Showing papers by "Harith Ahmad published in 2008"
TL;DR: In this paper, a linear cavity Brillouin fiber laser (BFL) is proposed and demonstrated for multi-wavelength operation, which uses a single mode fiber (SMF) as a nonlinear gain medium.
Abstract: A linear cavity Brillouin fiber laser (BFL) is proposed and demonstrated for multi-wavelength operation. The BFL uses a single mode fiber (SMF) as a non-linear gain medium and an optical circulator to generate a linear cavity resonator. Two couplers are used to inject the Brillouin Pump (BP) and tap the BFL output respectively. The effect of the coupler ratio on the BFL performance is studied by keeping constant the ratio of the first coupler and varying the ratio of the second coupler. 11 simultaneous lines with a line spacing of 0.8 nm are obtained at a BP of 11.7 dBm and a coupler ratio of 95:5. The laser output is stable at room temperature with 5 lines obtained at above – 30 dBm, and has the largest signal to noise ratio observed at the remaining lines. The proposed BFL has the advantage of being able to operate at any wavelength and is only dependent on the available BP wavelength.
72 citations
TL;DR: A configuration for linear cavity Brillouin fiber laser generation is demonstrated using a standard single-mode fiber, two optical circulators, a 3 dB coupler, and a 95/5 coupler to allow high efficiency.
Abstract: A configuration for linear cavity Brillouin fiber laser (BFL) generation is demonstrated using a standard single-mode fiber, two optical circulators, a 3 dB coupler, and a 95/5 coupler to allow high efficiency. With a Brillouin pump (BP) power of 13 dBm, the laser peak power is 12.3 dB higher than a conventional linear cavity BFL at an upshifted wavelength of 0.086 nm from the BP wavelength. In addition, it is revealed that the BFL peak power can be higher than the transmitted BP peak power when the BP power exceeds the second Brillouin Stokes threshold power.
60 citations
TL;DR: In this paper, a quad-wavelength fiber ring laser using a semiconductor optical amplifier (SOA) as gain medium and an array waveguide grating (AWG) as a selective wavelength filter is proposed and demonstrated.
Abstract: A quad-wavelength fiber ring laser using a semiconductor optical amplifier (SOA) as a gain medium and an array waveguide grating (AWG) as a selective wavelength filter is proposed and demonstrated. The quad-wavelength fiber ring laser is capable of generating four laser wavelengths at 1531.0 nm, 1533.3 nm, 1535.7 nm, and 1538.0 nm with a peak power at –20 dBm and a channel spacing of 0.24 nm (300 GHz) corresponding to the channel spacing of the selected AWG ports. The quad-wavelength ring laser shows stable operation over time with negligible fluctuations in the peak power of the lasing wavelengths. The separation of the two lasing wavelengths can be tuned over several nanometers by changing the ports of the AWG. The proposed laser configuration has the advantage of stable quad-wavelength output at room temperature as well as a simple and compact design with many potential DWDM and sensor applications.
58 citations
TL;DR: In this article, a multi-wavelength laser is demonstrated using stimulated Brillouin scattering in a singlemode fiber with a feedback loop using two couplers and an optical circulator.
Abstract: A multi-wavelength laser is demonstrated using stimulated Brillouin scattering in a single-mode fiber with a feedback loop using two couplers and an optical circulator. This Brillouin fiber laser can operate at any wavelength depending on the Brillouin pump (BP) wavelength used. With a BP of 14 dBm, approximately 8 to 10 BFL lines are obtained in both forward and backward directions respectively with a line spacing of 0.16 nm. The use of the 99/1 coupler and 50/50 coupler gives the highest power and number of lines for the forward and backward outputs respectively. The maximum Stokes power obtained is approximately 8.0 dBm. The anti-Stokes lines are also obtained due to four wave mixing and bidirectional operation. The combination of forward and backward output can generate a larger number of lines with channel spacing of 0.08 nm.
