Dual-wavelength Laser Output Research Articles

Performance improvement of dual-GSA-wavelength pumped heavily-doped 3 μm Er:YSGG laser by using wing-pumping method

The dual-GSA-wavelength pumping combined with wing-pumping method has been successfully used to improve the output performance of a 30 at.% Er:YSGG laser at 3 μm. According to the GSA spectrum of 4I15/2→4I9/2 transition at 0.8 μm, two pump wavelengths of 785 and 798 nm are used to verify the effectiveness of dual-GSA-wavelength pumping, with 798 nm overlapping an absorption peak, while 785 nm deviating from the absorption peak of Er:YSGG crystal. With regard to the 798/976 nm dual-wavelength pumping, the output power fails to maintain a continuous growth trend with the dual-wavelength pump power in comparison with the single-wavelength pumping at 976 nm. This indicates the influence of thermal effects on the heavily erbium-doped material is more severe, resulting in a significant reduction in the available pump power range. When the 785 nm with weak absorption is used for dual-wavelength pumping, the output power achieves a nearly linear increase within a larger range of dual-wavelength pump power. The achievable maximum output power is 662 mW for the 785/976 nm dual-wavelength pumping, respectively increased by 13.2 % and 64.7 % compared to the achievable maximum output power obtained in 976 nm single-wavelength and 798/976 nm dual-wavelength pumping. It is also found that the introduction of 785 nm pump light would lower the threshold for achieving dual-wavelength laser output for the Er:YSGG laser. The dual-GSA-wavelength pumping combined with wing-pumping method provide an effective solution for improving the performance of heavily erbium-doped lasers at 3 μm.

High-power and efficient orthogonally-polarized dual-wavelength Nd:YLF laser

We demonstrate an actively Q-switched orthogonally-polarized dual-wavelength laser at 1047.4 nm and 1053.4 nm with high average power and high efficiency. The gain competition between dual-wavelength lasers is effectively suppressed by using two Nd:YLF crystals as laser gain medium. Investigations concerning different resonator structures and pulse repetition frequency were conducted to achieve the best performance of this laser. Under the total incident pump power of 32.7 W, a maximum dual-wavelength laser output power of 13.4 W is obtained at the pulse repetition rate of 30 kHz, corresponding to an optical conversion efficiency of 41%. For 1047.4 nm and 1053.4 nm lasers, the maximum average output powers are as high as 7.6 W and 5.8 W, respectively, and they also demonstrate good output power stability and beam quality. This orthogonally-polarized dual-wavelength laser has significant practical applications in various fields, such as terahertz radiation generation, precision metrology, laser radar, and spectral analysis.

Tunable and Switchable Dual-Wavelength SLM Narrow-Linewidth Fiber Laser with a PMFBG-FP Filter Cascaded by Multi-Ring Cavity

A single longitudinal mode (SLM) dual-wavelength switchable erbium-doped fiber laser (DW-EDFL) based on polarization-maintaining fiber Bragg grating Fabry–Perot cavity (PMFBG-FP) cascaded multiple sub-ring cavities (MSCs) is proposed. A PMFBG-FP with a narrow-band transmission peak and MSCs was implemented as an optical filter to achieve stable dual-wavelength laser output and guaranteed SLM status. By stretching the PMFBG, a highly stable dual-wavelength tunable output could be achieved with a maximum tuning interval of 0.17 nm. The optical signal-to-noise-ratio (OSNR) at dual-wavelength lasing was higher than 57 dB, and the optimal wavelength and power fluctuations within 0.5 h were 0.01 nm and 0.79 dB, respectively. Meanwhile, the measured linewidths of each wavelength were 1.55 kHz and 1.65 kHz, respectively. The measured polarization states of the two laser wavelengths were linear and orthogonal, with a degree of polarization (DOP) of nearly 100%.

