Switchable Dual Wavelength Research Articles

Switchable Dual-Wavelength Fiber Laser with Narrow-Linewidth Output Based on Parity-Time Symmetry System and the Cascaded FBG

In this paper, a dual-wavelength narrow-linewidth fiber laser based on parity-time (PT) symmetry theory is proposed and experimentally demonstrated. The PT-symmetric filter system consists of two optical couplers (OCs), four polarization controllers (PCs), a polarization beam splitter (PBS), and cascaded fiber Bragg gratings (FBGs), enabling stable switchable dual-wavelength output and single longitudinal-mode (SLM) operation. The realization of single-frequency oscillation requires precise tuning of the PCs to match gain, loss, and coupling coefficients to ensure that the PT-broken phase occurs. During single-wavelength operation at 1548.71 nm (λ1) over a 60-min period, power and wavelength fluctuations were observed to be 0.94 dB and 0.01 nm, respectively, while for the other wavelength at 1550.91 nm (λ2), fluctuations were measured at 0.76 dB and 0.01 nm. The linewidths of each wavelength were 1.01 kHz and 0.89 kHz, with a relative intensity noise (RIN) lower than −117 dB/Hz. Under dual-wavelength operation, the maximum wavelength fluctuations for λ1 and λ2 were 0.03 nm and 0.01 nm, respectively, with maximum power fluctuations of 3.23 dB and 2.38 dB. The SLM laser source is suitable for applications in long-distance fiber-optic sensing and coherent LiDAR detection.

Switchable dual-wavelength Q-switched fiber laser based on sputtered indium tin oxide as saturable absorber

This paper demonstrate experimentally the generation of a stable switchable dual-wavelength Q-switched fiber laser. The pulsed fiber lasers is generated from deposited Indium Tin Oxide (ITO) saturable absorber (SA) on fiber ferrule, which is prepared by using DC Magnetron Sputtering. The deposited ITO SA is then being sandwiched in between the two fiber ferrules. A stable switchable dual-wavelength is generated by the aid of two cascaded fiber Bragg gratings (FBGs). To achieve a flexible switched in individual wavelength of 1532 or 1533 nm and simultaneously dual-wavelength fiber laser, the in line polarization controller is utilized to control the mode competition in the fiber laser cavity. The proposed fiber laser is capable of generating output at the pump power of 118.10 mW, centered at wavelength 1532 nm. The proposed design is having a repetition rate of 48.30 kHz and a pulse width of 5.22 µs. Similarly, at 1533 nm, it generates a repetition rate of 25.61 kHz and a pulse width of 7.72 µs. The output is also observed to remain unchanged over time, indicating high stability with the signal to noise ratio of 52.70 dB and 52.00 dB at wavelength 1532 nm and 1533 nm, respectively. The combination between ITO and cascaded FBG can offer a feasible and straightforward candidate for a multiwavelength fiber laser according to these results. Laser radar and terahertz generation may become a few of the potential fields that related to this work.

Compact L-band switchable dual wavelength SOA based on linear cavity fiber laser

A semiconductor optical amplifier (SOA) based linear cavity L-band dual wavelength fiber laser (DWFL) with a switchable output is proposed and its operation demonstrated. The DWFL is configured as a linear cavity, with a 1 × 24 arrayed waveguide grating together with two optical switches providing channel spacing tunability. An L-band SOA, with a central operating wavelength of 1580 nm and an operation bandwidth of 1500–1640 nm serves as the gain medium of the proposed laser cavity. The DWFL is able to generate a dual-wavelength output, with the widest spacing obtained being 18.7 nm and the narrowest spacing being 0.8 nm. The generated output is highly stable, with only minor power fluctuations of less than 2 dB as well as having a signal-to-noise ratio of 42 dB. The proposed setup would have numerous uses, particularly for sensor applications.