56 citations
TL;DR: In this paper, a simple fiber optic displacement sensor is presented using a multimode plastic bundled fiber and the intensity modulation technique, and the performance of the sensor is compared for different types of probes and targets.
Abstract: A simple fiber optic displacement sensor is presented using a multimode plastic bundled fiber and the intensity modulation technique. The performance of the sensor is compared for different types of probes and targets. The probe with the largest receiving core diameter demonstrates the highest linearity range, and increasing the number of receiving cores increases the sensitivity of the sensor. With a stainless steel target and the concentric bundled fiber with 16 receiving fibers as a probe, the sensitivity of the sensor is found to be 0.0220 mV/μm over 150 to 550 μm range and – 0.0061 mV/μm over 1100 to 2000 μm range. The target with a higher reflectivity shows a higher sensitivity. The linearity range for the front slope is almost similar for all targets tested. However, for the back slope, lower reflectivity objects have a relatively higher linearity range with the highest range of 1600 μm being obtained using plastic and aluminum targets. The simplicity of the design, high degree of sensitivity, dynamic range, non-contact measurement and low cost of the fabrication make it suitable for applications in industries for position control and micro displacement measurement in the hazardous regions.
50 citations
TL;DR: In this paper, a bidirectional multi-wavelength Brillouin fiber laser (BFL) generation is demonstrated using a 25 km long single-mode fiber as a Brillour gain medium in a ring cavity.
Abstract: Bidirectional multiwavelength Brillouin fiber laser (BFL) generation is demonstrated using a 25 km long single-mode fiber as a Brillouin gain medium in a ring cavity. Odd-order Brillouin Stokes waves appear in the backward direction whereas Brillouin pump and the even Stokes orders are in the forward direction with the line spacing 0.16 nm (∼20 GHz) between each two consecutive waves in forward and backward directions. In addition, by a combination of the backward and forward outputs, we have a higher number comb generation of a multiwavelength BFL with the line spacing 0.08 nm (∼10 GHz). The proposed configuration can work at any wavelength which is a benefit to the others.
45 citations
TL;DR: In this article, a new pressure sensor based on fiber Bragg gratings (FBG) is described with high pressure sensitivity, which is configured by embedding the FBG in a polymer-field aluminum casing with an opening on one side.
Abstract: A new pressure sensor based on fiber Bragg gratings (FBG), is described with high-pressure sensitivity. The sensor is configured by embedding the FBG in a polymer-field aluminum casing with an opening on one side, which is exposed to pressure measurand. The measured pressure response is 0.06 nm/psi that is ∼2700 times higher than the pressure response measured with a bare FBG. The linearity of the designed sensor is also shown to be good at pressures below 50 psi. This sensor has numerous potential applications in the area of low-pressure measurements. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 60–61, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23021
37 citations
TL;DR: In this article, an efficient erbium andytterbium-doped fiber amplifier (EYDFA) was demonstrated by forward and backward pumping a 3 m erbiam/ytter bium co-oped fibers (EYDF) in single-and double-pass configurations using a 20mW pump.
Abstract: An efficient erbium–ytterbium-doped fiber amplifier (EYDFA) is demonstrated by forward and backward pumping a 3 m erbium/ytterbium co-doped fibers (EYDF) in single- and double-pass configurations using a 20 mW pump. At the input signal wavelength of 1536 nm, the forward- and backward-pumped double-pass amplifiers achieved a maximum low-signal gain of 37.2 and 28.6 dB and a corresponding noise figure of 5.4 and 10.8 dB, respectively. Whereas, the forward- and backward-pumped single-pass amplifiers (at the same wavelength) achieved a maximum low-signal gain of 20.0 and 22.2 dB and a corresponding noise figure of 4.6 and 10.3 dB, respectively. The double-pass design offers an economical solution to high-efficiency and high-gain optical amplifiers.
21 citations
TL;DR: In this paper, a simple fiber optic displacement sensor based on intensity modulation technique is demonstrated using a bundle multimode plastic fiber as a probe, which consists of a light source, a probe and photodiode detector.
