Multiwavelength Fiber Ring Laser Research Articles

Theory and experiment of a fiber loop mirror filter of two-stage polarization-maintaining fibers and polarization controllers for multiwavelength fiber ring laser

A fiber loop mirror (FLM) filter with two-stage polarization-maintaining fibers (PMFs) and polarization controllers (PCs) is presented. The transmission function of this FLM is calculated in detail by Jones matrix. The wavelength interval depends on both the PMFs and the PCs. The side frequencies can be restrained by choosing appropriate length of the PMFs. Furthermore, an erbium-doped fiber ring laser based on this FLM filter is proposed and demonstrated. Stable single-, double- and triple-wavelength are achieved respectively. The 3 dB line-width is less than 0.03 nm, and the fluctuation of wavelength and peak power is less than 0.05 nm and 0.1 dB in 30 minutes.

Switchable Multi-Wavelength Erbium-Doped Fiber Lasers Based on a Mach–Zehnder Interferometer Using a Twin-Core Fiber

A switchable multi-wavelength erbium-doped fiber ring laser based on a compact in-fiber Mach–Zehnder interferometer comb filter at room temperature is presented. The comb filter is formed by splicing a section of twin-core fiber between two single mode fibers. By adjusting the states of the polarization controller appropriately, the laser can be made to operate in stable single-, dual- and three-wavelength lasing states. The operation principle is based on spectral hole burning induced by the saturated effect and polarization hole burning.

Multi-wavelength erbium-doped fiber ring laser based on wavelength-dependent polarization rotation with a phase modulator and an in-line comb filter

A stable room-temperature multi-wavelength erbium-doped fiber ring laser has been proposed and investigated experimentally. A phase modulator composed of a piece of fiber wrapped around a cylindrical piezoelectric transducer is used to suppress the mode competition. And the combined action between optical fiber and polarization-dependent isolator provides the wavelength-dependent loss induced by wavelength-dependent polarization rotation mechanism to flatten the output spectrum, tune the locations and improve the number of the lasing lines. Stable multi-wavelength lasing with wavelengths up to 23 and the wavelength spacing of 0.4 nm is demonstrated. Moreover, the pulse train output was also observed.

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.

Multiwavelength fiber ring laser based on a semiconductor and fiber gain medium

We report a novel multi-wavelength laser source based on hybrid gain medium, with a semiconductor optical amplifier and erbium doped fiber amplifier, and a double-ring structure. More than 60 lines with more than 50 dB signal-to-noise ratio (SNR) have been achieved in our setup. The wavelength interval between the wavelengths is approximately 0.32 nm. The 3 dB spectral width of each lasing line is approximately 0.019 nm. The laser can be tuned from approximately 1526 nm to approximately 1562 nm by adjusting the loss in the cavity.

Stable multiwavelength fiber ring laser with equalized power spectrum based on a semiconductor optical amplifier

We experimentally demonstrated a new structure of a multiwavelength semiconductor optical amplifier (SOA) ring laser based on a fiber Sagnac loop filter that can generate up to 25 stable output lasing wavelengths at room temperature. By varying the length of a polarization-maintaining (PM) fiber within the Sagnac loop filter, the wavelength spacing between the output lasing wavelengths can be changed to a desired value. By tuning a polarization controller (PC) within the Sagnac loop filter, stable multiwavelength 1550-nm operation with up to 17 lasing lines within 3 dB power level variation and with a wavelength spacing of ∼0.8 nm was achieved. The optical signal-to-noise ratios (OSNRs) of all the lasing wavelengths are greater than 40 dB.

基于啁啾莫尔光栅和半导体光放大器的多波长光纤激光器

A simple and cost-effective multi-wavelength fiber ring laser based on a chirped Moire fiber grating (CMFG) and a semiconductor optical amplifier (SOA) is proposed. Stable triple-wavelength lasing oscillations at room temperature are experimentally demonstrated. The measured optical signal-to-noise ratio (SNR) reaches the highest value of 50 dB and the power fluctuation of each wavelength is less than 0.2 dB within a 1-h period. To serve as a wavelength selective element, the CMFG possesses excellent comb-like filtering characteristics including stable wavelength interval and ultra-narrow passband, and its fabrication method is easy and flexible. The lasing oscillation shows a narrower bandwidth than SOA-based multi-wavelength fiber lasers utilizing some other kinds of wavelength selective components. Methods to optimize the laser performance are also discussed.