Dual-wavelength passively Q-switched Erbium-doped fiber laser with MWCNTs slurry as saturable absorber

In this work, a compact, stable dual-wavelength Q-switched laser with a multi-walled carbon nanotubes (MWCNTs) slurry as saturable absorber (SA) which is independent of any host polymer has been demonstrated. The MWCNTs slurry is fabricated and the peak shift is investigated using Raman spectroscopy.The passively Q-switched erbium-doped fiber laser (EDFL) oscillated simultaneously at 1532.32 nm and 1556.97 nm with 24.67 nm peak separation, at threshold and maximum input power of 26mW and 74mW respectively.By increasing the input pump power from 36 mW to 74 mW, the pulse train repetition rate increases from 25 kHz to 78 kHz, while the pulse width is reduced from 17.84 us to 5.24 ?s. The generated pulse produced maximum pulse energy and maximum peak power of 11.97 nJ and 2.05 mW, respectively at maximum input pump power. The recorded signal to noise ratio is about 62 dB and shows that the proposed MWCNTs slurry based SAis able to generate dual wavelength Q-switched pulse laser with high stability pulse. Full Text: PDF ReferencesL.Liu, Z. Zheng, X. Zhao,S. Sun, Y. Bian, Y. Su, J. Liu, and J. Zhu, "Dual-wavelength passively Q-switched Erbium doped fiber laser based on an SWNT saturable absorber", Optics Communications 294, 267 (2013). CrossRef Z. Luo, M. Zhou, J. Weng, G. Huang, H. Xu, C. Ye, and Z. Cai, "Graphene-based passively Q-switched dual-wavelength erbium-doped fiber laser", Optics Letters 35, 3709 (2010). CrossRef F. Lou, R. Zhao, J. He, Z. Jia, X. Su, Z. Wang, J. Hou, and B. Zhang, "Nanosecond-pulsed, dual-wavelength, passively Q-switched ytterbium-doped bulk laser based on few-layer MoS2 saturable absorber", Photon. Res. 3, A25 (2015). CrossRef F. A. A. Rashid et al., "Using a black phosphorus saturable absorber to generate dual wavelengths in a Q-switched ytterbium-doped fiber laser", Laser Phys. Lett. 13, 1 (2016). CrossRef J. Sotor, G. Sobon, I. Pasternak, K. Krzempek, G. Dudzik, A. Krajewska, W. Strupinski, and K. M. Abramski, "Dual-wavelength fiber mode-locked laser based on graphene saturable absorber", Proc. of SPIE 8961, 89612A (2014). CrossRef S. Alwarappan, and A. Kumar, Graphene-Based Nanomaterials (Boca Rota, CRC Press 2014).N. Taib, N. Bidin, H. Haris, N. N. Adnan, M. Ahmad, and S. W. Harun, "Multi-walled carbon nanotubes saturable absorber in Q-switching flashlamp pumped Nd:YAG laser", Optics & Laser Technology 79, 193 (2016). CrossRef M. Ahmad, A. Latiff, Z. Zakaria, and S. Harun, "Q-Switched Ultrafast TDFL Using MWCNTs-SA at 2 ?m Region", International Journal of Computer and Communication Engneering 3, 446 (2014). CrossRef H. Ahmad, K. Z. Hamdan, F. D. Muhammad, S. W. Harun, and M. Z. Zulkifli, "Switchable dual-wavelength CNT-based Q-switched using arrayed waveguide gratings (AWG)", Applied Physics B 118, 269 (2015). CrossRef J. M. Dudley and J. R. Taylor, Supercontinuum Generation in Optical Fibres (New York, Cambridge University Press 2010). CrossRef H. Ahmad, M. A. M. Salim, M. R. K. Soltanian, S. R. Azzuhri, and S. W. Harun, "Passively dual-wavelength Q-switched ytterbium doped fiber laser using Selenium Bismuth as saturable absorber", Journal of Modern Optics 62, 1550 (2015). CrossRef H. Chu et al., "Dual-Wavelength Passively Q-Switched Nd,Mg:LiTaO3 Laser With a Monolayer Graphene as Saturable Absorber", IEEE Journal of Selected Topics in Quantum Electronics 21, 1600705 (2015). CrossRef Z. T. Wang, Y. Chen, C. J. Zhao, H. Zhang, and S. C. Wen, "Switchable Dual-Wavelength Synchronously Q-Switched Erbium-Doped Fiber Laser Based on Graphene Saturable Absorber", IEEE Photonics Journal 4, 869 (2012). CrossRef J. H. Liu et al., "Passively Q-switched dual-wavelength Yb:LSO laser based on tungsten disulphide saturable absorber", Chin. Phys. B 25, 034207 (2016). CrossRef Z. C. Tiu et al, "Multi-wavelength Q-switched Erbium-doped fiber laser with photonic crystal fiber and multi-walled carbon nanotubes", Journal of Modern Optics 61, 1133 (2014). CrossRef