Abstract: A simple fiber optic displacement sensor based on intensity modulation technique is demonstrated using a bundle multimode plastic fiber as a probe. The sensor consists of a light source, a probe, and photodiode detector. The sensor is capable of measuring displacements of mirror ranging from 0.05 to 2.2 mm using a red light source of wavelength 632.8 nm with maximum output power of 1 mW. The sensitivity of the device is found to be 168.8 mV/mm over 0.05-0.35 mm range and -29.8 mV/mm over 1.05-2.2 mm range. The sensor is highly sensitive at the front slope and very useful for close distance target. The simplicity of the design, high degree of sensitivity, dynamic range and the low cost of the fabrication make it suitable for applications in industries as position control and micro displacement measurement in the hazardous region. © 2008 Wiley Periodicals, Inc.
21 citations
TL;DR: In this paper, the Brillouin laser was used to generate up to 3 Stokes and 3 anti-Stokes lines in the 1560 nm region at a channel spacing of 0.09 nm.
Abstract: Brillouin fibre laser is demonstrated using a very short length of photonic crystal fibre (PCF). A simple ring resonator is used in the experiment which consists of a 20 m long highly nonlinear PCF and 49 cm long Bismuth-based erbium-doped fibre (Bi-EDF). The proposed Brillouin laser is able to generate up to 3 Stokes and 3 anti-Stokes lines in the 1560 nm region at a channel spacing of 0.09 nm.
18 citations
TL;DR: In this article, a multi-wavelength Brillouin/erbium-doped fiber laser (BEFL) operating in the 1573 nm region is proposed and demonstrated, which employs both linear and nonlinear gain from a bismuth-based erbium-based EDF approximately 215 cm long and a single mode fiber of various lengths to generate an optical comb with a spacing of approximately 0.089 nm.
Abstract: A multi-wavelength Brillouin/erbium-doped fiber laser (BEFL) operating in the 1573 nm region is proposed and demonstrated. The system employs both linear and nonlinear gain from a bismuth-based erbium-doped fiber (Bi-EDF) approximately 215 cm long and a single mode fiber (SMF) of various lengths to generate an optical comb with a spacing of approximately 0.089 nm. Two 3 dB couplers were used to form a looping arm in the system in order to produce cascaded Brillouin Stokes waves as internal feedback for multi-wavelength operation. A stable output laser comb with 10 lines at more than − 13 dBm was obtained with 4.85 dBm Brillouin pump power and two 140 mW pumps at 1480 nm. The 1480 nm pumps' power and SMF length have a significant effect on the number of wavelengths and on the output power of the generated wavelength comb.
TL;DR: In this article, a double-pass EDFA with macro bending was used to suppress the spontaneous emission at the longer wavelength in order to achieve a high amplification in the shorter wavelength.
Abstract: Gain and noise figure improvements are demonstrated in a shorter wavelength region of a double-pass EDFA using a macrobending approach. The EDF is wound in a small radius to suppress the amplified spontaneous emission at the longer wavelength in order to achieve a high amplification in the shorter wavelength. Gain enhancements of about 12-14 dB are obtained with macrobending at the wavelength region between 1480 and 1530 nm. The macrobending also reduces the noise figure of the EDFA at wavelengths shorter than 1525 nm with a maximum improvement of 25 dB.
TL;DR: Surprisingly, it is revealed that the SBS threshold reduction depends strongly and solely on Raman gain and it is independent of the Raman pumping schemes.
Abstract: The effects of backward, forward, and bidirectional Raman pumping schemes on stimulated Brillouin scattering (SBS) is investigated in this study By using a linear cavity, we utilize residual Brillouin pump (BP) and Raman pump (RP) power after each transmission through a 25 km single-mode fiber (SMF) used as a gain medium The SBS threshold power is reduced in the forward, backward, and bidirectional Raman pumping schemes by 25, 175, and 275 dB, respectively when the 1480 nm RP power is fixed at 150 mW and the BP wavelength is 1580 nm Surprisingly, it is revealed that the SBS threshold reduction depends strongly and solely on Raman gain and it is independent of the Raman pumping schemes In addition, the effect of Raman amplification on SBS is more effective at the SBS threshold, especially in the bidirectional and forward schemes
TL;DR: A self-calibrating automated characterization system for depressed cladding applications is demonstrated utilizing the laboratory virtual instrument engineering workbench (LabVIEW) software and general purpose interface bus (GPIB) interface.
