Dual-wavelength Erbium-doped Fiber Ring Laser Research Articles

Study on Dual-Wavelength Wide-Spectrum Erbium-Doped Fiber Ring Laser for Optical Fiber Interferometric Sensing System

In this paper, a novel dual-wavelength wide-spectrum erbium-doped fiber ring laser (EDFRL) for optical fiber sensing system is proposed and experimentally demonstrated. The output of EDFRL is theoretically simulated and classified depending on the theoretical analysis of laser threshold condition into “excited state” and “nonexcited state”. The influence of pump wavelength, fiber laser configuration, EDF length and output coupling ratio of EDFRL is discussed. The EDFRL pumped at 1480 nm wavelength and backward-pumped mode could achieve the stable maximum wide-spectrum output power. The output power fluctuation is lower than 0.06 dB and the center wavelengths shift is less than 0.01 nm. The practicability of EDFRL in a hybrid M-Z and Sagnac interferometer optical fiber sensing system is demonstrated through the comparison of SLD and EDFRL. Consequently, the EDFRL proposed in this study is expected to replace the traditional SLD in the optical fiber interferometric sensing system at a lower cost.

Simultaneous Measurement of Temperature and Relative Humidity Using a Dual-Wavelength Erbium-Doped Fiber Ring Laser Sensor

A fiber ring laser sensor setup utilizing fiber Bragg gratings (FBGs) for simultaneous measurement of ambient temperature and relative humidity (RH) is presented. Two FBGs are incorporated as tunable filters for a dual-wavelength laser emission, where one FBG was coated with polyimide (PI) in order to achieve sensitivity to RH changes, while the other bare FBG was used for temperature sensing. An increase in RH would induce a strain on the grating, which results in a variation in the resonance wavelength of the PI-coated FBG. This causes a shift in the laser emission wavelength. Being insensitive to RH changes, the bare FBG was employed to measure temperature. The dual-wavelength fiber ring laser sensor created, and thus allows to determine simultaneous measurement of RH and temperature. The RH sensitivities observed by the PI-coated FBG to RH and temperature are 3.6 pm/%RH and 12.15 pm/°C. The temperature sensitivity of the bare FBG was observed to be 9.6 pm/°C. The main advantage of the proposed setup is an optical signal to noise ratio (OSNR) higher than 55 db 3 dB bandwidth less than 0.02 nm, which points out efficient capabilities for both precise sensing and remote detection applications.

Highly sensitive dual-wavelength fiber ring laser sensor for the low concentration gas detection

A highly sensitive low concentration gas sensor based on dual-wavelength Erbium-doped fiber ring laser (EDFRL) is designed and demonstrated. The dual-wavelength lasing output is introduced by a tunable Fabry-Perot (F-P) filter and a fiber Bragg grating (FBG) due to the mode competition as they both share a same EDF gain medium. One wavelength at 1530.37 nm serving as the sensing element is inserted by a hollow core photonic crystal fiber (HCPCF) gas cell which can bring in much more power change when the cavity loss slightly varies while the other wavelength at 1532.38 nm acting as a reference. Experimental results show that the sensor can achieve a good linear response (R2 = 0.9864) to acetylene concentration variation and a minimum detection limit (MDL) of 10.42 ppmV at 20 s response time, which is the lowest to our best knowledge and improving 6.44 times than that of single-wavelength EDFRL based. Moreover, the absolute detected error induced by the power fluctuation (< 0.1 dB) is less than 1.78% over more than 300 s of observation.

Switchable dual-wavelength single-longitudinal-mode erbium fiber laser utilizing a dual-ring scheme with a saturable absorber

In this work, we propose and demonstrate a switchable dual-wavelength erbium-doped fiber (EDF) ring laser with stable single-longitudinal-mode (SLM) output. Here, a dual-ring (DR) structure with an unpumped EDF of 2 m is designed to achieve SLM oscillation. Five fiber Bragg gratings (FBGs) are applied in the laser cavity serving as the reflective element to generate different dual-wavelength outputs. In the measurement, six sets of generated dual-wavelengths with various mode-spacing (Δλ) can be achieved via the five FBGs. Additionally, the stability performance of the proposed EDF DR laser is also demonstrated.

