doped fiber ring laser based on wavelength-dependent polarization rotation mechanism and birefringence-based in-line comb filter is proposed and demonstrated. The two lasing wavebands, around 1530 and 1560 nm region, can be efficiently switched by simply rotating the polarization controllers (PCs). The channel spacing is 0.4 nm which was determined by the length of polarization maintain fiber (PMF) used in the experiment. The experimental results show that the waveband switchable is an intrinsic feature of multi-wavelength fiber ring lasers by incorporating a passive polarizer in the laser cavity.     

Switchable multi-wavelength erbium-doped fiber laser based on a four-mode FBG

We propose a switchable multi-wavelength erbium-doped fiber laser based on a four-mode fiber Bragg grating(FBG). The four-mode FBG is fabricated in a hydrogen pre-loaded fiber by the phase mask method, which can support four linearly polarized modes around 1550 nm. The five operation wavelengths are at 1547.5, 1546.8,1546.0, 1545.1, and 1544.2 nm, respectively. Through adjusting the polarization state and the lateral offset coupling in cavity, the laser can be switched into the operation state of single, dual, or triple wavelengths. The proposed laser has the advantages of simple configuration, stable operation, and easy adjustment.     

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 multi-wavelength erbium-doped fiber ring laser based on cascaded polarization maintaining fiber Bragg gratings in a Sagnac loop interferometer

A switchable multi-wavelength erbium-doped fiber (EDF) ring laser based on cascaded polarization maintaining fiber Bragg gratings (PMFBGs) in a Sagnac loop interferometer as the wavelength-selective filter at room temperature is proposed. Due to the polarization hole burning (PHB) enhanced by the PMFBGs, stable single-, dual-, three- and four-wavelength lasing operations can be obtained. The laser can be switched among the stable single-, dual-, three- and four-wavelength lasing operations by adjusting the polarization controllers (PCs). The optical signal-to-noise ratio (OSNR) is over 50 dB.     

Tunable multi-wavelength fiber ring laser based on a Hi-Bi fiber loop mirror

A novel tunable multi-wavelength fiber ring laser based on semiconductor optical amplifier(SOA)is proposed by using a high-birefringence(Hi-Bi)fiber loop mirror(FLM)as wavelength filter.With this configuration,the wavelength spacing of this laser can be varied by using the different lengths of Hi-Bi fiber.8 wavelengths spacing on 450 GHz are experimentally obtained with more than 25-dB signal-to-noise ratio(SNR)for each channel using 1.28-m Hi-Bi fiber in Hi-Bi FLM.The output power variation between different channels is measured to be less than 5.9 dB.The linewidth of each channel is compressed from 0.347 to 0.186 nm by 1.5-m unpumped erbium-doped fiber(EDF).Meanwhile,17 wavelengths spacing on ITU-gird(100 GHz)are also obtained with 5.9-m Hi-Bi fiber in Hi-Bi FLM.All these channels can be tuned together over 0.4 nm.     

Stable multi-wavelength erbium-doped fiber laser based on dispersion-shifted fiber and Sagnac loop filter

A multi-wavelength erbium-doped fiber laser (MEDFL) with simple line structure is experimentally demonstrated by using a Sagnac interferometer as a comb filter. It is shown that the multi-wavelength lasing is quite stable at room temperature due to the four-wave mixing (FWM) effect among different laser channels in the dispersion-shifted fiber cooperated in the laser cavity.     

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.     

FWM-based multi-wavelength erbium-doped fiber laser using Bi-EDF

We experimentally demonstrate a simple structure but efficient multi-wavelength erbium-doped fiber laser (EDFL) using a 49 cm Bismuth-based erbium-doped fiber (Bi-EDF) as gain medium. The Bi-EDF provides erbium amplification and FWM effect in the cavity to generate a stable multi-wavelength comb operating in C-band region. We have achieved more than 5 lines with peak power of more than −35 dBm and channel spacing of 0.5 nm by incorporating a broadband fiber Bragg grating and polarization controller in the ring cavity.     

Tunable dual-wavelength fiber laser based on a polarization-maintaining fiber Bragg grating and a Hi-Bi fiber optical loop mirror

We demonstrate experimentally the operation of a linear cavity dual-wavelength fiber laser using a polarization maintaining fiber Bragg grating (PM-FBG) as an end mirror that defines two closely spaced laser emission lines. The PM-FBG is also used to tune the laser wavelengths. The total tuning range is ∼8 nm. The laser operates in a stable dual-wavelength mode for an appropriate adjustment of the cavity losses for the generated wavelengths. The high birefringence (Hi-Bi) fiber optical loop mirror (FOLM) is used as a tunable spectral filter to adjust the losses. The FOLM adjustment was performed by the temperature control of the Hi-Bi fiber.     

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.     

Dual-cavity dual-output multi-wavelength fiber laser based on nonlinear polarization rotation effect

We demonstrate a multi-wavelength fiber laser based on nonlinear polarization rotation (NPR) in dual-cavity configuration with two output ports. The laser employs a piece of erbium doped fiber (EDF) and semiconductor optical amplifier (SOA) as the gain medium in a separate cavity. By incorporating PCF in the dual cavity the non-linear polarization rotation (NPR) effect is enhanced and thus higher output and more oscillating lasing can be achieved. The laser produces three strong lines with a spacing of 2.40 nm and side mode suppression ratio (SMSR) of more than 10 dB at 1535 nm region. Another output produces 8 lines of optical comb with a spacing of 0.54 at 1570 nm region.     

