Depressed-cladding Erbium-doped Fiber Research Articles

Depressed cladding erbium-doped fiber laser passively mode-locked with carbon nanotube saturable absorber

A depressed cladding erbium doped fiber (DC-EDF) laser with a carbon nanotube saturable absorber is proposed and demonstrated. The laser is able to generate a mode-locked output with a narrow pulse width of 0.77 ps at a lasing wavelength of 1496 nm. A 200 m long single-mode fiber together with the DC-EDF, with a negative and positive dispersion respectively is used to balance the effect of dispersion and the non-linearity of the system. The output is highly stable, with a signal to noise ratio in the radio frequency domain of 51.2 dB as well as a pulse energy, average output power and repetition rate of 58.9 pJ, −12.75 dBm and 900.9 KHz at the maximum pump power. The proposed laser would have significant applications for S-band communications systems.

Spooling diameter dependent Q-switched output in depressed cladding erbium doped laser with MoWS2 saturable absorber

A tunable, Q-switched depressed-cladding erbium-doped fiber (DC-EDF) laser employing a molybdenum tungsten disulfide (MoWS2) thin film as a saturable absorber (SA) is reported. The output of the laser can be controlled by adjusting the spooling diameter of the gain medium, with continuous wave operation obtained from 1466 nm to 1502 nm and 1473 nm to 1525 nm for DC-EDF spooling diameters of 5.5 cm and 6.5 cm respectively. The Q-switched output, obtained by incorporating an MoWS2 based SA into the cavity shortens the tuning range to between 1476.0 nm and 1496.0 nm as well as 1486.0 to 1496.0 nm for the same spooling diameters. The outputs have repetition rates ranging from 21.7 kHz to 44.6 kHz and a minimum pulse width and maximum pulse energy of 2.4 µs and 11.0 nJ, for the DC-EDF with a spooling diameter of 5.5 cm. The DC EDF with a spooling diameter of 6.5 cm is able to generate pulses with a repetition rate of between 32.2 kHz and 40.9 kHz with a minimum pulse width and maximum pulse energy of 2.8 µs and 10.1 nJ.

S-band SLM distributed Bragg reflector fiber laser

Generation of single longitudinal mode operation based on distributed Bragg reflector (DBR) cavity configuration, using a depressed-cladding erbium-doped fiber as the gain medium collectively with fiber Bragg grating (FBG) and Faraday rotator mirror (FRM) performing as the end mirrors, is proposed and demonstrated in this work for operation in the S-band region. The FBG has a central wavelength of 1506 nm, which functions to restrict the lasing frequency. A small line-width value measured at 20 kHz has been achieved in this system. A graph of average pump power against output power establishes the measured slope efficiency at about 0.01%.

Graphene based Q-switched tunable S-band fiber laser incorporating arrayed waveguide gratings (AWG)

We present in this paper, the result of successful fabrication of a novel graphene-based Q-switched fiber laser in the S-band region using an arrayed waveguide gratings (AWGs). The S-band lasing is realized by employing a depressed-cladding erbium doped fiber (DC-EDF), as the gain medium. A new ferrule-to-ferrule and stepwise optical extraction method is introduced and employed for depositing the thin graphene layer within the fiber laser cavity as the saturable absorber, while a tunable laser source (TLS) is used for depositing graphene onto the fiber ferrule. A demonstration of performance characteristics of this device is presented showing a Q-switched threshold of 65.29 mW and a range of repetition rate from 73.6 kHz to 331.1 kHz, with a linear increment. Minimum pulse duration of 1.218 μs is obtained at a pump power of 100.44 mW. Additional measurements are performed on the characteristics of the output power, pulse duration, pulse repetition rate, pulse energy, and peak power with respect to the pump power.

Optical Sensing Systems Based on Depressed Cladding Erbium Doped Fiber

This work describes new types of optical sensing systems based on Depressed Cladding Erbium Doped Fiber (DC-EDF). Due to the amplification characteristics developed for S-Band uses, this sensing system has high sensitivity, high dynamic range and wide bandwidth. It can be used to monitor static parameters such as force, pressure, displacement and dynamic parameters used in acoustics and vibrations. Two types of sensing systems with different approaches have been studied: the amplifier and the laser sensor. We describe the performance of these sensing systems in S band (1490 and 1510 nm) in static and dynamic conditions. We also appointed for some sensing applications for many areas of interest, such as, electric energy and civil engineering.

