mW Of Pump Power Research Articles

Multiwavelength Er-doped fiber laser using an all-fiber Lyot filter.

We experimentally demonstrated a multiwavelength Er-doped fiber ring laser system by employing an all-fiber Lyot filter (AFLF) and a highly nonlinear fiber (HNLF). The AFLF was employed as a polarizing filter to generate a nonlinear polarization rotation effect and the highly dense and narrow bandwidth comb-like channels. A 1-km-long HNLF was used to enhance the nonlinearity of the laser cavity and suppress the mode competition for multiwavelength operation. In the experiment, 97 laser output channels within a 3dB bandwidth simultaneously were excited under 224mW pump power. The power fluctuation of lasing channels was less than 0.182dB, and the wavelength shift was less than 0.04nm in 100min, after treating the AFLF in a thermostatic ice bath. Meanwhile, the output laser was highly polarized with a degree of polarization up to 99.9%.

Wavelength-spacing-controllable multi-wavelength fiber laser based on a Lyot-Sagnac filter.

A wavelength-spacing-controllable multi-wavelength polarization-maintaining erbium-doped fiber laser (MW-PM-EDFL) in a linear cavity configuration is presented based on a Lyot-Sagnac filter and a nonlinear optical loop mirror (NOLM). Using a Lyot-Sagnac filter as the wavelength selective filter makes the wavelength spacing controllable by adjusting the effective length of polarization-maintained fiber (PMF) segments. An NOLM inducing wavelength-dependent cavity loss can be used as an amplitude equalizer, which is employed to suppress the mode competition resulting from the homogeneous line broadening effect of the erbium-doped fiber in the cavity. Thus, a stable wavelength-spacing-controllable MW-PM-EDFL is realized. In this experiment, 20 stable lasing wavelengths are obtained with a pump power of 170mW at 980nm when the length of the PMF is 13m. When the length of the PMF is 8m, 10 stable lasing wavelengths are obtained at 185mW pump power. The power fluctuations and wavelength shifts are less than 2dB and 0.02nm in 1h at room temperature. The demonstrated multi-wavelength fiber laser has great potential for applications in optical communications and optical sensing systems.

A tunable multi-wavelength Brillouin-erbium linear cavity fiber laser with higher optical signal to noise ratio

We experimentally demonstrated a widely tunable multi-wavelength Brillouin-erbium fiber laser by utilizing a double-pass pre-amplification Brillouin pump (BP) within a single-linear laser cavity. Owing to this pre-amplification technique, the laser can operate at low pump power and exhibit a low threshold operation of 35 mW pump power to create the first Stokes signal. By adjusting the polarization controller (PC), self-lasing cavity modes’ oscillation can be tuned over 10 nm from 1562 nm to 1572 nm. We experimentally showed that the proposed novel fiber laser structure can achieve up to ~33 output channels with a constant wavelength spacing of 0.088 nm at 7.4 dBm of BP power and 250 mW of the 980 nm pump power by varying the wavelength of the BP and adjusting the PC. In addition, an average of 32 stable output channels could all be tuned over 12 nm with an average optical signal to noise ratio of 25 dB.

Design Optimization of EDFA for 16 × 10 Gbps Data Rate DWDM System Using Different Pumping Configurations

In this paper, the erbium doped fiber amplifier (EDFA) is used as a booster and a pre amplifier in the dense wavelength division multiplexing system. We optimize the design parameters of the EDFA using the multi parameter optimization tools. The gain profile of the EDFA depend on the fiber length, Er3+ ion density, Er3+ doping radius at pump wavelength λp = 980 nm while the operating frequency range is 1546 nm to 1552 nm. The optimized EDFA length is found to be 8 m at 50 mW pump power which gives a maximum gain of 40 dB and 39.5 dB for co-pumping and bidirectional pumping respectively. The analysis to obtain the optimized parameters of the EDFA is done on the basis of gain, noise figure and the optical signal to noise ratio varying the input power of 0 dBm–30 dBm.

