Showing papers by "Sulaiman Wadi Harun published in 2005"

An efficient S-band erbium-doped fiber amplifier using double-pass configuration

Abstract: An efficient short wavelength band erbium-doped fiber amplifier (S-band EDFA) is proposed and demonstrated using double-pass configuration. This amplifier provides a gain as high as 30dB, but using only 15m depressed cladding erbium-doped fiber (EDF) and 130mW of 980nm pump power. Compared to the single-pass configuration, this amplifier shows a gain enhancement of about 14dB for pump powers above 120mW. However, noise figures penalties of about 0.5 ∼ 0.9dB are obtained for these pump powers. The proposed double-pass amplifier will play an important role in the development of a practical S-band EDFA from perspective of economical usage of EDF and pump power.

S-band erbium-doped fiber ring laser using a fiber Bragg grating

Abstract: A short wavelength band erbium-doped fiber laser (S-band EDFL) is demonstrated utilizing a fiber Bragg grating (FBG) in unidirectional ring configuration. The amplification in S-band is achieved using an erbium-doped fiber with depressed cladding, which suppressed gains at longer wavelength. The laser operates at 1500 nm, which coincides with the FBG wavelength. The optimum EDFL operation is obtained by routing only 10% of the laser output into the cavity. The laser has an output power of 7.8 dBm, more than 60 dB of peak to floor separation and 3 dB bandwidth of less than 0.08 nm. This fiber laser provides an inexpensive source for tunable output in the wavelength range from 1480 to 1520 nm.

S-band Brillouin erbium fibre laser

Abstract: A multi-wavelength Brillouin erbium fibre laser, which operates in short wavelength band (S-band), is proposed and demonstrated. The system employs both linear gain and nonlinear gain from a 20 m S-band erbium-doped fibre and a 500 m singlemode fibre, respectively, to generate an optical wavelength comb with spacing of approximately 0.084 nm. Two 80/20 couplers were used in the system as an internal feedback of generated Stokes signal to produce cascaded Brillouin Stokes for multiwavelength operation. A stable output laser comb of up to seven lines was obtained with a Brillouin pump of 3.5 mW and a 980 nm pump of 200 mW.

Gain enhancement in partial double‐pass L‐band EDFA system using a band‐pass filter

Abstract: The partial double-pass L-band erbium-doped fiber amplifier with enhanced gain characteristic is demonstrated using a band pass filter (BPF). The BPF is incorporated in the double-pass route to suppress the amplified spontaneous emission from the single-pass output for gain enhancing. The gain of 51.5 dB is obtained for the proposed amplifier at input signal power of -40 dBm, which is approximately 5.2 dB higher compared with the system without the BPF. However, the insertion loss of the BPF contributes to a small noise figure penalty in the system. This amplifier can be easily modified to support dense wavelength division multiplexing system application by using multiple channel BPFs or interleaver.

Effect of doped-fiber\s spooling on performance of S-band EDFA

Abstract: The effect of doped-fiber's spooling on performance of short wavelength band erbium-doped fiber amplifier (S-band EDFA) is demonstrated. Changing the spooling diameter resulted in a variation of gain and noise figure characteristics of this amplifier. The optimum spooling diameter is obtained in the range from 5 to 7 cm. Beyond this range, an inevitable degradation of gain and noise figure characteristics is observed due to the changes of phase matching wavelength. Therefore, maintaining the optimum spooling diameter is the important issue for the S-band EDFA.

A Partial Double-Pass S-Band Erbium-Doped Fibre Amplifier

Abstract: An efficient and low noise short wavelength band erbium-doped fibre amplifier (S-band EDFA) is proposed and demonstrated using double-pass configuration. This amplifier provides a gain of 1500 nm signal as high as 26.9 dB, which is 9.6 dB higher than the two-stage single-pass amplifier. The corresponding noise figure obtained is 7.5 dB, which is of the same level as in the single-pass amplifier and more than 2 dB lower than the previously reported double-pass amplifier [IEICE Electron. Express 2 (2005) 182]. The gain enhancement is due to the double pass-propagation of the test signal in the second stage, which increases the effective erbium-doped fibre (EDF) length. The low noise is attributed to the optical circulator between EDFs, which prevents the backward amplified spontaneous emission from propagating into the input part of the amplifier. The proposed amplifier is expected to play an important role in the development of a practical S-band EDFA.

Gain control in S-band erbium-doped fiber amplifier using a fiber bragg grating

Abstract: A gain-clamped short wavelength band erbium-doped fiber amplifier (S-band EDFA) is demonstrated utilizing a fiber Bragg grating (FBG). The amplification in S-band is achieved using an erbium-doped fiber (EDF) with depressed cladding design, which suppressed amplified spontaneous emission (ASE) at longer wavelength. The gain clamping is achieved by routing back the forward ASE into the feedback loop as to create a ring laser. The clamped gain is controlled using a variable optical attenuator (VOA) as to generate a gain of 14.6 to 25.2dB for input signal at 1504nm. At VOA = 0dB, the gain is clamped at 14.6dB with a gain variation of less than ±0.5dB for input signal at 1504nm with power dynamic range of -40 to -5dBm. The noise figure penalty is less than 0.8dB in this amplifier since the laser is arranged to be co-propagated with the signal.