Abstract: A self-calibrating automated characterization system for depressed cladding applications is demonstrated utilizing the laboratory virtual instrument engineering workbench (LabVIEW) software and general purpose interface bus (GPIB) interface. The automation system consists of a tunable laser source (TLS), optical spectrum analyzer (OSA), attenuator, laser diode controller, and a personal computer, and all these instruments are networked using GPIB cables. Compared to manual measurement techniques, the overall experiment time is reduced by 80% while the data acquisition increases in accuracy, with a lower uncertainty value of plusmn 0.012 dB after self-calibration. From the experiment, the use of the automated self-calibrating software has allowed for the characterization of the depressed cladding erbium-doped fiber (EDF).
TL;DR: In this paper, a 2 × 2 coupler at the end of the linear cavity was used to increase the number of Stokes lines in the 1590-nm region at a channel spacing of 0.089 nm.
Abstract: A new linear cavity BEFL configuration for increased Stokes-line generation is proposed and demonstrated utilizing a 2 × 2 coupler at the end of the linear cavity. The proposed linear cavity is able to generate up to 33 Stokes lines in the 1590-nm region at a channel spacing of 0.089 nm. The Stokes lines are generated at a BP power of 4 dBm and a 1480-nm pump power of 100 mW. The number of Stokes generated by the proposed BELF is higher compared to conventional BEFL configurations in which the 2 × 2 coupler is placed in the middle of the linear cavity. The number of Stokes lines generated is observed to depend on the 1480-nm pump power as well as the operating wavelength region, which must be as close as possible to the lasing bandwidth of the free-running BEFL. The proposed multiwavelength BEFL is able to operate stably at room temperatures and is also compact due to the use of a 215-cm bismuth-based EDF as the linear gain medium.
TL;DR: In this paper, the effect of varying the modulation frequency on the laser output power was investigated, and it was shown that by incorporating the LiNbO3 modulator in the laser cavity, the sidemode suppression ratio (SMSR) of the laser is significantly improved and a higher peak power can be obtained at a higher current.
Abstract: A semiconductor optical amplifier (SOA) fiber-ring laser (SOAFRL) utilizing a fiber-Bragg grating (FBG) and lithium niobate (LiNbO3) modulator is demonstrated. The laser operates at a wavelength of 1547.64 nm, which is equal to the Bragg wavelength in the saturation region. By removing the LiNbO3 modulator in the ring, the laser shows a single-wavelength output, which has a lower peak power. The experimental results show that when reaching the saturation level, the system with the LiNbO3 modulator shows a higher saturation current and peak power compared to that of the system without the modulator. The effect of varying the modulation frequency on the laser output power is investigated. By incorporating the LiNbO3 modulator in the laser cavity, the side-mode suppression ratio (SMSR) of the laser is significantly improved and a higher peak power can be obtained at a higher current.
TL;DR: In this paper, a multi-wavelength laser operating on the basis of stimulated Brillouin scattering (SBS) is demonstrated in a single mode fiber (SMF) coupled with a feedback loop and an optical circulator.