Erbium-doped fiber laser with switchable wavelength generation based on tunable filter and dual-pass mach-zehnder filter incorporated with fiber delay line

A wavelength switchable erbium-doped fiber laser incorporated with a tunable filter and dual-pass Mach–Zehnder interferometer (MZI) was designed and experimentally demonstrated. The erbium-doped fiber was used as the gain medium for the fiber laser and the laser working threshold was 92 mW. The dual-pass MZI was fabricated using three optical couplers (OCs) and the variable fiber delay line. A tunable filter was used for laser tuning and it was combined with two OCs to construct a subsidiary cavity. A tunable and stable single- and dual-wavelength laser output was obtained in the experiment. In the case of single-wavelength laser output, the tuning span was in the range of 1527.6–1562.4 nm with an interval of 1.2 nm. Additionally, the side-mode suppression ratio (SMSR) was greater than 37.45 dB. In the case of dual-wavelength laser emission, the lasers were tuned from 1540.7 and 1541.6 nm to 1560.8 and 1561.2 nm, respectively. The stability of the single-, dual-and triple-wavelength laser output was evaluated and the power fluctuation was less than 1.36, 1.34, and 1.37 dB, respectively. Finally, quadruple- and quintuple-wavelength laser outputs were achieved by adjusting the loss of the intra-cavity.

Multi- and dual-wavelength Thulium-doped fluoride fiber laser assisted by four-wave mixing in S-band region

In this work, multi-wavelength lasing in the S-band region using a Sagnac loop filter in a thulium-doped fluoride fiber laser (TDFFL) was demonstrated for the first time. The Sagnac loop served as a comb-like wavelength filter, while a 10-km long dispersion compensating fiber (DCF) was utilized to induce the four-wave mixing (FWM) effect in the cavity. The FWM effect was used to suppress mode competition in the TDFFL as well as to enhance the number of lasing lines. At its optimum polarization state, 17 stable lasing lines at peak powers of less than 10 dB from the highest peak power were observed, with these lasing lines having a uniform wavelength spacing of 0.23 nm. The multi-wavelength operation exhibited minimal wavelength drifts and power fluctuations of less than 0.01 nm and 1.2 dB respectively. A tunable dual-wavelength laser output was also demonstrated, with a constant wavelength spacing throughout the tuning range.

1064/1342 nm dual-wavelength double electro-optical Q-switched Nd:YVO4 laser

An all-solid-state Nd:YVO4 laser producing dual-wavelength of 1064/1342 nm was designed, which took a plan of double RTP (RbTiOPO4) electro-optic Q-switch of 1064 nm and 1342 nm, by controlling the voltage of double RTP crystals to control the output laser power ratio of dual-wavelength. When the repetition rate is 10 kHz, the 1064/1342 nm dual wavelength laser output with 1.6/1.6 W, power ratio of 1:1, and basically overlapping pulse peak time is obtained by changing the crystal voltage.

Design and analysis of a range-extended acidity detector based on a Nile red laser with tandem cuvette system

A range-extended acidity detector based on Nile red was designed and analyzed in this work. In light of the good lasing property and solvatochromism characteristic of Nile red/ethanol solution, we have obtained laser spectra of sulfuric acid in different concentrations doped in this substrate. Moreover, to expand the acidity detection range, we proposed a tandem cuvette system containing rhodamine 6G/ethanol and Nile red/ethanol. Consequently, the detection range could be enlarged from 26 nm to 40 nm, by changing not only the wavelength peak but also by the intensity ratio of dual-wavelength laser output. In addition, by changing the detection and substrate materials, the whole detection range could be expanded, and therefore a wide range of applications in polarity and acidity detection could be implemented via this method.

All-fibre Mach–Zehnder interferometer based on seven-core and coreless fibres for generating stable wavelength-switchable laser

ABSTRACTIn order to realize a wavelength-tuneable fibre-laser output, a ring-cavity erbium-doped fibre laser based on an all-fibre Mach–Zehnder interferometer (MZI) is proposed and experimentally tested. The MZI consists of a single-mode fibre, two segments of coreless fibre, and a seven-core fibre. For the proposed fibre laser, the length of the gain medium is 4 m and the lasing threshold is 75 mW. By adjusting the loss of the laser cavity, switchable single-wavelength laser emission is realized across the range of 1527.6–1549.9 nm and the wavelength interval is less than 2.4 nm; the peak power difference of each lasing wavelength is less than 7.9 dB. Tuneable dual- and three-wavelength laser outputs were obtained by adjusting the polarization controller. The 3-dB linewidth was less than 0.57 nm. The single- and dual-wavelength laser output power fluctuations were less than 1.4 and 1.7 dB, respectively, when monitored over a period of 30 min.