Q‐switched and mode‐locked ytterbium‐doped fibre lasers with Sb 2 Te 3 topological insulator saturable absorber

Q-switched and mode-locked fibre lasers have been successfully demonstrated in ytterbium-doped fibre laser cavity by taking an advantage of the optical absorption of antimony telluride (Sb2Te3) material. The Sb2Te3 was embedded into polyvinyl alcohol to function as a saturable absorber (SA). A Q-switching pulses train was obtained by incorporating the SA into the laser ring cavity configured with 3 dB coupler. The Q-switching pulse repetition rate increases from 24.4 to 55 kHz as the pump power is increased from the threshold of 75.4–96.2 mW. The maximum pulse energy of 252.6 nJ is obtained at 82.3 mW pump power. On the other hand, by changing the output coupler to 10 dB coupler, a stable self-started mode-locking operation was then generated at pump power range from 47.8 to 89.4 mW with a fixed repetition rate of 24.2 MHz. At 89.4 mW pump power, the maximum output power and pulse energy are obtained to be around 18.6 mW and 0.8 nJ, respectively. The authors results display that the Sb2Te3 material could also be developed as an effective SA for both Q-switched and mode-locked fibre lasers.

Dual-wavelength single-longitudinal-mode erbium-doped fiber laser with Mach–Zehnder interferometer and saturable absorber loop

A stable dual-wavelength erbium-doped fiber laser (DW-EDFL) in the single longitudinal mode (SLM) with a Mach–Zehnder interferometer (MZI) and a saturable absorber loop (SAL) is proposed and demonstrated experimentally. Dual wavelengths are obtained with different MZI arm lengths. After the first mode selection of the tunable fiber Bragg grating, SLM operation of the dual-wavelength is acquired by the SAL based on the Vernier effect and spatial hole burning, which induce an auto-tracking narrow bandwidth filter with an optical coupler and a 2 m unpumped erbium-doped fiber (EDF). The output of the DW-EDFL shows good performance, achieving 1.08 kHz at dual wavelengths of 1558.67 nm and 1558.77 nm. The interval of the dual wavelength is 0.1 nm, which has a good agreement with the theoretical value, and the peak powers are −5.508 dBm and −5.993 dBm, respectively under 170 mW pump power. Meanwhile, because of the automatic tracking of the wavelength of the SAL, the optical power instability and beating frequency fluctuation of the dual wavelength are less than 0.5 dB and 0.5 MHz, respectively, showing favorable stability.

Passively mode-locked ultrashort pulse fiber laser incorporating multi-layered graphene nanoplatelets saturable absorber

In this paper, a passive mode-locked erbium-doped fiber laser (EDFL) incorporating graphene nanoplatelet (GNP) powder-based saturable absorber (SA) with short pulse duration in femtosecond range is demonstrated. A good synthesis of GNP can be simply produced via a combination of thermal, chemical, and mechanical exfoliation of expandable graphite. The GNP-SA is fabricated by mechanically imprinting the powder onto the tip of a single mode fiber ferrule. The characterization of SA is done via focus ion beam scanning electron microscope, energy dispersive X-ray spectroscopy, as well as Raman spectroscopy. The fabricated GNP-SA has 1.8 % modulation depth and C-band transmission loss of less than 1.8 dB. The ring-configuration EDFL integrated with GNP-SA yields a mode-locking threshold of 22.6 mW pump power. Net anomalous dispersion of the laser cavity is validated by the observation of Kelly’s sideband in the optical spectrum. At maximum pump power of 115.8 mW, the mode-locked EDFL has a pulse repetition rate of 13.11 MHz, sech2 profile fitted pulse duration of 694 fs, peak-to-pedestal extinction ratio of 58.2 dB, average output power of 6.7 mW, and pulse energy of 507.2 pJ. Our proposed GNP-SA is feasible as a mode-locker for ultrashort pulsed fiber laser with advantage in terms of simple synthesis and fabrication technique.

Noise-like pulses generated from a passively mode-locked fiber laser with a WS2 saturable absorber on microfiber

We report on a noise-like pulse (NLP) generation in a mode-locked erbium-doped all-fiber laser using a WS2-deposited microfiber saturable absorber (SA). The prepared WS2 SA can serve as an excellent mode-locked and highly nonlinear device in the all-fiber laser cavity. At proper pump power and polarization states, typical NLPs can be generated. Adjusting the polarization also yields special NLPs with second-order harmonic mode-locking. For typical NLPs, 37 mW maximum output power and 8.8 nJ pulse energy are achieved at 334 mW pump power. The microfiber-based WS2 component could be a potential device for exploring nonlinear dynamics, such as NLPs.