Abstract: A multiwavelength laser operating on the basis of stimulated Brillouin scattering (SBS) is demonstrated in a single mode fiber (SMF) coupled with a feedback loop and an optical circulator. Ten simultaneous Stokes and anti-Stokes lines are obtained with a line spacing of either 0.08 or 0.16 nm at a Brillouin pump (BP) power of 14 dBm. The use of a 50/50 fused coupler gives the highest number of lines at a Stokes power of approximately 8 dBm. The anti-Stokes lines are generated by four-wave mixing and bidirectional operation of the system. This Brillouin fiber laser (BFL) is capable of operating at any wavelength, depending completely on the BP wavelength. Due to the built-in feedback mechanism, its operation is free from the need for any additional active linear gain medium, such as erbium-doped fibers used in a Brillouin erbium fiber laser. Further, the SMF can in principle be replaced with a highly nonlinear waveguide, such as a photonic crystal waveguide, to make a compact multiwavelength BFL.
01 Dec 2008
TL;DR: In this paper, the EDF is wound in a small radius to suppress the amplified spontaneous emission at the longer wavelength in order to achieve a high amplification in the shorter wavelength region between 1480 nm and 1530 nm.
Abstract: Gain and noise figure improvements are demonstrated in a shorter wavelength region of double-pass EDFA using a macro-bending approach The EDF is wound in a small radius to suppress the amplified spontaneous emission at the longer wavelength in order to achieve a high amplification in the shorter wavelength Gain enhancements of about 12 ~ 14 dB are obtained with macro-bending at wavelength region between 1480 nm and 1530 nm The micro-bending also reduces the noise figure of the EDFA at wavelengths shorter than 1525 nm with maximum improvement of 25 dB
TL;DR: In this paper, a dual-pumping scheme was used for ground state absorption to enhance the excited state absorption provided by the main pump of 1050 nm and thus to improve the gain and noise figure of the TDFA.
Abstract: An efficient fluoride-based thulium-doped fiber amplifier (TDFA) is theoretically demonstrated using a dual pumping scheme. Differential equations are solved directly in the theoretical analysis. An auxiliary pump at 1560 nm is used for ground-state absorption to enhance the excited-state absorption provided by the main pump of 1050 nm and, thus, to improve the gain and noise figure of the TDFA. A gain improvement of more than 10 dB is obtained at the 1470-nm region with the use of a 1560-nm pump at 20 mW. A small signal gain as high as 30 dB is obtained at this region with 100 mW of a 1050-nm pump and 20 mW of a 1560-nm pump using a 20-m of thulium-doped fiber. The corresponding noise figure is obtained at lower than 5 dB.
TL;DR: In this paper, a fiber-bragg grating (FBG) was used in the free-running ring laser (SOAFRL) to achieve a lower peak power as well as a broader bandwidth as the current is increased.
Abstract: A semiconductor optical amplifier fiber ring laser (SOAFRL) utilizing a Fiber Bragg Grating (FBG) is demonstrated. The laser operates at a wavelength of 1547.64 nm, equal to the Bragg wave-length. By removing FBG, the SOAFRL shows a multi-modes output due to the resonant characteristics of the semiconductor optical amplifiers (SOA's) gain. The output power ripple is observed around 5 dB. The experimental results show that when the saturation level is reached, the SOAFRL with the FBG shows a higher saturation current and peak power compared to that of the SOAFRL without the FBG. Mode competition in the cavity for the free-running ring SOAFRL results in a lower peak power as well as a broader bandwidth as the current is increased. By incorporating the FBG in the SOAFRL, a losing wavelength is generated and as such the side mode suppression ratio (SMSR) of the laser is significantly improved, resulting in a higher peak power at higher bias currents.
TL;DR: In this article, an efficient linear cavity Brillouin fiber laser (BFL) was demonstrated using a standard single mode fiber (SMF), an optical coupler and a fiber Bragg grating (FBG).
Abstract: An efficient linear cavity Brillouin fiber laser (BFL) is demonstrated using a standard single mode fibre (SMF), an optical coupler and a fiber Bragg grating (FBG). The laser peak is obtained at −4.5 dBm with a Brillouin pump of 14 dBm. The use of a 99/1 optical coupler shows the highest output because of the low loss in the cavity. The BFLs can be used to reduce the laser linewidth and technical noise. PACS: 42.60.Da; 42.81.−i; 42.81.Wg; 42.81.Uv © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 265–266, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23077
TL;DR: In this article, a dual-stage S-band erbium-doped fiber amplifier (S-band EDFA) is demonstrated using a broadband fiber Bragg grating (FBG) operating in the conventional-band (C-band) region or a C-band/Sband wavelength division multiplexing (WDM) coupler which filters out the forward Cband amplified spontaneous emission (ASE) in the amplifier system, thus increasing the population inversion in the Sband region.