High Power Switchable Dual-Wavelength Linear Polarized Yb-Dozped Fiber Laser around 1120 nm

A single-and dual-wavelength switchable polarized Yb-doped double-clad fiber laser around 1120 nm based on a pair of fiber Bragg gratings (FBGs) is demonstrated. The polarization-maintaining (PM) linear cavity is composed of a double clad PM Yb-doped fiber (YDF) and a pair of PM FBGs. The laser can operate in stable dual-wavelength or wavelength-switching modes due to the polarization hole burning (PHB) and the spatial hole burning (SHB) enhanced by the PM linear cavity. In dual-wavelength operation, the two orthogonally polarized wavelengths are centered at 1118.912 nm and 1119.152 nm, with an interval of 0.24 nm and a signal to noise ratio (SNR) of 35 dB. The maximum output power is 14.67 W when the launched LD pump is 24 W corresponding to an optical efficiency of 61.1%. The lasing lines switchover may be realized by adjusting the polarization controller (PC) fitted in the cavity. The two single-wavelengths are 1118.912 nm and 1119.152 nm. When the injected LD pump is 24 W, the highest output powers are 7.68 W and 8.64 W corresponding to optical efficiencies of 32% and 36% respectively. The spectral linewidth of the lasing lines are 0.075 nm and 0.07 nm, and the average numerical values of PER aredB and 19.9 dB, respectively.

Single Polarization, Dual Wavelength Fiber Laser Based on a 3-Stage All Fiber Lyot Filter

We have demonstrated a switchable dual wavelength fiber ring laser with a high degree of polarization output by using an intracavity 3-stage all fiber Lyot filter. The filter is formed by concatenating four 45° tilted fiber gratings separated by polarization maintaining fibers with a length ratio of 1:2:4 (20, 40, and 80 cm), giving a compact integrated configuration with reduced bandwidth. Switchable dual wavelength or single wavelength output at 1533.5 and 1563.3 nm has been achieved. The output lasing is considerably stable owing to the in-phase mode-selecting function of the multistage Lyot filter, and has a very high degree of polarization higher than 99.9%.

Switchable Dual-Wavelength Synchronously Q-Switched Erbium-Doped Fiber Laser Based on Graphene Saturable Absorber

We demonstrate a switchable dual-wavelength synchronously pulsed fiber laser Q-switched by graphene saturable absorber. Wavelength-resolved studies on the output Q-switched pulses show that despite of large wavelength spacing up to 26 nm, the two Q-switched pulses at each individual wavelength can be temporally synchronized with per-pulse energy up to ~ 70 nJ. Further experiments show that by adjusting the intracavity birefringence, dual-wavelength emission can be switched to another dual-wavelength operation regime with wavelength separation of 5.7 nm. Our experimental results are also qualitatively supported by the cavity linear transmission characteristics of the ring cavity.

Experimental observation of lasering behavior in wavelength-switchable fiber laser with arrayed waveguide grating

A simple and wavelength-switchable fiber laser consisting mainly of an Erbium-doped fiber amplifier (EDFA) which provides the optical gain and an 1×40 (1 input channel to 40 output channels) arrayed waveguide grating (AWG) that supports wavelength selection is reported. The lasering behavior in wavelength-switchable fiber laser is investigated experimentally. One can obtain wavelength-switchable single-longitudinal-mode (SLM) single wavelength laser with different wavelength by changing different channel of the AWG as the wavelength selection element. Lasering wavelength hopping in dual wavelength laser operation for low pump power is experimentally observed. The wavelength hopping and the output power of the laser is controlled by using a variable optical attenuator (VOA). The wavelength hopping operation is eliminated for high pump power. One can obtain switchable dual wavelength laser with different wavelength by selecting different two channels of the AWG. The output laser exhibits a good performance having a high sidemode suppression ratio (SMSR), narrow line-width and symmetrical spectrum.