Development of dual-wavelength fiber ring laser and its application to step-height measurement using self-mixing interferometry.

A dual-wavelength erbium-doped fiber (EDF) ring laser was developed and its application to step-height measurement using two-wavelength self-mixing interferometry (SMI) was demonstrated. The fiber laser can emit two different wavelengths without any laser mode competition. It is composed of two EDF laser cavities and employs fiber Bragg gratings to determine which wavelengths are emitted. The step heights can be measured using SMI of the two wavelengths, and the maximum height that can be measured is half the synthetic wavelength of the two wavelengths. A step height of 1mm was constructed using two gauge blocks and then measured using the laser. The measurement was repeated ten times, and the standard deviation of the measurements was 2.4nm.

Selectable dual-wavelength erbium-doped fiber laser with stable single-longitudinal-mode utilizing eye-type compound-ring configuration

In this paper, a tunable dual-wavelength erbium-doped fiber (EDF) ring laser with stable single-longitudinal-mode (SLM) under a tuning range of 1530.0–1560.0nm is proposed and demonstrated. Here, the mode spacing of lasing dual-wavelength from 1.0 to 30.0nm can be selected arbitrarily in any wavelength position. To accomplish the SLM output, the eye-type compound-ring scheme is proposed inside ring cavity for suppressing the multi-longitudinal-mode (MLM) highly. The entire measured output power and optical signal to noise ratio (OSNR) of each dual-wavelength are larger than −13.3dBm and 60dB respectively. In addition, the output stability measurement of proposed EDF laser is also performed and analyzed.

Switchable narrow linewidth single-longitudinal mode erbium fiber laser by using saturable-absorber filter and cavity loss control

A simple single-longitudinal-mode (SLM) dual-wavelength erbium-doped fiber ring laser is proposed and demonstrated at first by using an arrayed waveguide grating (AWG) as wavelength filter. Owing to the two sub-ring cavities with different cavity losses, equalized dual-wavelength output can be achieved easily utilizing cavity loss control. The SLM operation is guaranteed by self-injection feedback mechanism under low pump power. In order to improve the dual-wavelength output power, a saturable-absorber (SA) based on a 4m unpumped EDF is inserted into the main cavity to guarantee the SLM operation under high pump power. The performance of the laser outputs has been experimental studied and all the output wavelengths have a narrow linewidth output.

A switchable single- and dual-wavelength erbium fiber ring laser in single-longitudinal-mode operation

A simple stable single-longitudinal-mode (SLM) single- and dual-wavelength erbium-doped fiber ring laser using an arrayed waveguide grating as the wavelength filter is proposed and demonstrated. SLM operation is guaranteed by a saturable-absorber-based auto-tracking filter. A 40/60 optical coupler is used to form two imbalanced loss cavities in the fiber laser initially, and single- and dual-wavelength operation can be changed by properly modifying the variable optical attenuator. The side mode suppression ratios of the laser outputs are higher than 60 dB. Through switching the two fiber optical switches, the dual-wavelength spacing is tuned from the narrowest 0.82 nm to the widest 12.05 nm, which offers potential uses in the generation of terahertz (THz) radiation.

Switchable dual-wavelength erbium-doped fiber ring laser with tunable wavelength spacing based on a compact fiber filter

Abstract In this paper, using a compact fiber filter (CFF), we demonstrate a dual-wavelength erbium-doped fiber ring laser with tunable wavelength spacing. The two oscillation wavelengths are specified by a fiber modal interferometer (MI) and a fiber Bragg grating (FBG) embedded in the MI, which consists of the CFF. Due to the deeply saturated spectral hole-burning (SHB) effect in the erbium-doped fiber, stable dual-wavelength operation is achieved at room temperature and the wavelength spacing can be tuned from 9.29 nm to 11.11 nm continuously when the strain applied to the CFF is changed. By adjustment of the attenuator in the cavity, the laser can operate in dual-wavelength or in wavelength switching modes.