Tunable single longitudinal mode S-band fiber laser using a 3 m length of erbium-doped fiber

In this paper a tunable single-longitudinal mode (SLM), short-wavelength band (S-band) fiber laser using a conventional erbium-doped fiber (EDF) with a length of 3 m and a step index erbium dopant profile as opposed to the commonly used depressed cladding erbium-doped fiber (DC-EDF) is proposed and demonstrated. The proposed SLM fiber laser has a tuning range of 1496 to 1507 nm in a ring configuration using two 0.15 m of EDF which acts as saturable absorbers (SAs). The highest peak power measured is about −0.6 dBm at a wavelength range of 1502 to 1507 nm. The measured signal-to-noise ratio (SNR) is approximately 74 dB for the same wavelength range. The line-width of the SLM output is measured to be 140 kHz.

Enhancement of Brillouin Stokes generation in the S-band region using a combination S-band Depressed Cladding Erbium Doped Fiber and Semiconductor Optical Amplifier

A hybrid Depressed-Cladding Erbium Doped Fiber (DC-EDF) together with a broadband Semi-conductor Optical Amplifier (SOA) to enhance the generation of Stokes and anti-Stokes in a 7.7 km long Dispersion Compensating Fiber (DCF) is proposed and demonstrated. The performance of the proposed system is compared against that of a conventional system with only the DC-EDF as the gain medium, and the incorporation of the SOA can be seen to enhance the generation of Brillouin Stokes significantly. The proposed system is able to generate an output comb with a flat-top and more than 29 Stokes and 13 anti-Stokes lines, an increase of 14 and 8 lines respectively over the conventional system and covering the entire S-band region. The output comb generated is highly stable over time.

Gain-flattened S-band depressed cladding erbium doped fiber amplifier with a flat bandwidth of 12 nm using a Tunable Mach-Zehnder Filter

S-band amplification is an important area of optical communications research, focusing on meeting the ever-increasing demands for traffic bandwidth as the C- and L-bands approaches to their limits. In this paper a novel method of providing an S-band optical amplifier with a flat gain-bandwidth is proposed. The proposed method utilizes a Depressed Cladding Erbium Doped Fibre together with a Tunable Mach-Zehnder Filter as to generate a flat amplification bandwidth of 12 nm stretching from 1492 to 1504 nm. The average gain value is approximately 24.21 dB, with a peak to peak fluctuation of 0.83 dB and a noise figure ranges from 7.13 to 10.94 dB for input signals of 1484 to 1510 nm.

Bending Sensor Based on $S$-Band Depressed Cladding Erbium-Doped Fiber

This work describes a new type of bending sensor based on depressed cladding erbium-doped fiber. Due to the amplification characteristics developed for S-band uses, this sensor has high sensitivity, broad dynamic range, and wide bandwidth. It can be used to monitor static parameters such as force, pressure, displacement, and dynamic parameters used in acoustics and vibration. We describe the sensor characterization in 1490 and 1510 nm in two different conditions: static and dynamic, in frequencies from 25 Hz to 10 kHz.

Numerical Modeling of S-Band EDFA Based on Distributed Fiber Loss

A numerical model for the analysis and design of S-band erbium-doped fiber amplifiers has been developed. The model is able to accurately predict the amplifier performances by taking into account the amplified spontaneous emission suppression due to the bending, as well as leakage losses of the fiber used as active medium. The model has been validated by comparing numerical and experimental data of bending loss, amplifier gain, and noise figure of an S-band optical amplifier based on a depressed-cladding erbium-doped fiber. A good agreement has been verified by varying fiber bending radius, input signal power, and wavelength. The model has been then applied to the optimization of the amplifier performances for wavelength-division multiplexer applications. The numerical results show that 20-25 dB gain can be achieved over a 25-30 nm range centered in a different part of the S-band from 1460 to 1525 nm, just by changing the bending radius and the length of a depressed-cladding fiber.

S-band depressed-cladding erbium-doped fiber amplifier with double-pass configuration

A new S-band erbium-doped fiber amplifier module with a double-pass configuration based on two circulators has been designed and constructed. The bending losses of a depressed-cladding doped fiber have been exploited to suppress the amplified spontaneous emission in the C band. The experimental characterization of the double-pass amplifier has shown that significant advantages can be obtained with respect to the single-pass configuration.

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

AbstractA 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

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.