Nickel oxide film saturable absorber for mode-locking operation at 1.55-micron region

The generation of mode-locking pulse train in Erbium-doped fiber laser (EDFL) cavity was demonstrated using Nickel Oxide (NiO) saturable absorber (SA). The NiO compound synthesized via sonochemical method was embedded into poly ethylene oxide (PEO) film through solution casting technique to fabricate the SA film device. A small piece of the SA film was sandwiched between two ferrules in the EDFL cavity. By adding 180[Formula: see text]m single mode fiber (SMF) in the ring cavity, a stable mode-locking pulse train operating at 1558[Formula: see text]nm with a repetition rate of 1.1[Formula: see text]MHz was achieved. At 197.5[Formula: see text]mW pump power, the proposed mode-locked EDFL has output power and pulse energy of 3.35[Formula: see text]mW and 3.36[Formula: see text]nJ, respectively. This study may well be the first demonstration of mode-locked EDFL using NiO-based SA. The result indicates that NiO is the promising material for ultrafast photonic applications.

Analysis of temperature based power spectrum in EDFA and YDFA with different pump power for THz applications

Abstract The indispensible output power spectrum for optical amplifier system in the presence of temperature using EDFA and YDFA is numerically investigated. The notion of temperature suggested as −30 °C, 30 °C, 60 °C, 90 °C. Each output spectrum has been analyzed at −30 °C, 30 °C, 60 °C, 90 °C in both EDFA and YDFA systems. The output power at the point of two maxima as 26.829 dBm and 23.260 dBm at wavelengths 1530 nm and 1550 nm for EDFA, maximum output power as −6.499 dBm at wavelength 1043 nm for YDFA system are examined keeping 900 mw pump power and 60 °C temperature. Similarly, the maximum output power is analyzed as −6.499 dBm at the wavelength of 1043 nm for the same pump power and temperature in YDFA system. Also the results have been plotted for various pump power and temperature.

Low-loss Ga:Er:LiTaO3 optical waveguide for integrated optics

Low-loss gallium(Ga3+)-diffused erbium(Er3+)-doped LiTaO3(Ga:Er:LiTaO3) channel waveguide was fabricated using erbium metal film diffusion followed by photolithographically patterned gallium oxide(Ga2O3) strip diffusion. Secondary ion mass spectrometry analysis shows that Er3+ concentration follows a Gaussian profile, Ga3+ concentration follows a sum of two error functions at the waveguide surface and a Gaussian profile in the depth direction. Optical studies show that the waveguide supports single-mode propagation at 1.5 μm wavelength with a coupling loss <1 dB and a waveguide loss 0.2(0.3) dB/cm for the TE(TM) mode, and with a small polarization dependence in mode field distribution. Stable optical gain of ∼1.0 dB/cm was measured at 1547 nm wavelength with 220 mW pump power of 980 nm wavelength, indicating good photorefractive damage resistance of the waveguide.

Centimeter-scale Yb-free heavily Er-doped silica fiber laser.

The laser behavior of a centimeter-scale Er3+/Al3+ codoped silica fiber with core numerical aperture and core diameter of 0.15 and 8μm, respectively, is reported. The core glass was prepared by the sol-gel method combined with high-temperature sintering; it contained Er3+ ion concentration as high as 1.32×1020 ions/cm3 and an Al/Er mole ratio of 10. The high doping homogeneity of Er3+ ions in the fiber core was confirmed by an electron probe microanalyzer element scanning, long Er3+: I13/24 emission lifetime of 11.4ms, and low refractive index fluctuation of fiber core (±1×10-4). The signal gain of fibers with 4.6cm, 10cm, and 16cm lengths was tested in the 1500-1620nm range. A gain of 7dB is achieved at 1560nm in a 16-cm-long EDF under 230mW pump power. Aimed for CO2 sensor application, the laser behavior of Er/Al codoped fiber was tested at 1572nm. A slope efficiency of 12% and an output power of 15mW were achieved in a 10-cm-long fiber under 166mW absorbed pump power. The newly developed silica fiber is promising for use in high-repetition-rate lasers.

Dual-wavelength, mode-locked erbium-doped fiber laser employing a graphene/polymethyl-methacrylate saturable absorber.

