Stable Multiwavelength Fiber Laser Research Articles

Generation of multiwavelength bismuth-doped fiber laser based on all-fiber Lyot filter

A stable multiwavelength fiber laser was proposed and demonstrated using a bismuth-doped fiber together with an all-fiber Lyot filter. The proposed multiwavelength bismuth-doped fiber laser (BDFL) spectrum can generate up to 21 output channels between 1309.88 nm and 1313.69 nm by carefully adjusting two polarization controllers (PCs). The multiwavelength BDFL shows good stability over time with a signal-to-noise ratio (SNR) of 48.69 dB, contributing to the average power fluctuations of 0.6 dB and wavelength drift of less than 0.1 nm in the laser output. In addition, the multiwavelength BDFL exhibits a free spectral range (FSR) of about 0.192 nm and a frequency bandwidth of 33.45 GHz. The characteristics of the multiwavelength BDFL can be observed by varying the pump power of the pump source, lasing output at different lengths of polarization maintaining fiber (PMF), and the generation in multiwavelengths using additional single mode-fiber (SMF).

Highly stable multi-wavelength fiber laser based on hybrid enclosed two-armed fiber filter

A compact multi-wavelength fiber laser (MWFL) with high stability based on hybrid enclosed two-armed fiber filter (HETAFF) is demonstrated. The HETAFF composes of an enclosed Mach-Zehnder interferometer with an in-line polarization controller (PC) in one arm of optical couplers #1 (OC1) and a section of polarization maintaining fiber with two PCs in OC2 loop. By using the HETAFF in proposed fiber laser, a lasing state switchable and wavelength-interval adjustable MWFL is obtained. It can be switched in single-, dual-, triple-, quadruple- and quintuple-wavelength states. The wavelength-interval can be adjusted as it operates in dual-, triple- and quadruple-wavelength states. Its optical signal to noise ratio (OSNR) is more than 36.03 dB, and the lasing wavelength shift and power fluctuation are less than 0.08 nm and 0.94 dB, respectively. The output characteristics, such as abundant laser states and high stability, are inseparable from the unique performance of the HETAFF.

Q-switching near-infrared multiwavelength generation by intracavity tungsten-oxide-induced four-wave mixing in an erbium-doped fiber laser.

We report on the generation of a stable multiwavelength Q-switched erbium-doped fiber laser based on tungsten oxide nanoparticles (WO3 NPs) combined with an intracavity comb filter for the first time, to the best of our knowledge. The prepared WO3-PVA thin film has a modulation depth and saturable intensity of 20% and 100 MW/cm2, respectively. A spectrum of up to 15 peaks with a channel spacing of 0.48nm has been obtained. In the Q-switching regime, a minimum pulse width of 4.24μs and a maximum repetition rate of 52.49kHz were achieved at a maximum pump power of 300mW. The dual effect of WO3 NPs in saturable absorption and high optical nonlinearity has induced pulsed and four-wave mixing effects. Therefore, the intrinsic advantages of WO3 nanomaterial provide a promising source for the realization of a stable multiwavelength fiber laser.

Switchable, tunable and highly stable multi-wavelength fiber laser based on a spectral filter

In this work, a switchable and tunable multi-wavelength erbium-doped fiber laser based on a spectral filter is presented. Here, the filter is formed by polymer and silicon layers at the tip of an optical fiber. The laser emission wavelengths are mainly determined by the position where the most intense fringes of the reflectivity spectrum of the filter occurs. Moreover, the number of laser emissions are controlled and switched by using a variable optical attenuator inserted into the laser cavity. In this way, single-, dual-, triple-, and quadruple-laser emissions can be obtained within the long operating span from ~1526–~1565 nm. Additionally, the multi-wavelength laser emissions had a side mode suppression ratio ⩾36.48 dBm, a minimum wavelength spacing of ~3.6 nm, and the best peak power difference was 0.45 dB. Besides, the wavelength shift and peak power fluctuation were ⩽0.095 nm and ⩽3.14 dB, respectively, over half an hour. Finally, the emissions of the multi-wavelength laser can be tuned within a tunable range of 2.93 nm by taking advantage of some thermal properties of the Si and polymer layers.

