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In this work, a supercontinuum (SC) source is proposed and demonstrated using a highly-doped, 2 m long zirconia-erbium doped fiber (Zr-EDF) with a dopant concentration of 3800 ppm/wt and a narrow core 100 m long single-mode-fiber (SMF). A graphene based saturable absorber (SA) is used as a passive mode-locker, generating pulses with an average output power, pulse energy and peak power of ∼0.9 mW, ∼69.8 pJ and ∼83 W respectively and a repetition rate of 12.9 MHz. This is then amplified using a 140 mW amplifier, giving an output power, pulse energy and peak power of ∼75.0 mW, 5.8 nJ and ∼6.76 kW respectively and injected into a 100 m long SMF, to generate an SC output which spans from 1450 to more than 1700 nm, with a pulse width at its full-width-at-half-maximum (FWHM) of 120 fs, 7 times lower than the 840 fs FWHM width of the pulses from the fiber laser. The narrow core SMF performs comparably to longer lengths of standard SMF-28 fibers.

A tunable spacing dual-wavelength Q-switched fiber laser is experimentally demonstrated based on a fiber Bragg grating tunable device incorporated in an erbium-doped fiber laser (EDFL). The system utilizes two identical fiber Bragg gratings (FBGs) at 1547.1 nm origin to enable two laser lines operation. The wavelength separations between two laser lines are controlled by fixing one of the FBGs while applying mechanical stretch and compression to the other one, using a fiber Bragg grating tunable device. The seven steps of wavelength spacing could be tuned from 0.3344 to 0.0469 nm spacing. Pulse characteristics for both close and wide spacing of dual-wavelength Q-switched fiber laser are successfully being recorded. The findings demonstrate the latest idea of dual-wavelength fiber laser based on FBG tunable device, which offers a wide range of future applications.

This report makes a comparison between the spectrum features of plasmonic metamaterial metal-insulator-conductor (MIC) sensor with a monolayer of graphene and another MIC sensor with a multilayer of graphite as the back reflector. In both structures, the silicon substrate as an insulator layer was sandwiched between subwavelength periodic nanogold cones as the first layer and graphene and graphite as the third layer, respectively. Nanolayer of chromium nanorods was also considered in the structure of MIC sensors as an interface layer between silicon and nanogold cone metasurface. The performance of the sensor was evaluated under different incident polarized light angles and different thickness of the metasurface when the metasurface infiltrated with seawater and air. The transmission spectrum of monolayer graphene-based MIC sensor, respecting to s-polarized waves, reveals prominent feature to detect the air rather than seawater in invisible regime. Meanwhile, the reflection spectrum of graphite-based MIC sensor provides ∼0 % reflection under resonance condition regarding s- and p-polarized waves for detecting air in visible spectrum.

Generation of dual-wavelength using passive semiconductor microring resonator with two sections of apodized grating with total length of 26 µm on the right and left sides is presented here. In this research we use the timedomain travelling wave (TDTW) method to model and simulate the microring resonator made of InGaAsP/InP waveguide. Microring resonator based optical mirrors and band-limited reflectors have been the subject of intense investigations in recent years. Therefore, we propose the microring resonator made of InGaAsP/InP waveguide having two sides grating section. The grating sections have a trapezoidal profile. The gratings provide the means to suppress repetition of the reflection spectrum at every free spectral range (FSR) removed from the design wavelength. The total grating length is 26 µm (each grating side has length of 13 µm), where the total circumference of the microring resonator is 526 µm. Propagation of the input Gaussian pulse (with 10 mW power and bandwidth of 0.76 ps) within the grating sections is presented, where it shows a good confinement of the propagation within the waveguide. As a result, multiple dual-wavelengths with tunable spacing within a range of 127 pm (15.8 GHz) and 237 pm (29.6 GHz) could be generated at the throughput port of the microring resonator. The dispersion of the grating section versus the total grating length and the frequency response of the throughput port output signals are presented. The generated dual-wavelength has many applications in optical sensing, radio frequency (RF) radiation, optical communication, optical switching, millimetre wave generators and biological research.

A compact and tunable fiber laser is demonstrated using a microfiber knot resonator structure made by a highly doped Erbium fiber. A stable laser output is achieved at the 1533-nm region with a signal to noise ratio of 15 dB using a 63-mW 980-nm pump power. With the assistance of a copper wire touching the circumference of the ring, operating wavelength of the proposed laser can be tuned by injecting electric current into the copper wire. The peak wavelength of the laser can be tuned from 1533.3 to 1533.9 nm as the loading current is increased from 0 to 1.0 A. This is due to the thermally induced optical phase shift attributable to the heat produced by the flow of the current. It is also shown experimentally that the wavelength shift is linearly proportional to the square of the amount of current with a tuning slope of 700 pm/A2.

A tunable laser is demonstrated using a microfiber knot resonator structure made by erbiumdoped fiber (EDF). The laser is made of a 2 m long EDF where 30 mm of its end section is tapered to construct a microfiber knot resonator (MKR). The combination of the EDF and MKR generates a stable single wavelength laser at 1555 nm wavelength with a signal to noise ratio (SNR) of 33.7 dB using a 63 mW of 980 nm pump power. The peak wavelength of the laser can be tuned by 340 pm as the MKR diameter reduces from 5.0 to 0.5 mm with an acceptable penalty in output power.