Abstract: Gain improvement in a dual-stage S-band erbium-doped fiber amplifier (S-band EDFA) is demonstrated using a broadband fiber Bragg grating (FBG) operating in the conventional-band (C-band) region or a C-band/S-band wavelength division multiplexing (WDM) coupler which filters out the forward C-band amplified spontaneous emission (ASE) in the amplifier system, thus increasing the population inversion in the S-band region. The gain for the amplifier with the WDM coupler increases by about 8.5 dB with an input signal power of −40 dBm, compared to that of the conventional dual-stage amplifier. The gain improvement varies from 4.0–9.2 dB at a wavelength region between 1480 to 1512 nm without a significant noise figure penalty.
TL;DR: In this article, a triple-wavelength fiber ring laser using a semiconductor optical amplifier (SOA) in conjunction with an array waveguide grating (AWG) is presented.
Abstract: We propose and experimentally demonstrate a triple-wavelength fiber ring laser using a semiconductor optical amplifier (SOA) in conjunction with an array waveguide grating (AWG). The experimental results show three lasing lines with an adjustable wavelength separation and a large optical signal-to-noise ratio under room temperature. The three channels operate at 1531.5 nm, 1532.3 nm and 1533.1 nm with a peak power above -23 dBm and optical signal to noise ratio above 30 dB at SOA drive current of 350 mA. By changing the ports of the AWG, the center wavelengths of the tri- ple lasing lines can be changed and the wavelength separation between the lasing lines can also be changed. The proposed laser configuration has the advantages of a simple and compact structure, quad-wavelength operation and the system can be upgraded to generate more wavelengths.
TL;DR: In this paper, a simple fiber laser configuration based on a semiconductor optical amplifier (SOA) is proposed for obtaining multi-wavelength oscillation at room temperature, in which a Sagnac loop mirror is used as the wavelength selective component.
Abstract: A simple fiber laser configuration based on a semiconductor optical amplifier (SOA) is proposed for obtaining multi-wavelength oscillation at room temperature, in which a Sagnac loop mirror is used as the wavelength selective component. The SOA has a flat gain of approximately 23dB within a bandwidth of 12 nm at a small input signal power. The loop mirror was constructed using a 3dB coupler and polarization maintaining fiber (PMF). The output spectrum of the proposed laser can be adjusted by controlling the bias current of the SOA and is quite stable at room temperature. At a bias current of 150 mA, six lines are obtained with at least −40 dBm output power and 25dB signal-to-noise ratio (SNR). The channel spacing and number of lines is determined by the length of polarization maintaining fiber (PMF) used in the loop mirror. The channel spacing of the proposed laser is 1.49 nm with a PMF 3 m. The multi-wavelength comb output can also be tuned by adjusting the operating temperature of the SOA. The multi-wav...
TL;DR: In this article, a forward-pumped double-pass EYDFA was demonstrated using 3 m of doped fiber with 20 mW pump power, achieving a maximum low signal gain of 37 dB and a corresponding noise figure of 5.5 dB.
Abstract: A compact and efficient optical amplifier is demonstrated using an erbium–ytterbium-doped fiber amplifier (EYDFA) with a double-pass configuration. It uses only 3 m of doped fiber with 20 mW pump power. This forward-pumped amplifier achieves a maximum low signal gain of 37 dB and a corresponding noise figure of 5.5 dB. Compared with the backward-pumping double-pass EYDFA, the gain obtained is 7 dB higher, with a lower noise figure of 5.5 dB. In addition, the gain obtained in this study is 17 dB higher than that of a conventional forward-pumping single-pass amplifier, while its noise figure is only 0.5 dB higher. These results show that the forward-pumped double-pass design holds great promise in the development of practical and cost-efficient optical amplifiers which can be pumped by using LEDs or low cost laser diodes.