基于半导体光放大器和取样光纤光栅结合Sagnac环的多波长光纤激光器

基于半导体光放大器和取样光纤光栅结合Sagnac环的多波长光纤激光器

Voltage-tuned multiwavelength Raman ring laser with high tunability based on a single fiber Bragg grating

A practical scheme for a tunable multiwavelength Raman fiber ring laser based on a single fiber Bragg grating with a voltage-controllable coil heater is investigated. The number of phase-shifted regions within a single fiber grating determines the number of reflection peaks and the number of lasing wavelengths in the multiwavelength Raman fiber ring laser. A stable multiwavelength Raman fiber ring laser with low output peak-power fluctuation of less than 0.5 dB at room temperature is achieved. A multiwavelength Raman fiber ring laser with a high extinction ratio of more than 50 dB is realized. High flatness is obtained for three lasing peaks, and the lasing peak-power difference is measured to be less than 0.2 dB. A voltage-controllable coil heater with heating elements is used to effectively control three lasing wavelengths in the multiwavelength output, and the tunability of each lasing wavelength is measured to be 0.11 nm/V.

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.

Numerical analysis of multiwavelength erbium-doped fiber ring laser exploiting four-wave mixing

In this paper, a model is proposed to study the behavior of four-wave mixing assisted multiwavelength erbium doped fiber ring laser based on the theoretical model of the multiple FWM processes and Gile's theory of erbium-doped fiber. It is demonstrated that the mode competition can be effectively suppressed through FWM. The effect of phase matching, the nonlinear coefficient, the power in the cavity and the length of the nonlinear medium on output spectrum uniformity are also investigated.

Medium-power erbium-ytterbium-codoped multiwavelength fiber laser

This paper describes the design and operation of a stable single-longitudinal-mode medium-power multiwavelength fiber ring laser at room temperature. Single-longitudinal-mode oscillation was achieved by using an unpumped polarization-maintaining erbium-doped fiber inside the cavity as a saturable absorber. To investigate the function of the saturable absorber, erbium-doped fibers with different erbium concentrations and lengths were used. The output characteristics of the laser were studied using a scanning Fabry-Perot spectrum analyzer of resolution 27 MHz and an optical spectrum analyzer of resolution 6.25 GHz. The total output power of the laser obtained was more than 100 mW. The minimum separation between lasing wavelengths for stable single-longitudinal-mode oscillations, number of lasing lines, tunability, and maximum available output power were also explored.

Lyot filter based multiwavelength fiber ring laser actively mode-locked at 10 GHz using an electroabsorption modulator

A multiwavelength fiber ring laser comprising of a Lyot filter and hybrid gain medium is presented. A wavelength channel spacing of 100 GHz is achieved by appropriate tuning of the Lyot filter length. Four wavelength channels are simultaneously mode-locked at 10 GHz using an electroabsorption modulator. We highlight how the intra-cavity modulator can affect the stability of the mode-locked laser spectrum when used in conjunction with a Lyot filter. We show that, due its reduced polarization sensitivity, an electroabsorption modulator significantly improves the stability of the mode-locked laser spectrum when compared to using a Mach–Zehnder modulator.

Tunable multiwavelength fiber laser using a comb filter based on erbium-ytterbium co-doped polarization maintaining fiber loop mirror

A tunable comb filter based on a fiber loop mirror setup, which incorporates a piece of pumped erbium-ytterbium co-doped polarization maintaining fiber, is newly presented. It is accomplished by controlling the pump power or adjusting a polarization controller in the loop mirror, which results from the fact that the effective birefringence of the erbium-ytterbium co-doped polarization maintaining fiber depends on the pump power and polarization state of the traversing signal. By using the proposed comb filter, a continuously tunable multiwavelength fiber ring laser in the L-band is successfully demonstrated.