A stable single-longitudinal-mode dual-wavelength erbium-doped fiber ring laser with superimposed FBG and an in-line two-taper MZI filter

A simple approach to fabricate a stable single-longitudinal-mode (SLM) dual-wavelength erbium-doped fiber ring laser with one superimposed fiber Bragg grating (FBG) is proposed and demonstrated. The superimposed FBG is fabricated by the dual-exposure method for wavelength selection. A home-made in-line two-taper Mach–Zehnder interferometer is incorporated to balance the intra-cavity loss for the wavelengths. The SLM operation is guaranteed by a feedback fiber loop and saturable absorber. A stable dual-wavelength SLM fiber ring laser with a wavelength spacing of approximately 8.53 nm is experimentally realized. The optical signal-to-noise ratio of the laser output is over 50 dB and the linewidth of each wavelength measured by the delayed self-heterodyne method is 9.67 kHz and 9.07 kHz, respectively. The proposed scheme offers the possibility for difference frequency generation of terahertz radiation.

Switchable Dual-Wavelength PM-EDF Ring Laser Based on a Novel Filter

A stable and switchable dual-wavelength polarization-maintaining erbium-doped fiber ring laser is proposed and demonstrated experimentally by using a novel filter, which is formed from dual-pass Mach-Zehnder interferometer incorporating a sagnac loop. By adjusting the polarization controllers, the output laser can be switched between single- and dual-wavelength. The wavelength spacing of the dual-wavelength can be tuned from 0.084 to 4.26 nm. Its 3-dB bandwidth and side mode suppression ratio are less than 0.015 nm and higher than 64 dB, respectively. In addition, the peak power fluctuation and wavelength shift are monitored to be less than 0.5 dB and 0.01 nm during an hour, respectively. The characteristics of the novel filter in experimental measurement accord with the result of theoretical analysis.

Photonic generation of microwave signal by beating a dual-wavelength single longitudinal mode erbium-doped fiber ring laser based on the polarization maintaining fiber bragg grating

A single-longitudinal-mode (SLM) dual-wavelength erbium-doped fiber (EDF) ring laser based on one polarization maintaining fiber Bragg grating (PMFBG) is demonstrated.Due to the polarization hole burning enhanced by the PMFBG, the laser can be designed to operate in stable dual-wavelength oscillation with a wavelength spacing of 0.182 nm at room temperature by adjusting a polarization controller. A section of unpumped EDF acting as a saturable absorber and a feedback fiber loop is used to ensure SLM operation in each of the two lasing lines. A microwave signal at 22.807 GHz is obtained by beating the dual-wavelength fiber laser at a photodetector. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:347–351, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27280

Stable dual-wavelength erbium-doped fiber ring laser with switchable spacing employing controllable channel loss

A stable dual-wavelength erbium-doped fiber ring laser with switchable spacing is proposed and experimentally demonstrated. An arrayed waveguide grating (AWG) incorporating two fiber optic switches (OS) is used to as the wavelength selector. The ring cavity is divided into two cavities by a 30:70 optical coupler. Equalized dual-wavelength outputs are achieved by controlling the variable optical attenuator (VOA) inserted in the lower loss cavity. The wavelength spacing can be tuned from 0.80 to 12.05 nm. The fiber laser has good optical quality with maximum power fluctuation of 1.5 dB and side mode suppression ratios (SMSRs) higher than 71 dB.