01 Jan 2008
TL;DR: In this paper, a stable dual-wavelength fiber ring laser using an SOA in conjunction with an array waveguide grating (AWG) was demonstrated under room temperature conditions.
Abstract: It is demonstrated a stable dual-wavelength fiber ring laser using an SOA in conjunction with an array waveguide grating (AWG) The experimental results show stable dual lasing lines with an adjustable wavelength separation and a SNR of over 30 dB under room temperature The first channel operates at 15302 nm laser wavelength with an output power of approximately -11 dBm at a saturation current of 150 mA The second channel operates at either 15328 nm or 15388 nm with a maximum output power of more than -24 dBm By changing the ports of the AWG, the center wavelengths of the two lasing lines and wavelength separation can be tuned under room-temperature
01 Jan 2008
TL;DR: In this paper, a single-wavelength Brillouin fiber laser (BFL) is demonstrated at 1550nm region using Raman amplification in single mode fiber, which is up-shifted by 0.08nm from the BrillOUin pump with a peak power of -26.2 dBm and a side mode suppression ratio (SMSR) of more than 12 dB.
Abstract: A single-wavelength Brillouin fibre laser (BFL) is demonstrated at 1550nm region using Raman amplification in single mode fiber. The BFL operates at 1550.09nm, which is up-shifted by 0.08nm from the Brillouin pump with a peak power of -26.2 dBm and a side mode suppression ratio (SMSR) of more than 12 dB. The threshold power for Brillouin pump and Raman pump is obtained at around 5∼6dBm and 250mW, respectively for the case of 70~90% of the pump powers is injected into the SMF. The generated BFL has narrow linewidth and many potential applications such as in optical communication and sensors.
01 Jan 2008
TL;DR: In this paper, a flat gain erbium-doped fiber amplifier (EDFA) operating in the 1550 nm to 1590 nm region is demonstrated, which uses only a 15m EDF as opposed to a standard L-band EDFA which requires significantly longer EDF lengths.
Abstract: A flat gain erbium-doped fiber amplifier (EDFA) operating in the 1550 nm to 1590 nm region is demonstrated. The EDFA uses only a15m EDF as opposed to a standard L-band EDFA which requires significantly longer EDF lengths. The EDF is fabricated using a Modified Chemical Vapor Deposition process in conjunction with a solution doping technique. The NA, cut-off wavelength and erbium ion concentration of the fiber are obtained at 0.15, 998 nm and 900 ppm respectively. The gain of the EDFA is flattened to a level of about 12 dB with a gain variation of less than 3 dB over a range from 1550 to 1590 nm with a 1480nm pump at 90mW. This amplifier operates on the energy transfer of the quasi-two-level system, whereby the C-band energy acts as a pump for the population inversion required for gain at the longer wavelength. The noise figure at the flat gain region varies from 6 to 8.5 dB.
TL;DR: In this article, an erbium-doped fiber amplifier based on an unique narrowband amplified spontaneous emission (ASE) feedback technique is demonstrated by incorporating a series of fiber Bragg grating at the output end of the amplifier, which acts as an additional signal to limit the population inversion and clamps the amplifier's gain.
Abstract: All-optical gain clamping of an erbium-doped fiber amplifier (EDFA) based on an unique narrowband amplified spontaneous emission (ASE) feedback technique is demonstrated by incorporating a series of fiber Bragg grating at the output end of the amplifier. The reflected ASE acts as an additional signal to limit the population inversion and clamps the amplifier's gain. The gain of the proposed amplifier is clamped at 26.5 dB with dynamic input signal power up to -14 dBm and gain variation of less than 0.1 dB. The corresponding noise figure is less than 6.9 dB. The absence of any oscillating laser in this technique is advantageous since it can avoid relaxation oscillation effect.