Mode-locked fiber laser incorporating a saturable absorber is an attractive configuration due to its stability and simple structure. In this work, we demonstrate a dual-wavelength passively mode-locked erbium-doped fiber laser employing a graphene/polymethyl-methacrylate saturable absorber. A laser resonator is developed based on dual cavity architecture with unidirectional signal oscillation, which is connected by a fiber branch sharing a common gain medium and saturable absorber. Dual wavelength mode-locked fiber lasers are observed at approximately 1530 and 1560 nm with 22.6 mW pump power threshold. Soliton pulse circulates in the laser cavity with pulse duration of 900 and 940 fs at shorter and longer wavelengths, respectively. This work presents a viable option in developing a low threshold mode-locked laser source with closely spaced dual wavelength femtosecond pulses in the C-band wavelength region.

Stable passively Q-switched erbium-doped fiber laser incorporating a PbS quantum dots polystyrene composite film based saturable absorber

We demonstrated a passively Q-switched erbium-doped fiber laser (EDFL) using PbS quantum dots in polystyrene films (QDPFs) as saturable absorbers (SAs). Compared to other SAs, PbS QDPFs have advantages of broad absorption range, high quantum yield, low cost, and facile preparation. We have successfully generated stable Q-switched pulses with an average output power of 40.19mW, a single pulse energy of 586.1nJ, a repetition rate of 68.04kHz, a pulse width of 3.9μs, and a signal-to-noise ratio of 50.5dB under 660mW pump power. The output of the EDFL has been monitored for 5 consecutive hours under laboratory conditions to show stable operation of the laser system.

Molybdenum disulfide saturable absorber for eye-safe mode-locked fiber laser generation

We demonstrated an all-fiber mode-locked Thulium–Holmium co-doped fiber laser (THDFL) based on molybdenum disulfide (MoS2) tape saturable absorber. The THDFL generates a mode-locked pulse in anomalous regime at 1,979[Formula: see text]nm using 5[Formula: see text]m long Thulium–Holmium co-doped (THDF) as a gain medium. Through mechanical exfoliation method, the MoS2 was mechanically extracted from a commercial MoS2 crystal by using a clear scotch tape. Through balanced twin-detector measurement, the obtained MoS2 tape has a nonlinear absorption of 10% with 100[Formula: see text]MW/cm2 saturation intensity. Under 775[Formula: see text]mW to 852[Formula: see text]mW pump power, a stable pulse train was obtained at 9.12[Formula: see text]MHz repetition rate with a signal-to-noise ratio (SNR) of 45[Formula: see text]dB. The maximum output power and pulse energy were measured about 20[Formula: see text]mW and 2.2[Formula: see text]nJ, respectively. With a 3-dB spectral bandwidth of 2.1[Formula: see text]nm, the minimum possible pulse width was determined as 1.97[Formula: see text]ps.

Multi-Wavelength Q-Switched Ytterbium-Doped Fiber Laser with Multi-Walled Carbon Nanotubes

ABSTRACTWe demonstrate a passively multi-wavelength Q-switched Ytterbium-doped fiber laser (YDFL) based on a multi-wall carbon nanotubes embedded in polyethylene oxide film as saturable absorber. The YDFL generates a stable multi-wavelength with spacing of 1.9 nm as the 980 nm pump power is fixed within 62. 4 mW and 78.0 mW. The repetition rate of the laser is tunable from 10.41 to 29.04 kHz by increasing the pump power from the threshold power of 62.4 mW to 78 mW. At 78 mW pump power, the maximum pulse energy of 38 nJ and the shortest pulse width of 8.87 µs are obtained.

Low threshold L-band mode-locked ultrafast fiber laser assisted by microfiber-based carbon nanotube saturable absorber

We demonstrate a passively mode-locked erbium-doped fiber laser in L-band wavelength region with low mode-locking threshold employing a 1425 nm pump wavelength. The mode-locking regime is generated by microfiber-based saturable absorber using carbon nanotube-polymer composite in a ring cavity. This carbon nanotube saturable absorber shows saturation intensity of 9 MW/cm2. In this work, mode-locking laser threshold is observed at 36.4 mW pump power. At the maximum pump power of 107.6 mW, we obtain pulse duration at full-width half-maximum point of 490 fs and time bandwidth product of 0.33, which corresponds to 3-dB spectral bandwidth of 5.8 nm. The pulse repetition rate remains constant throughout the experiment at 5.8 MHz due to fixed cavity length of 35.5 m. Average output power and pulse energy of 10.8 mW and 1.92 nJ are attained respectively through a 30% laser output extracted from the mode-locked cavity. This work highlights the feasibility of attaining a low threshold mode-locked laser source to be employed as seed laser in L-band wavelength region.