In this paper we propose and demonstrate an S-band Brillouin–Raman Fiber Laser (BRFL). The S-band BRFL utilizes a Dispersion Compensating Fiber (DCF) as the non-linear gain medium in a linear cavity configuration and amplified by two 1425 nm, 380 mW pumped Raman Fiber Amplifiers (RFAs). A Brillouin Pump (BP) signal of 1515 nm at 12 dBm in power is injected into the setup to generate Stokes lines via the Stimulated Brillouin Scattering (SBS) process. The S-band BRFL is able of generating a Brillouin comb with 32 Stokes lines with a flat peak output power of − 18 dBm. The best BP to Stokes power ratio of the system is determined to be 50:50, while a ratio of 70:30 is observed to generate Stokes with a higher peak power, but at the expense of the number of wavelengths. The S-band BRFL has many potential applications as multiwavelength sources for communications and sensors.

We propose and demonstrate a simple and cost effective non-membrane optical microphone (OM) consisting of only a standard erbium doped fibre amplifier (EDFA) and a 25 km of conventional single mode fibre (SMF) as the sensing medium. A photo detector is used for data acquisition. The proposed setup utilizes the disturbances in the competing longitudinal modes in a low reflectivity fibre resonator whereby airborne acoustic waves impacting the surface of the fibre will modulate the intensity of the optical signal in the fibre. This modulation frequency is analyzed using the fast fourier transform (FFT) technique to extract the information embedded in the optical signal. The experiment shows that the system is capable of picking up the airborne acoustic waves and can find many potential applications.

A tunable up frequencies of microwave photonics based on stimulated Brillouin scattering (SBS) for application in radio over fiber is demonstrated. The experimental setup consists of 7.7 km dispersion compensated fiber, which acts as the nonlinear medium for generating the SBS and is pumped by a narrow linewidth (0.015 nm) tunable laser operating in L-band region. The input-modulated RF at 2 GHz is upshifted to new frequencies of 7.71, 7.68, 7.65, 7.62, 7.58, and 7.56 GHz at Brillouin pump wavelengths of 1580, 1585, 1590, 1595, 1600, and 1605 nm, respectively. This system allows certain tunability in the upshifted frequencies by using a tunable laser source. VC 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1710–1713, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26106

An investigation into the effect of semiconductor optical amplifier (SOA) location in an O-band Brillouin SOA fiber laser (BSFL) was performed. Better output peak power flatness was generated by placing the SOA after the nonlinear medium, which is a 20 km true wave fiber (TWF) than placing it before the TWF. A maximum power of six flat output peaks with average power of −22.0 dBm for a BP (Brillouin pump) wavelength of 1320 nm was obtained, generated from a BSFL with a SOA located after the TWF, compared with three flat Stokes signals with the SOA before the TWF at a BP wavelength of 1310 nm. The flat peak power output for the O-band Brillouin fiber laser is important, especially in producing a good O-band source.

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.

A first time O band Brillouin fiber laser is demonstrated and compared with the C band Brillouin fiber laser. By utilizing a 20 km True wave fiber (TWF), the experiment demonstrated four Brillouin lines generated from the simple set-up of Brillouin fiber laser. We compared the threshold between the Brillouin pump wavelength at 1310 nm which represent O band region and 1550 nm for C band region. It shows that the Brillouin threshold at O band region is smaller that C band. The channels spacing between these two bands are also different, where O band have 12.72 GHz spacing while 1550 nm have 10.25 GHz spacing.

A simple Erbium Doped Fiber Laser (EDFL) in linear cavity configuration is reported. The cavity design is based on an FBG as a back reflector, and a loop back optical circulator with an output coupler as the front reflector. Different coupling ratios of the coupler are tested and 50: 50 provides the highest coupling output power of 22.06 dBm (160.7 mW). The pump power conversion efficiency is about 95% when pumping with two pump lasers at 1460 and 1490 nm with combined pumping power of 545 mW. The laser output has a measured linewidth of 0.0179 nm.

Graphene, a 2D material, has been used for generation of pulse lasers due to the presence of its various fascinating optical properties compared to other materials. Hence in this paper, we report the first demonstration of a thulium doped fiber laser with a wavelength-tunable, passive Q-switched output using a graphene-polyvinyl-alcohol composite film for operation in the 2.0 µm region. The proposed laser has a wavelength-tunable output spanning from 1932.0 nm to 1946.0 nm, giving a total tuning range of 14.0 nm. The generated pulse has a maximum repetition rate and average output power of 36.29 kHz and 0.394 mW at the maximum pump power of 130.87 mW, as well as a pulse width of 6.8 µs at this pump power. The generated pulses have a stable output, having a signal-to-noise ratio of 31.75 dB, and the laser output is stable when tested over a period of 60 min. The proposed laser would have multiple applications for operation near the 2.0 micron region, especially for bio-medical applications and range-finding.