An enhanced S-band brillouin/erbium fiber laser with an additional EDFA in sub-loop

Abstract: An enhanced short wavelength band brillouin erbium fiber laser (S-band BEFL) is demonstrated using an additional erbium-doped fiber amplifier (EDFA) in the sub-loop of the laser system. Compared with the conventional BEFL without the EDFA, the enhanced BEFL has improved the number of channels as well as the tuning range which are determined by the re-injected signal power. The incorporation of the EDFA also reduces the power difference between the first Stokes and the second Stokes from 17.2dB in conventional BEFL to 3.8dB in the proposed BEFL. A stable output laser comb with 8 channels was obtained with Brillouin pump of 5mW and signal at 1502nm. The BEFL has the potential to be used in the future dense wavelength division multiplexing communication system.

Two-stage S-band erbium-doped fiber amplifier using a depressed-cladding fiber

Abstract: A two-stage short-wavelength-band erbium-doped fiber amplifier (S-band EDFA) is demonstrated using a depressed-cladding erbium-doped fiber (EDF). The EDF has a fundamental-mode cutoff wavelength of about 1525 nm in order to suppress amplified spontaneous emission at the longer wavelength. The highest gain curve is obtained by setting the first- and second-stage pumps at 85 and 190 mW, respectively, where the unsaturated gains are obtained at about 28 dB. The gain was limited by the 12-dBm saturation power of the amplifier. The unsaturated noise figure ranged from 8.5 to 9.3 dB for all pump combinations tested. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 46: 92–94, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20910

Gain-clamped double-pass S-band erbium-doped fiber amplifier

Abstract: Gain clamping in double-pass short-wavelength band erbium-doped fiber amplifier (S-band EDFA) is demonstrated. It uses a fiber Bragg grating, which operates in conventional-band to form an oscillating laser in the cavity using an erbium-doped fiber (EDF) gain at around 1530nm. This new technique has shown a good gain clamping effect with gain variation of less than 1.0dB from -40 to -14dBm input signal powers for 1500nm signal. The gain can be controlled within 18 to 20dB by varying a variable optical attenuator from 0 to 8dB. Compared with an unclamped amplifier, the noise figures for small signals are slightly improved due to the suppression of amplified spontaneous emission (ASE). However, the noise figure level is still considerably high due to the double-pass scheme and unoptimised splicing between a depressed cladding EDF and a standard single mode fiber. The advantage of this gain clamped amplifier is that the oscillating light operates at wavelength outside S-band region, which prevent the wavelength division multiplexed system from being disturbed.

Effect of a midway isolator on the performance of two-stage S-band EDFA

Abstract: The effect of employing a midway isolator in a two-stage short-wavelength-band erbium-doped fiber amplifier (S-band EDFA) is demonstrated. The gain and the noise figure are improved for the system with a midway isolator as compared to the system without a midway isolator. These improvements are attributed to the suppression of the backward-propagating ASE. For an amplifier with a midway isolator, the small signal gain can reach approximately 30 dB, which is about 15 dB higher than in the system without the midway isolator, and the saturated power can be up to 12 dBm for an input power of 0 dBm. Noise figure reductions of about 1.2 to 2.8 dB are obtained in the input signal power region from -40 to -8 dBm with the midway isolator.

Additional EDFA Induced Flatness of Brillouin Stokes Peak Power

Abstract: An effect of incorporating an additional erbiumdoped fiber amplifier in the sub-loop of Brillouin/Erbium fiber laser (BEFL) is studied. Compared with the conventional BEFL without the additional EDFA, the enhanced BEFL has improved the flatness of the Brillouin Stoke’s peak power which peak power variation for the first six Stokes is reduced from 52.61 dB to 1.62 dB. The enhanced BEFL also increases the number of channels in the system by increasing the re-injected signal power. A stable output laser comb with 16 channels was obtained with Brillouin Pump of 2.5 mW and BP signal at 1561 nm.

Gain Improvement in Two-stage L-Band EDFA with Incorporation of Fiber Bragg Grating

Abstract: The gain improvement in two-stage long wavelength band erbium doped fiber amplifier (L-band EDFA) is demonstrated by incorporation of broadband C-band fiber Bragg grating (FBG). The FBG is used to reflect the unwanted backward C-band ASE from second stage back into the system. The proposed technique has improved the small signal gain from 19.6 dB to 23.5 dB compared to those of an amplifier without the FBG. Besides gain improvement, this technique also reduces noise figure and the maximum noise figure improvement of 1.8 dB was obtained at input signal power of 0 dBm. At wavelength range from 1570 to 1600 nm, the gain of the proposed amplifier varies from 20.0 to 28.5 dB. The flat-gain is expected to be obtained by optimization of EDF length and pump powers. The corresponding noise figures are varied from 4.8 to 5.2 dB.