Numerical model of dual-wavelength erbium-doped fiber ring laser based on gain-equilibrium method

A novel numerical model of the dual-wavelength fiber ring lasers utilizing gain-equilibrium method is presented by developing the two level, homogeneous Giles model. To obtain the simulation method, the gain equilibrium condition is derived and modified to adapt to the iterative procedure in simulations. This condition is confirmed by both the numerical and experimental results, which indicate that the cavity losses of both wavelength channels play important roles in maintaining stable dual-wavelength emitting. The tolerant loss-bias is 0.05 dB in simulations and 0.4 dB in experiments, respectively. The difference between numerical and experimental results reveals that the inhomogeneous linewidth broadening of EDF contributes mostly to the improved power stability, but the loss vibrations play an important role in this effect.

Photonic generation of microwave signal using a dual-wavelength erbium-doped fiber ring laser with CMFBG filter and saturable absorber

A simple approach for photonic generation of microwave signal using a dual-wavelength single-longitudinal-mode (SLM) erbium-doped fiber (EDF) ring laser is proposed and demonstrated. For the first time as we know, a chirped moiré fiber Bragg grating (CMFBG) filter with ultra-narrow transmission band and a chirped fiber Bragg grating (FBG) are used to select the laser longitudinal mode. The stable SLM operation of the fiber laser is guaranteed by the combination of the CMFBG filter and 3m unpumped EDF acting as a saturable absorber. Stable dual-wavelength SLM fiber laser with a wavelength spacing of approximately 0.140nm is experimentally realized. By beating the dual-wavelength fiber laser at a photodetector, photonic generation of microwave signal at 17.682GHz is successfully obtained.

Switchable dual-wavelength erbium-doped fiber ring laser assisted with four-wave mixing of dispersion-shifted fiber

We experimentally demonstrate two types of stable dual-wavelength EDF fiber ring lasers assisted with four-wave mixing of dispersion-shifted fibers to suppress the homogeneous broadening of EDF. Moreover, by using a Sagnac loop interferometer without circulator, the proposed fiber laser is cost-effective and has switchable resonance wavelength.

Correlated Photon-Pair Source for Secured $C$-Band Quantum Communications

We have experimentally investigated and shown evidence of correlated photon-pair generation based on coupled intracavity four-wave mixing (FWM) in a dual-wavelength erbium-doped fiber ring laser operating in the fiber-optic communication <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> -band regime. In the coupled FWM process, the pump photons are both involved in the absorption and stimulated emission, which generate signal and idler wavelengths simultaneously. The correlation experiment was performed with various photon count levels in the order of hundreds of photons/s at each channel. The photon number of channel was less than 0.1/pulse and the maximum coincidence to single counts ratio was approximately 12% with a Gaussian profile in the accumulated counts.

Tunable dual-wavelength erbium-doped fiber ring laser covering both C-band and L-band for high-speed communications

A simple, continuously tunable dual-wavelength erbium-doped fiber ring laser (TDEDFL) structure for applications in high-speed communication systems is proposed and experimentally demonstrated. The dual-wavelength tuning range is 58 nm covering both the C-band and L-band from 1547 to 1605 nm. We can not only obtain a 45% improvement over previously reported tuning ranges, but also tune the wavelength of each lasing output independently. The power equalization of the dual-wavelength outputs is less than 1.5 dB. We obtain extremely stable power variation and wavelength fluctuation at room temperature. Using this fiber laser, a 10-Gb/s data transmission over a 25-km single-mode fiber (SMF) can be made available with a power penalty of 0.5 dB is demonstrated with this laser.

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.

Dual-wavelength switchable erbium-doped fiber ring laser based on merged sagnac and intermodal interferences in sagnac loop mirror

A simple but novel concept of switchable dual-wavelength erbium-doped fiber ring laser is proposed and experimentally demonstrated. It is based on a Sagnac loop mirror incorporating a high birefringence few-mode fiber and polarization controller (PC). Since its transmission properties depend on the PC state, the proposed fiber ring laser can operate in the random combination of two wavelengths by adjusting only the PC settings. The potential lasing lines are determined by simultaneous occurrence of the Sagnac and intermodal interferences in the Sagnac loop mirror. All lasing emissions have the optical signal to noise extinction ratio higher than 45 dB and their power fluctuations lower than 0.5 dB.