Wavelength-switchable erbium-doped fiber laser based on femtosecond FBG inscribed on fiber core and cladding through the coating

Wavelength-switchable and multiple-wavelength outputs from fiber laser systems have many potential applications but, at present, methods for their generation are quite complex. Here we propose a simple approach, demonstrating a dual-wavelength switchable erbium-doped fiber laser that incorporates a single fiber Bragg grating (FBG), fabricated by a femtosecond laser in a plane-by-plane inscription method through a fiber coating, for a switchable 1564.66 and 1562.87 nm dual-wavelength laser operation. An 800 nm femtosecond pulsed laser acts as the inscription laser, focused by a 63× oil lens, fabricating a first-order FBG with an interval of 541 nm directly, on both the fiber core and cladding, through the polyimide coating. A 4 m-long erbium-doped fiber was selected as the gain medium. A lasing threshold of 66 mW was used in the experiment, and a switchable laser with stable single- and dual-wavelength outputs was achieved by adjusting a polarization controller. We were able to generate two different single-wavelength lasers with power fluctuations lower than 0.09 dB when measured over 40 min. In addition, dual-wavelength laser output could be obtained with power shifts of less than 0.9 dB at 26 °C.

Generation of Four-Wave Mixing in a Highly Non-Linear Optical Fiber Using a Tunable Dual Wavelength Fiber Laser Source

In this paper, we demonstrate a Four Wave Mixing (FWM) effect in a highly nonlinear single mode optical fiber. A tunable dual-wavelength fiber laser is used to provide the pump and signal probe to generate partially degenerate FWM. Calculations using coupled differential equations and experimental results in the generation of FWM were analyzed. We observed that FWM conversion efficiency depends more significantly on the wavelength detuning between pump and signal wavelength as compared to zero-dispersion wavelength. The tunability is achieved using an arrayed waveguide grating which provides different wavelength combinations of the dual-wavelength fiber laser output and can be tuned from 1530.47nm to 1548.61nm with a spacing of 100GHz. The highly nonlinear fiber has a nonlinear coefficient, γ of 10.8 W-1km-1. Hence, to achieve higher FWM output power the pump power of the dual wavelength fiber laser has to be higher than that of the signal probe. The optimum measured values of pump and signal power are +13.3dBm and +5dBm respectively, limited buy the current experimental setup.

A highly stable and switchable dual-wavelength laser using coupled microfiber Mach-Zehnder interferometer as an optical filter

The generation and switching of dual-wavelength laser based on compact coupled microfiber Mach-Zehnder interferometer (CM-MZI) is reported. The CM-MZI is constructed by overlapping two portions of a single tapered optical fiber which has a diameter of 9μm as to create multi-mode interference and also to produce spatial mode beating as to suppress mode competition in the homogeneous gain medium. The system is able to generate a dual-wavelength laser output that can be switched with the aid of the polarization rotation technique. Four dual-wavelength oscillation pairs are obtained from the interference fringe peaks of the CM-MZI comb filter with a switched channel spacing of 1.5nm, 3.0nm, and 6.0nm. The wavelength spacing is stable at different pump powers. The lasing wavelength has a 3-dB linewidth of about 30pm and peak-to-floor ration of about 55dB at a pump power of 38mW.

Dual-Wavelength Laser Output in Nd3+/Yb3+Co-Doped Phosphate Glass Fiber Under 970 nm Pumping

We report the demonstration of dual-wavelength laser output originating from excited Nd 3+ ions and Yb 3+ ions in Nd 3+ /Yb 3+ co-doped phosphate glass fiber under 970-nm laser diode pumping. Using a free-space coupling method, laser bands at 1028 and 1053 nm were observed in a 35-cm-long fiber with the corresponding lasing thresholds of 4.3 and 31.5 W at room temperature. Emission and lasing spectra under different pump powers were tested by the optical spectrum analyzer. The 1053-nm laser threshold was found to be temperature sensitive. The mechanism of Yb 3+ → Nd 3+ energy transfer under 970 nm pumping was explored. It was proposed that Yb 3+ → Nd 3+ energy transfer process with the participation of phonon resulted in 1053-nm laser of Nd 3+ ions in this co-doped fiber under 970 nm pumping.