A multi-wavelength Brillouin fiber laser (BFL) is demonstrated by using dual-wavelength fiber in a 7.7 km dispersion compensating fiber (DCF) that is incorporated in a 49 cm Bismuth erbium-doped fiber laser. The BFL operates in C-band, which is shifted by 0.08 nm and amplified by a Raman pump (RP). The threshold power for BP pumps and the Raman pump is achieved at 7 dBm and around 35 mW, respectively. The exclusive and practical benefits of using reduced high nonlinear Bismuth-erbium doped fiber ( Bi-EDF ) in implementing a four-wave mixing (FWM) method for multi-wavelengths Brillouin fiber laser (BFL) applications are experimentally demonstrated. Coupled interactions of Brillouin, Raman, and FWM scattering explain the unique feature of proposed configuration.

By controlling the cavity loss of the modes using a variable optical attenuator, specific intensities of distributed modes can be fed back into the erbium-doped fiber to produce signals without mode competition, thus resulting in stable lasing as a means to overcome mode competition in a homogenous gain medium. Two lasing signals were obtained with peak powers of approximately −3.475 dBm and −4.386 dBm for wavelengths of 1,540 nm and 1,548 nm, respectively, with a side mode suppression ratio of more than 43 dB.

We propose and demonstrate a Multiwavelength Brillouin Bismuth/Erbium Fibre Laser (MBBEFL) with the ability to control the number of wavelength channels generated. A multi-wavelength comb output is obtained using a 7.7km DCF as a non linear gain medium to generate Stokes wavelengths through the process of Stimulated Brillouin Scattering (SBS). The DCF is pumped by a Raman pump source at 400mW to lower the dispersion loss and promote the generation of the Stokes wavelengths. A 49cm long Bismuth based Erbium Doped Fibre (Bi-EDF) is used as an optical amplifier to provide the necessary gain for the Brillouin Pump and also act as the gain medium for the generated Stokes signal.

Tunable spacing of O-band multi wavelength Brillouin fiber laser is demonstrated. The channel spacing is varied by employing two types of cavities. A full closed linear cavity produce multi wavelength Brillouin fiber laser with 12.5GHz while a ring cavity provide channel spacing of 25.0 GHz. By combining these two cavities and employing optical channel switch, the channel spacing are varied. The comparison of Brillouin threshold between O-band and C-band is demonstrated. In particular, an O-band transmission window is used instead of C-band due to its lower Brillouin threshold.

A dual-wavelength Erbium-doped fiber laser (EDFL) is demonstrated using a 1.5-m long EDF with a microfiber knot resonator (MKR) structure at the output end. The MKR is fabricated by heating and stretching a 3-cm long piece of EDF to form a microfiber, which is then manipulated to create a knot. The performance of the EDFL is investigated for two different MKR loop diameters. At a loop diameter of 4 mm, dual-wavelength laser is obtained at 1532.4 and 1556.0 nm with peak powers of −7.5 and −7.1 dBm and the corresponding optical signal-to-noise ratios of 22 and 32 dB, respectively. As the MKR diameter is reduced to 2 mm, the operating wavelength of laser shifts to a shorter wavelength, especially for the second lasing with a significant drop in output power due to the bending loss, which is more pronounced at smaller loop diameter. The slope efficiency of the EDFL drops from 0.55 to 0.09% as the MKR diameter decreases from 4 to 2 mm.

A thulium-doped fiber laser (TDFL) with a tunable Q-switched output is proposed and demonstrated. A silver nanoparticle based saturable absorber is used to generate the Q-switched pulses, while a tunable Mach-Zehnder filter acts as the wavelength-tuning mechanism. The TDFL has an operating wavelength range of 1916.5-1945.3 nm, with output pulses that have a repetition rate of 50.1 kHz and a pulse width of 5.1 μs, as well as a pulse energy of 69.3 nJ at the maximum pump power. The Q-switched pulses obtained are very stable and have a signal-to-noise ratio of 34.18 dB.

A compact, passively Q-switched fiber laser with a tunable output is demonstrated. The proposed system uses a short length ytterbium doped fiber to create a very stable and compact optical circuit that uses black phosphorus (BP) as a saturable absorber to generate the desired short pulses. A stable Q-switch pulse train is obtained, with an operational wavelength range from 1056.6-1083.3 nm. Concurrently, a maximum pulse energy and minimum pulse width as well as a repetition rate range of 7.1 nJ, 4 μs and 6.0-44.8 kHz respectively was obtained. The proposed system will be able to cater to a multitude of applications that require a compact yet robust and cost-effective pulse laser.

In this paper, we present the different amplitude flatness of O-band Brillouin fiber laser resulting from placing the O band semiconductor optical amplifier at different locations. Stable and flatter peaks of multiwavelength Brillouin were generated by placing the SOA after the nonlinear medium instead of placing it before the nonlinear medium. The maximum number of Stokes are also differs between both configuration where the maximum number of stokes achieved was 12 generated by 1320 nm Brillouin pump with spacing channels of 12.72 GHz.