Tunable Multiwavelength Fiber Ring Laser Research Articles

Switchable and tunable multi-wavelength fiber ring laser employing a cascaded fiber filter

• We propose a novel cascaded hybrid fiber filter. • A switchable and tunable multi-wavelength fiber laser. • This laser has excellent robustness because of no core-offset splicing point. • This laser operates more stably compare to the previous similar works. A switchable and tunable multi-wavelength fiber laser based on cascaded hybrid fiber filter (CHFF) is proposed and demonstrated. The CHFF is composed of a single ellipsoid hybrid structure optical fiber filter (SE-HSOFF) and a Sagnac loop interferometer. Here the SE-HSOFF consists of single mode fiber (SMF)-few mode fiber (FMF)-SMF, and there is an ellipsoidal structure fabricated by SMF-FMF. It has the function of realizing the switchability of fiber laser. The Sagnac loop interferometer incorporated with a segment of polarization maintaining fiber (PMF) is used as a tuning component. By adjusting the state of polarization controller (PC), the laser can operate in single-, dual-, triple- and quadruple-wavelength laser states, and the lasing wavelength can be tuned by about 10 nm when it operates in dual-wavelength state. The optical signal to noise ratio (OSNR) is larger than 30.0 dB. This laser has excellent robustness because there is no core-offset splicing point and operates very stably in every output state at room temperature.

Tunable multiwavelength fiber laser based on a θ-shaped microfiber filter

We propose and experimentally demonstrate a flexibly tunable multiwavelength fiber ring laser based on a θ-shaped microfiber filter in conjunction with an erbium-doped fiber amplifier. The stable operation of the multiwavelength lasing is successfully achieved at room temperature, with the peak power fluctuation less than 0.519 dB. By micro-adjusting the cavity length of the filter, the channel spacing can be independently tuned within the gain range of the optical amplifier. We have achieved 0.084 nm-spacing 48 channel, 0.147 nm-spacing 25 channel, 0.190 nm-spacing 20 channel and 0.302 nm-spacing 15 channel lasing wavelengths at room temperature.

Three Channel-Spacing Switchable Multiwavelength Fiber Laser With Two Segments of Polarization-Maintaining Fiber

A three channel-spacing tunable multiwavelength fiber ring laser by using two segments of polarization-maintaining fiber (PMF) is experimentally demonstrated. By adjusting the polarization controllers, the wavelength spacing could be efficiently switched among 0.48, 0.73, and 1.45 nm. Moreover, we also analyzed theoretically the equivalent Lyot birefringence fiber filter with two segments of PMF. Theoretical prediction was verified by experimentally obtained multiwavelength outputs.

Tunable multiwavelength SOA-fiber ring laser based on Sagnac loop mirror incorporating few-mode high birefringence fiber

A tunable multiwavelength fiber ring laser based on a semiconductor optical amplifier and Sagnac loop mirror incorporating a piece of few-mode high birefringence fiber (FM-HBF) is proposed and experimentally demonstrated. It is accomplished by simply adjusting a polarization controller in the Sagnac loop mirror because birefringence of the FM-HBF is polarization dependent. Tunable multiwavelength operation up to 11 oscillating lines at about 2.1 nm interval is stably achieved with an optical side-mode suppression ratio over 35 dB.

Tunable Multiwavelength Fiber Ring Lasers Based on an Opto-VLSI Processor

We propose and experimentally demonstrate the principle of a tunable multiwavelength fiber ring laser based on the use of an opto-very-large-scale-integration (Opto-VLSI) processor in conjunction with an erbium-doped fiber amplifier and a semiconductor optical amplifier. Multiple wavelength channels within the gain range of the optical amplifiers can independently be generated, tuned and/or switched on/off, through applying appropriate phase holograms onto the Opto-VLSI processor. A tunable five-wavelength fiber ring laser of output power of around +6 dBm per channel and a sidemode suppression ratio (SMSR) greater than 30 dB is demonstrated. The tunable multiwavelength fiber lasers have excellent stability at room temperature.

Polarization controlled tunable multiwavelength SOA-fiber laser based on few-mode polarization maintaining fiber loop mirror

A tunable multiwavelength fiber ring laser based on a semiconductor optical amplifier and few-mode polarization maintaining fiber (FM-PMF) loop mirror is proposed and experimentally demonstrated. It is accomplished by simply adjusting a polarization controller (PC) next to the FM-PMF in the loop arm for the polarization-dependent mode excitation in the FM-PMF and the resulting effective refractive index change. In addition, the undesirable dependence of the transmission loss of the FM-PMF loop mirror on the rotation angle of the PC in the loop arm can be reduced by using a fiber coupler with unequal coupling ratio instead of equal coupling ratio. Stable and tunable multiwavelength operation with up to 11 lasing lines at about 1.5 nm interval is achieved with the power deviation less than 2 dB and optical signal to noise extinction ratio over 35 dB.

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.

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.

Continuous true-time-delay beamforming employing a tunable multiwavelength fiber ring laser source with equally increased or decreased wavelength spacing

The authors propose a true-time-delay system for wideband continuous phased array beamforming using a chirped grating-based true-time-delay beamforming network incorporating a novel multiwavelength tunable fiber ring laser with equally increased or decreased wavelength spacing. The wavelength of each lasing is determined by the fiber Bragg grating in the laser cavity and tuned by compressing or stretching the fiber Bragg grating. For simultaneously achieving N tunable lasings, N fiber Bragg gratings are used. To ensure wavelength tuning with equally increased or decreased wavelength spacing, the N fiber Bragg gratings are mounted on an organic plastic plate with angles between adjacent gratings such that the tuning forces applied to the gratings experience equal increments. Time delays with equally increased or decreased time-delay difference for the equally spaced wavelengths are obtained when the modulated light waves are reflected at different locations of a linearly chirped grating. A four-channel chirped-grating-based true-time-delay system using the proposed light source for continuous beamsteering at microwave frequencies up to 10 GHz has been constructed and demonstrated.

Active mode locking of tunable multi-wavelength fiber ring laser

We report an active mode-locked tunable multiple-wavelength fiber laser constructed using a unidirectional ring cavity combined with an amplitude modulator and a single sampled fiber Bragg grating (SFBG). Simultaneous generation of up to six-wavelength picosecond pulses with identical repetition rate and a wavelength spacing of about 1.6 nm (200 GHz) is demonstrated. The spectral width and side-mode suppression ratio are 0.01 nm and 40 dB for all the wavelengths. The average output power is 4.5 dBm and the supermode noise suppression is more than 40 dB. The equal-step wavelength tuning over a range of 1.6 nm for all the wavelengths has also been achieved by applying tension to the SFBG.