Multiple weak-line laser operation from Nd:YAG 4F3/2-4I13/2 translation in ceramic and crystal

Laser diode end-pumped Nd:YAG based multiple weak-lines laser from 4F3/2-4I13/2 translation is reported. Fluorescence spectra for both Nd:YAG crystal and ceramic are present. Simple two-mirror cavity with reasonable optical coating is used for multiple weak-line laser operation around 1.3 and 1.4 μm. The variations of laser output and spectra with the pump power are compared experimentally between 1.0 at.% Nd3+ doped Nd:YAG ceramic with 3 mm×3 mm×7.5 mm in size and 0.8 at.% Nd3+-doped Nd:YAG crystal with 3 mm×3 mm×8 mm in size. First, 1338 and 1356 nm dual-wavelength laser outputs are achieved using output coupler with transmittance values of 9.6%, 6.2%, 2.4% and 1.8% at 1338, 1356, 1414 and 1444 nm, respectively. Under low pump power around the threshold, the 1356 nm single wavelength laser is obtained. With increasing the pump power, the laser with a wavelength of 1338 nm appears first in the ceramic. At an incident pump power of 11.8 W, a 1338 and 1356 nm dual-wavelength laser with an output power of 3.7 W and an intensity ratio of 1 : 5 for crystal, and a 1338 and 1356 nm dual-wavelength laser with an output power of 3.5 W and an intensity ratio of 1:3 for ceramic are obtained. Replacing the output couplers with transmittance values of 15.4%, 6.5%, 1.1% and 0.8% at wavelengths of 1338, 1356, 1414 and 1444 nm, respectively, 1356 and 1414 nm dual-wavelength laser outputs are achieved. Under the low pump power, even triple-wavelength (1356, 1414 and 1444 nm) laser is obtained. With increasing the pump power, the intensities of 1414 and 1444 nm wavelengths turned down and the 1444 nm wavelength disappears first in ceramic. At an incident pump power of 11.8 W, a 1356 and 1414 nm dual-wavelength output power of 3.56 W with intensity ratio of 44 : 1 for crystal and a 1356 and 1414 nm dual-wavelength laser output power of 3.25 W with intensity ratio of 12 : 1 for ceramic are obtained. The results show that slight difference between fluorescence spectra results from the difference in laser spectrum between transparent ceramic and single crystal materials for multi-wavelength output. Thresholds of two different output couplers are both about 2 W. When the incident pump power increases to 13.5 W, a 1338 and 1356 nm dual-wavelength laser output power of 4.05 W and a 1356 and 1414 nm dual-wavelength laser output power of 3.65 W are achieved in Nd:YAG transparent ceramic. The corresponding slope efficiency values are 33.9% and 31.9%, respectively.

2.4 W highly efficient simultaneous dual-wavelength laser operation of monoclinic Yb(3+):Ca4LaO(BO3)3 crystals.

We have studied the simultaneous dual-wavelength laser operation of the X-cut, Y-cut, and Z-cut Yb(3+):Ca4LaO(BO3)3 crystals for the first time to the best of our knowledge. We analyzed the dual-wavelength laser output power and emission spectra under several output coupler transmittances. The stable dual-wavelength lasers were generated by adjusting the laser elements. A dual-wavelength laser output power 2.46 W was obtained with a slope efficiency of 67.5% by employing the Y-cut crystal at 1029 and 1036 nm. The two wavelengths had nearly the same relative intensity. The two different emission wavelengths were found to change with crystal direction and output coupler transmittance. This laser has a possible application as the laser source in the generation of different terahertz waves.

A study on the role of transmittances effect the self-Raman dual-wavelength laser output characteristics

In this work, the coupled equations of self-Raman dual-wavelength continuous-wave lasers are constructed by introducing the loss item of fundamental photon number. The output power analytical expressions of the fundamental laser and Raman laser are obtained through solving the couple equations. The impaction of transmittances on the self-Raman dual-wavelength laser output characteristics are simulated. Under different transmittance combination conditions, the changing rules of the separate output power, total output power and the ratio of two different wavelengths output power are given. The coupled equations are solved in approximations such as plane wave and independent-space intensity distribution, however the simulated results can show the main tendency of self-Raman dual-wavelength continuous-wave lasers, this has a certain guiding significance for the experiment.