Switchable Dual-Wavelength and Passively Mode-Locked All-Normal-Dispersion Yb-Doped Fiber Lasers

A switchable dual-wavelength and passively mode- locked ytterbium-doped fiber laser (YDFL) in the all-normal-dispersion (ANDi) regime is reported and demonstrated for the first time. Using a phase-shifted long-period fiber grating (PS-LPFG) as an all-fiber format spectral filter in the laser cavity, a stable and switchable dual-wavelength mode-locked operation is achieved by nonlinear polarization evolution (NPE). The maximum output energy of the dual-wavelength pulse is 25.76 nJ at a repetition rate of 2.499 MHz. It opens a new possibility to achieve switchable multiwavelength and mode-locked laser output in the ANDi cavity in an all-fiber format.

Flat and compact switchable dual wavelength output at 1060 nm from ytterbium doped fiber laser with an AWG as a wavelength selector

A dual-wavelength ytterbium doped fiber laser with a narrowest spacing of 0.53 nm and widest spacing of 12.2 nm at 1064 nm is presented in this paper. An arrayed waveguide grating (AWG) together with an optical channel selector (OCS) have also been incorporated in the proposed setup that works as a switchable mechanism giving 23 different wavelength tunings. Producing an average output power of −8 dB m and side mode suppression ratio (SMSR) of 59.65 dB, this dual-wavelength fiber laser is quite stable with an output power variance as low as 0.47 dB giving it an advantage due to its switching ability and stable dual-wavelength output powers.

All-FBG-Based Switchable Dual Wavelength Erbium-Doped Fiber Laser with High Wavelength Tunability

All-FBG-Based Switchable Dual Wavelength Erbium-Doped Fiber Laser with High Wavelength Tunability

Single-polarization, switchable dual-wavelength erbium-doped fiber laser with two polarization-maintaining fiber Bragg gratings

An improved erbium-doped fiber laser configuration for achieving single-polarization, switchable dual-wavelength of orthogonal polarizations oscillations at room temperature is proposed. For the first time, two fiber Bragg gratings (FBGs) directly written in a polarization-maintaining (PM) and photosensitive erbium-doped fiber (PMPEDF) as the wavelength-selective component are used in a linear laser cavity. Due to the polarization hole burning (PHB) enhanced by the polarization-maintaining FBG (PMFBG), the laser can be designed to operate in stable dual-wavelength or wavelength-switching modes with a wavelength spacing of 0.336 nm at room temperature by adjusting a polarization controller (PC). Each lasing line shows a single polarization with a polarization extinction ratio of >25 dB under different pump levels. The optical signal-to-noise ratio (OSNR) is greater than 50 dB. The amplitude variation with 16 times scans in nearly one and half an hour is less than 0.5 dB at both operating wavelength.

Switchable dual wavelength erbium‐doped fiber laser at room temperature

AbstractA simple technique of a switchable dual wavelength erbium‐doped fiber laser based on fiber Bragg gratings is proposed and demonstrated by using both the linear cavity loss controlling and the homogeneous gain broadening of EDF. The single or dual lasing wavelength can be also obtained by controlling of two linear cavity losses at room temperature. The stability response time for the small‐amplitude stability of less than 1% is measured to be less than 0.27 ms. High‐quality EDF laser output with a high extinction ratio of more than ∼40 dB is achieved for all wavelength switching cases. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1433–1435, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22421

Tuneable and switchable dual wavelength lasers using optical fibre Bragg grating external cavities

Two novel external cavity lasers are demonstrated experimentally. The first utilises a Bragg grating fabricated in highly birefringent optical fibre and offers the ability to switch between modes that are separated in polarisation and wavelength. The second utilises two spatially separate Bragg gratings fabricated in mono-mode fibre. Both can be used for tunable beat frequency generation.