Multiwavelength Erbium-doped Fiber Ring Laser Research Articles

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.

Tunable and switchable multiwavelength erbium-doped fiber ring laser based on a modified dual-pass Mach-Zehnder interferometer

A tunable and switchable multiwavelength erbium-doped fiber ring laser based on what we believe to be a new type of tunable comb filter is proposed and demonstrated. By adjusting the polarization controllers, the dual-function operation of the channel-spacing tunability and the wavelength switching (interleaving) can be readily achieved. Up to 29 stable lasing lines with 0.4 nm spacing and 14 lasing wavelengths with 0.8 nm spacing in 3 dB bandwidth were obtained at room temperature. In addition, the lasing output, including the number of the lasing lines, the lasing evenness, and the lasing locations, can also be flexibly adjusted through the wavelength-dependent polarization rotation mechanism.

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.

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.

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.

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.

Room temperature multiwavelength erbium-doped fiber ring laser using a highly nonlinear photonic crystal fiber

A multiwavelength laser source is demonstrated with a high power erbium-doped fiber amplifier as the gain medium. A highly nonlinear photonic crystal fiber (PCF) is inserted in the ring cavity to provide nonlinear gain by four-wave mixing. A Sagnac loop is incorporated in the ring cavity serving as a comb-like multichannel filter. The comparison between fiber ring laser without PCF and with PCF shows that the highly nonlinear PCF can generate a larger number of excited wavelengths and help stabilize the output power.

Optimization of the multiwavelength erbium-doped fiber laser in a unidirectional cavity without an isolator

A highly uniform multiwavelength erbium-doped fiber ring laser with an intracavity 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. Fifteen lasing lines with wavelength spacing of 0.9 nm appear simultaneously and stably with power differences less than 2 dB and side-mode suppression ratio higher than 32 dB. In addition, the proposed cavity can support unidirectional operation without optical isolators. An output power difference of about 20 dB is realized between the counterclockwise and clockwise directions, which is almost independent of the pump power and lasing wavelengths. (c) 2005 Society of Photo-Optical Instrumentation Engineers.

Switchable multiwavelength erbium-doped fiber ring laser with a multisection high-birefringence fiber loop mirror

We proposed and demonstrated a new concept of switchable multiwavelength erbium-doped fiber ring laser with a multisection high-birefringence fiber loop mirror (HiBi-FLM). The HiBi-FLM results in the laser operating on different allowed wavelengths. The wavelength switching can be achieved by modifying the reflection spectrum of HiBi-FLM through two polarization controllers. The experiment demonstrates the switchable lasing operation within the random combination of three wavelengths, as well as with a large (/spl sim/40 dB) output signal to background noise ratio.

Multiwavelength erbium-doped fiber ring laser incorporating an SOA-based phase Modulator

A novel room-temperature multiwavelength erbium-doped fiber (EDF) laser is demonstrated. Stable multiwavelength lasing at room temperature is realized by incorporating a semiconductor optical amplifier (SOA)-based phase modulator in the laser cavity. The SOA is biased below the transparent point with a sinusoidal signal applied to achieve phase modulation, to suppress the homogenous line broadening of the EDF. Stable multiwavelength lasing with wavelengths up to 26 and wavelength spacing as small as 0.19 nm is demonstrated at room temperature.

Multiwavelength erbium-doped fiber ring laser source with a hybrid gain medium

Erbium-doped fiber is a gain medium exhibiting homogeneous line broadening at room temperature, while a semiconductor optical amplifier has a dominant feature of inhomogeneous line broadening. In this work, a semiconductor optical amplifier is incorporated into the cavity of an erbium-doped fiber ring laser to form a hybrid gain medium. Theoretical analysis shows that such a gain medium supports stable multi-wavelength operation. A stable 24 wavelength lasing operation with wavelength spacing of 0.5 nm and signal-to-noise ratio better than 42 dB is observed experimentally at room temperature.

Room-temperature multiwavelength erbium-doped fiber ring laser employing sinusoidal phase-modulation feedback.

An effective method for achieving a room-temperature multiwavelength erbium-doped fiber ring laser is presented. Simultaneous multiwavelength lasing with 0.5-nm intervals is achieved both experimentally and theoretically by addition of sinusoidal phase modulation in the ring cavity to prevent single-wavelength oscillation.

Optical filter design for multiwavelength erbium-doped fiber ring lasers

A model for designing optical filters on multiwavelength erbium-doped fiber ring lasers is proposed. For the given amplifier parameters and output spectrum the model provides the required cavity transfer function, from which the maximum output coupling ratio and the optical filter spectral shape can be obtained. Standard propagation and rate equations of a homogeneous medium are employed for the erbium fiber analysis. The calculated cavity transfer function is tested by analyzing the obtained erbium-doped fiber ring laser employing a previously presented model. The effectiveness of the method is tested with a nine-line signal on the 1525–1565 nm range.

High-performance adjustable room temperature multiwavelength erbium-doped fiber ring laser in the C-band

Experimental realization of a high-power and highly uniform multiwavelength cw erbium-doped fiber ring laser with an intra-cavity frequency shifter and line spacing of 100 GHz is presented. The extremely flat response is achieved by optimizing the laser cavity losses, pump power and length of the active fiber. A simple method of shifting the laser emitting spectral region, which preserves the spectral output flatness, is demonstrated. The laser may be easily switched between two spectral regions of 1538–1548 and 1543–1559 nm. In both ranges, the power uniformity is better than 3 dB.

Efficient multi-wavelength fiber laser operating in L-band

In this paper, an efficient L-band multi-wavelength erbium-doped fiber ring laser is demonstrated by recycling backward 1550 nm band amplified spontaneous emission as secondary pump source for the unpumped EDF section. The lasing threshold is reduced and the slope efficiency is improved. A piece of multimode fiber is used as a spatial mode-beating filter. By adjusting the polarization state of the light, the number of lasing wavelength and their spaces are controlled. In dual-wavelength laser, the power of each channel is 4 mW with 40 dB side-mode-suppression-ratio.