Anisotropy of laser emission in monoclinic, disordered crystal Nd:LYSO

Multi-wavelength emissions have been demonstrated in many disordered laser crystals. Improving the emission controllability is crucial for their practical applications. However, it is difficult because the closely adjacent laser components cannot be effectively adjusted by the traditional resonator design. In this paper, the anisotropy of laser emission in a monoclinic, disordered crystal Nd:LuYSiO(5) (Nd:LYSO) is reported for the first time. By selecting crystal orientation, high power laser emission with different wavelengths and polarizations were obtained. For X-cut sample, 1076 nm single-wavelength laser output reached 7.56 W, which will be a useful light source for detecting carbonyl-hemoglobin and nitrite after frequency doubling. For Y- and Z-cut samples, 1076, 1079 nm dual-wavelength laser output reached 10.3 W and 7.61 W, with parallel and orthogonal polarizations, respectively, which are convenient to be used as the generation sources of 0.78 THz wave by type-I or type-II difference frequency. The output characteristic is well explained by a theoretical analysis on the stimulated emission cross-section. The present work reveals that the intrinsic anisotropy in disordered laser crystal can be utilized to elevate the emission controllability. Accordantly, the material's application scopes can be extended.

Single-frequency and dual-wavelength Ho:YAG nonplanar ring oscillator resonantly pumped by a Tm:YLF laser

A resonantly pumped monolithic Ho:YAG nonplanar ring oscillator (NPRO) with single-frequency and dual-wavelength laser outputs is demonstrated. The Ho:YAG NPRO is resonantly pumped by a 1907-nm Tm:YLF laser. In single-frequency operation, the output power is 3.09 W, with a slope efficiency of 61% and an optical efficiency of 48% with respect to the pump power. Up to 10 W dual-wavelength laser output at 2091 and 2097 nm is also obtained from the Ho:YAG NPRO with the maximum pump power, with a slope efficiency of 61% with respect to the pump power.

S + C + L Band tunable wavelength conversion using FWM dual-wavelength fiber laser in a highly nonlinear fiber

In this article, a novel wideband wavelength conversion is demonstrated using a highly nonlinear fiber consisting of a fluorine-doped fiber that has a high delta core and surrounded by a deeply depressed ring as opposed to the use of photonic crystal fibers.The wavelength conversion range is from 1460 to 1640 nm, which covers the S-, C- and L-bands of the optical network. The interacting waves consist of an arrayed waveguide grating tuned dual-wavelength fiber laser output together with a tunable laser source signal. A four-wave-mixing conversion of efficiency of −20 dB is achieved within a 70 nm tuning range within a 3.9 dB fluctuation. An optical signal to noise ratio of 30 dB is also realized within the same tuning range. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:379–382, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27284

Experimental Study on Dual Wavelength and Dual Pulse Q-Switched Frequency Doubling on a Tunable Cr:LiSAF Laser

A flashlamp-pumped Cr:LiSAF laser system with a voltage controlled Q-switch structure in the cavity is designed. A dual-wavelength and dual-pulse tunable laser output is gained. The relation of laser output behavior with input energy is studied experimentally. The output is dual-pulsed with the energy of the 32 mJ/pulse producing the total output energy of 64 mJ and the pulse width is about 27 ns at 850 nm. Then, we use one LBO crystal as the frequency doubling crystal to obtain a dual wavelength (448.1 nm and 449.15 nm) and dual pulse laser. The output for one wavelength is about 10.3 mJ and the line width is less than 0.02 nm.

Passively Q-switched dual-wavelength laser output of LD-end-pumped ceramic Nd:YAG laser

We reported a dual-wavelength laser with a ceramic Nd:YAG as laser material and Cr:YAG as frequency selector and saturable absorber. Continuous-wave output power was achieved to be as high as 6.19 W at 1052 nm. With Cr:YAG, the laser has dual-wavelength at 1052 and 1064 nm. The shortest pulse width, maximum pulse energy and highest peak power were 4.8 ns, 103.2 microJ, and 21.5 kW. This pulsed laser is possible to be used as a new source to generate terahertz radiation.