Multiwavelength Mode-Locked Fiber-Ring Laser Based on Reflective Semiconductor Optical Amplifiers

An active multiwavelength mode-locked fiber ring laser is demonstrated by exploiting cross-gain modulation in a reflective semiconductor optical amplifier. A length of dispersion-compensation fiber is incorporated in the ring cavity to enhance the multiwavelength performance. Simultaneous tunable triple-wavelength mode-locking is implemented with the pulse repetition of 10 GHz and wavelength spacing of 1.12 nm. The results provide an effective approach to fulfill all-optical clock recovery and data pattern conversion in multiwavelength for future optical communication systems.

Novel Multiwavelength Erbium-Doped Fiber and Raman Fiber Ring Lasers With Continuous Wavelength Spacing Tunability at Room Temperature

In this paper, we investigate a flexibly tunable multiwavelength fiber ring laser with a continuous wavelength spacing tunability, incorporating a superimposed chirped fiber Bragg grating (CFBG) at room temperature. We exploit versatile gain media such as erbium-doped fiber (EDF) and Raman amplifiers in generating the multiwavelength fiber ring laser. The wavelength spacing of a superimposed CFBG can be continuously controlled by modifying the chirp ratio of the grating with the specially designed apparatus. After configuring a fiber ring cavity with the proposed multichannel filter, we realize stable multiwavelength fiber ring lasers at room temperature, which are based on an EDF amplifier incorporating a highly nonlinear dispersion-shifted fiber or a Raman amplifier using a dispersion-compensated fiber. Power fluctuation is less than ~0.6 dB. No lasing wavelength change is severally observed for the whole tuning range. For the multiwavelength EDF laser, stable 11-wavelength simultaneous operation spaced at 0.51 nm, with a signal-to-noise ratio (SNR) of more than ~45 dB at room temperature, is achieved. A high-quality multiwavelength Raman laser output with stable 30 lasing wavelengths spaced at 0.51 nm with a high SNR of more than ~45 dB is also realized. By applying the proposed tuning technique to both the multiwavelength EDF and Raman lasers, a wide and continuous tunability of lasing wavelength spacing is successfully achieved, which is measured to be ~ plusmn0.033 nm/mm. By controlling the pump power in the multiwavelength Raman fiber ring laser, we can control the number of lasing channels at a wavelength spacing of 0.51 nm.

Multiwavelength Raman fiber laser inserting a sampled chirped fiber Bragg grating

AbstractA simple multiwavelength Raman fiber ring laser with equalized peak power is proposed and demonstrated experimentally by inserting a sample chirped fiber Bragg grating. By adjusting the polarization controller (PC) in the ring cavity, up to ten stable wavelengths with equalized peak power are achieved at room temperature. The Raman fiber ring laser has many advantages such as simple structure, low loss, and multiwavelength lines with moderate output power. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2242–2245, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22652

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.

Room-temperature multiwavelength erbium-doped fiber ring laser based on phase modulation of semiconductor optical amplifier with lasing-wavelength and spacing tunability

We have experimentally investigated a stably tunable multiwavelength erbium-doped fiber ring laser based on phase modulation of a semiconductor optical amplifier with lasing wavelength and spacing tunability at room temperature. Stable multiwavelength operation is obtained by direct modulation of the bias current in the amplifier. We demonstrate such a laser incorporating a tunable Lyot-Sagnac filter with two segments of polarization-maintaining fibers with wavelength-spacing and lasing wavelength tunability. We successfully achieved 1.0-nm-spacing eight-channel and 0.8-nm-spacing ten-channel lasing wavelengths at room temperature. The lasing wavelength of the laser can be also controlled by a polarization controller.

Stable multiwavelength erbium-doped fiber ring laser using self-lasing feedback

An effective approach to enhance the performance of a room-temperature multiwavelength fiber ring laser is presented. By introducing self-lasing feedback in conventional phase-modulation-based multiwavelength fiber ring lasers, the number of lasing lines is increased and the differences among the lasing lines are diminished. Stable multiwavelength lasing with numbers of lasing lines up to 17 within the 3-dB spectral bandwidth and with wavelength spacing as small as 0.2 nm is achieved.