Fabrication and Characterization of 2 × 2 Microfiber Coupler for Generating Two Output Stable Multiwavelength Fiber Lasers

A compact 2 × 2 microfiber coupler (MC) is proposed and experimentally demonstrated for the generation of stable multiwavelength fiber laser in the C-band region. The 2 × 2 MC is fabricated by twisting and fusing together two lateral dual single mode fibers using the flame-brushing technique. The 2 × 2 MC has a waist diameter of 8 μ m with a coupling ratio of 38:62 and 45:55 at ports 1 and 2, respectively. The 2 × 2 MC exploits super mode coupling to produce spatial mode beating and suppress mode competition of the homogeneous gain medium in a fiber ring laser. The channel spacing of the output wavelengths is immune to changes in the external environment and can be extracted from the peaks of the 2 × 2 MC's periodic oscillation. The proposed laser is capable of generating stable single, dual, and triple lasing wavelengths from its two output ports over a range of more than 29 nm, which is further enhanced by the polarization rotation mechanism. The generating lasing wavelengths have a 3 dB line-width of less than ∼30 pm and peak-to-floor ration of about 58 dB at a pump power of 38 mW.

Stable multi-wavelength fiber lasers for temperature measurements using an optical loop mirror.

In this work, two novel stable multi-wavelength fiber laser configurations are proposed and demonstrated by using a spool of a single-mode fiber as an optical loop mirror and one or two fiber ring cavities, respectively. The lasers are comprised of fiber Bragg grating reflectors as the oscillation wavelength selecting filters. The influence of the length of the spool of fiber on the laser stability both in terms of wavelength and laser output power was investigated. An application for temperature measurement is also shown.

Stable multi-wavelength fiber laser with single-mode fiber in a Sagnac loop.

In this paper, we propose and experimentally demonstrate a stable multi-wavelength fiber laser at 1.5 μm with single-mode fiber (SMF). The Sagnac loop structure with a 48.6:51.4 coupler and 2 km SMF has an intensity-dependent loss, which contributes to suppress the mode competition in the cavity and leads to a steady multi-wavelength output. In the experiment, five stable lasing wavelengths are obtained with a pump power of 300 mW at 980 nm. The demonstrated multi-wavelength fiber laser has great potential for applications in optical communications and optical sensing systems.

Stable multi-wavelength fiber laser based on a compounded nonlinear polarization rotation effect

A stable multi-wavelength polarization-maintaining erbium-doped fiber (PM-EDF) laser with high signal-to-noise ratio (SNR) based on a compounded nonlinear polarization rotation effect (CNPRE) is proposed and demonstrated. In order to effectively reduce homogeneous broadening of EDF and then to the alleviate mode competition, two sandwich configurations formed by a polarization dependent isolator (PDI) or a segment of single-mode fiber sandwiched between two polarization controllers (PC), are introduced into the ring cavity to generate the CNPRE. A home-made asymmetry twin-core fiber (ATCF) is also incorporated in the ring cavity as a comb filter. With only 150 mW pump power, there are up to 45-wavelengths lasing with the approximate amplitude in a 3 dB bandwidth generated at room temperature. The wavelength spacing between the adjacent peaks is 0.29 nm and the highest SNRs reach 41.5 dB by optimizing the state of polarization of PCs. The power fluctuation and wavelength shift for each lasing wavelength are less than 0.05 dB and 0.02 nm, respectively. This indicates that the proposed multi-wavelength fiber laser can be stably operated at room temperature.

Use of a reflective semiconductor optical amplifier and dual-ring architecture design to produce a stable multi-wavelength fiber laser

In this work, we propose and demonstrate a multi-wavelength laser source produced by utilizing a C-band reflective semiconductor optical amplifier (RSOA) with a dual-ring fiber cavity. Here, the laser cavity consists of an RSOA, a 1 × 2 optical coupler, a 2 × 2 optical coupler and a polarization controller. As a result, thirteen to eighteen wavelengths around the L band could be generated simultaneously when the bias current of the C-band RSOA was driven at 30–70 mA. In addition, the output stabilities of the power and wavelength are also discussed.

Ring resonator for multiwavelength fiber laser using a Sagnac loop filter

A theoretical study of a passive fiber ring resonator with a Sagnac loop filter is reported. It is used to construct a stable multiwavelength fiber laser at room temperatures. The gain medium is an elliptical-core erbium-doped fiber. The principle of operation is based on the polarization-dependent gain phenomena in erbium-doped fiber. The effects of the different parameters of the doped fiber and the loop filter are experimentally studied.