A novel double-Brillouin-frequency spaced multi-wavelength Brillouin erbium-doped fiber laser based on non-linear amplified fiber loop mirror

In the paper, a ring double-Brillouin-frequency spaced multi-wavelength Brillouin erbium-doped fiber laser based on non-linear amplified fiber loop mirror filter is demonstrated, in which the non-linear amplified fiber loop mirror (AFLMF) is used as a filter. At the 980 nm pump power of 10.29 dBm, the tunable laser source center wavelength of 1563 nm and power of −3 dBm, up to 12 even output channels with 0.16 nm spacing are achieved. At the same time, we study the influence of 980 nm pump power, the polarization controller and the tunable laser source center wavelength on the number of Stokes light wave.     

Tunable single- and dual-wavelength erbium-doped fiber laser based on Sagnac filter with a high-birefringence photonic crystal fiber

In this paper, we observed and experimentally investigated a high-performance single- and dual-wavelength erbium-doped fiber ring laser based on a Sagnac filter which contains a section of high-birefringence photonic crystal fiber (HB-PCF) and a polarization controller. Incorporation of the high-birefringence photonic crystal fiber can suppress multimode oscillation, improve power stability and increase the optical signal-to-noise ratio (SNR). Wavelength tunable was achieved by using a polarization controller in the Sagnac filter. Highly stable single-, dual-wavelength oscillations are tunable within a wavelength range from 1550 to 1562 nm and SNR as high as 57 dB with narrow line width about 0.011 nm, is experimentally demonstrated.     

Tunable multiwavelength erbium-doped fiber laser based on intensity-dependent loss and intra-cavity loss modulation

A tunable multiwavelength erbium-doped fiber laser is proposed and experimentally studied. The intensity-dependent loss (IDL) in a nonlinear optical loop mirror is utilized for stable multiwavelength lasing output. The accurate switch operation, i.e., the lasing lines emerge/disappear one by one at the longer wavelength side of the initial one, is achieved by adjusting the intra-cavity loss using a variable attenuator. The effect of the intra-cavity loss on the lasing characteristics is theoretically analyzed. Numerical results confirm the experiment measurements and suggest that both the IDL and the gain spectrum, which vary with the intra-cavity loss, lead to the observed tunable lasing behavior.     

Incorporate, switchable dual-wavelength fiber laser with Bragg gratings written in a polarization-maintaining erbium-doped fiber

A stable, incorporate and switchable dual-wavelength fiber laser with two fiber Bragg gratings written in a photosensitive and polarization-maintaining erbium-doped fiber directly, that is, without splices in the laser cavity, is proposed and demonstrated. Simultaneous dual-wavelength oscillation is achieved at room temperature with a wavelength spacing of 0.343 nm. The power fluctuation and wavelength shift of single-wavelength oscillations are measured to be less than 0.24 dB and 0.013 nm over 2 h. The wavelength switchability between single- and dual-wavelength oscillations is realized by altering the voltage upon the electrostrictive ceramic actuator.     

Multiwavelength erbium-doped fiber laser based on nonlinear polarization rotation assisted by four-wave-mixing

We experimentally demonstrate a simple-structure but efficient multiwavelength erbium-doped fiber laser based on nonlinear polarization rotation assisted by four-wave-mixing (FWM). Based on the combination of these two nonlinear mechanisms contributing to intensity-dependent loss to alleviate mode competition, the stable multiwavelength operation at room temperature can be realized in a length of dispersion-shifted fiber. We achieved up to 38-wavelength generation with a spacing of ∼0.4 nm in the laser. In addition, through tuning the birefringence fiber filter, the lasing wavelength can be accurately tuned in the free spectrum range.     

Discrimination of strain and temperature based on a polarization-maintaining photonic crystal fiber incorporating an erbium-doped fiber

A simple sensing method for simultaneous measurement of temperature and strain is investigated by using a Sagnac fiber loop mirror composed of a polarization-maintaining photonic crystal fiber (PM-PCF) incorporating an erbium-doped fiber (EDF). Amplified spontaneous emission created by a pumped EDF is transmitted to a Sagnac fiber loop mirror. The interference between two counter-propagating signals in a Sagnac fiber loop mirror generates a periodic transmission spectrum with respect to wavelength. When external temperature is increased, the transmission peak power reduces because the amplified spontaneous emission of the EDF is decreased by the applied temperature change (0.04 dB/°C). The peak wavelength is shifted into the shorter wavelength because of the negative temperature dependence of the birefringence of the PM-PCF (0.3 pm/°C). As the applied strain increases, the peak wavelength of the transmission spectrum of the Sagnac loop mirror incorporating the EDF shifts into a longer wavelength (1.3 pm/με) because the phase change of the proposed sensing probe is directly proportional to the applied strain. The transmission peak power, however, is not changed by the applied strain. Since the source and the sensing probe are integrated, the overall system configuration is significantly simplified without requiring any additional broadband light source. Therefore, it is possible to simultaneously measure temperature and strain by monitoring the variation of transmission peak power and peak wavelength, respectively.     

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.     

Distributed strain sensor based on dynamic grating in polarization-maintaining erbium-doped fiber

A novel distributed fiber-optic strain sensor based on dynamic grating in polarization-maintaining erbium-doped fiber (PM-EDF) is demonstrated experimentally. The dynamic grating is written with light beams polarized along one primary polarization axis of the PM-EDF, and read with a light beam polarized along the other primary polarization axis. When a strain is applied to the fiber, the detected Bragg reflection frequency of the dynamic grating shifts in proportion to the birefringence change, which is proportional to the strain. By employing the technique of synthesis of optical coherence function, the dynamic grating is localized in a region that can be shifted to sweep along the fiber to determine the location of the strain. In the experiment, a spatial resolution of 20 cm is demonstrated.