Passively harmonic mode-locked erbium-doped fiber laser at a 580 MHz repetition rate based on carbon nanotubes film

We propose and demonstrate a passively harmonic mode-locked erbium-doped fiber laser (EDFL) using carbon nanotubes polyvinyl alcohol (CNTs-PVA) film. The laser allows generation of the pulses with a repetition rate of 580 MHz, which corresponds to the 22nd harmonics of a 26.3 MHz fundamental repetition rate under 323 mW pump power. A particularly noteworthy feature of the pulses is the super-mode suppression ratio (SMSR), which is over 40 dB, indicating a stable operation.

Mode‐locked femtosecond 910 nm Nd:fibre laser with phase biased non‐linear loop mirror

The authors demonstrate a mode-locked Nd:fibre laser working at 910 nm incorporating a phase biased non-linear loop mirror. The broadest spectral width of the pulse is 11.9 nm and the output power is 20 mW with 450 mW pump power. The dechirped pulse width is 206 fs. To the best of authors' knowledge, this is the first demonstration of a 900 nm femtosecond neodymium fibre laser based on a non-linear loop mirror.

Graphene Oxide Film as Passive Q-switcher in Erbium-doped Fiber Laser Cavity

All-fiber passively Q-switched fiber lasers have been demonstrated by using graphene oxide (GO) Q-switcher for possible applications in telecommunication, laser processing, fiber sensing and medical community. The GO material was obtained through a modified Hummers method from expanded acid washed graphite flakes and it was embedded into a polyvinyl alcohol (PVA) film to form a saturable absorber (SA) device. The Q-switched pulse operates at 1563.3 nm with a repetition rate that can be tuned from 44.33 kHz to 61.77 kHz as the pump power changes from 39 mW to 96 mW. The highest repetition rate of 61.77 kHz is achieved at a pump power of 96 mW and it is observed that the Q-switched pulse produced maximum pulse energy of 0.054 nJ and pulse width of 5.57 ?s at 96 mW pump power. Full Text: PDF ReferencesJ. Zayhowski and C. Dill, "Coupled-cavity electro-optically Q-switched Nd:YVO4 microchip lasers", Optics letters 20, 716 (1995). CrossRef C.-x. Gao, W. Zhao, Y.-s. Wang, S.-l. Zhu, G.-f. Chen, and Y.-g. Wang, "Passive Q-switched fiber laser with SESAM in ytterbium-doped double-clad fiber", 27th International congress on High-Speed Photography and Photonics, 62794G (2007). CrossRef M. Ahmed, N. Ali, Z. Salleh, A. Rahman, S. Harun, M. Manaf, "Q-switched erbium doped fiber laser based on single and multiple walled carbon nanotubes embedded in polyethylene oxide film as saturable absorber", Optics &amp; Laser Technology 65, 25 (2015). CrossRef S. Harun, M. Ismail, F. Ahmad, M. Ismail, R. Nor, N. Zulkepely, et al., "A Q-switched erbium-doped fiber laser with a carbon nanotube based saturable absorber", Chinese Physics Letters 29, 114202 (2012). CrossRef A. Martinez and Z. Sun, "Nanotube and graphene saturable absorbers for fibre lasers", Nat Photon 7, 842 (2013). CrossRef J. Boguslawski, J. Sotor, G. Sobon, R. Kozinski, K. Librant, M. Aksienionek, et al., "Graphene oxide paper as a saturable absorber for Er- and Tm-doped fiber lasers", Photonics Research 3, 119 (2015). CrossRef H. Ahmad, F. D. Muhammad, M. Z. Zulkifli, and S. W. Harun, "Q-switched pulse generation from an all-f iber distributed Bragg reflector laser using graphene as saturable absorber", Chinese Optics Letters 11, 071401 (2013). CrossRef