A widely tunable single-wavelength Brillouin fiber laser (BFL) incorporating a bismuth-based erbium-doped fiber (Bi-EDF)
is proposed. The 52 cm-long highly erbium-doped Bi-EDF provides broadband gain extending from the C-band (1525-1565
nm) to the L-band (1565-1625 nm). In experiment, the BFL operates in a range from 1555 nm to 1632 nm, which is the
widest to the best of our knowledge. The proposed BFL is an attractive narrow linewidth laser source on the L-band, which
has many potential applications, such as in slow light, coherent communication, and interferometric sensing.
Multi-granularity optical cross-connects (MG-OXC) is proposed as a promising technique to reduce the cost of the optical nodes in the wavelength division multiplexing (WDM) optical networks. In this paper, we use the on-line Maximize the Number of Waveband Route (MNWR) algorithm to evaluate the performance and optimize the design of multi-granularity optical WDM networks based on two different MG-OXCs: the serial MG-OXCs and the interconnecting MG-OXCs. The numerical results show that our optimal design can significantly reduce the network complexity and the blocking probability.
In practical multi-granularity WDM optical networks, optical signals will be degraded due to impairments mainly
introduced by a number of multi-granularity optical cross-connects (MG-OXC) and fiber links. Even worse,
transmission impairments will make the bit-error rate to be unacceptable. We investigate the impact of transmission
impairments on optical signal quality in multi-granularity WDM optical networks. A novel dynamic impairment-aware
RWA algorithm is proposed based on the presented transmission impairments model. We also evaluate the proposed
algorithm in the serial cascaded MG-OXCs network and the interconnecting MG-OXCs network by simulations.
In this paper, a short polarization-maintaining Er:Yb co-doped fiber laser is experimented. A pair of FBGs are
written in the Er:Yb co-doped sensitive fiber using UV beams. A 976nm pumping laser diode is used, and output
wavelength is selected by two FBGs. The PM Er:Yb co-doped fiber is used to main the orthogonal polarizations SM
lasing stability. The SM operation in each wavelength has been verified. On the basis of previous short cavity fiber,
a simple DBR dual wavelength fiber laser array has been designed and experimented. Two sections of short Er:Yb
co-doped fiber cavities are pumped by a 976nm LD simultaneously. The pump laser is splitted to pump each Er:Yb
co-doped fiber. It used a WDM coupler at 1550nm to connect the output port of two DBR fiber laser, an isolator is
spliced to the common arm of the WDM and used as the output port. The dual wavelength spacing is 0.31nm. The
output power reaches 6mW with the optical signal to noise ratio of greater than 30dB. A 12.5Gb/s codes rate is used
in the fiber laser transmission experiment. A nice optical eye diagram is recieved after long distance single-mode
communications fiber transmission.
In this paper, a tunable single-frequency fiber laser is designed. For narrow linewidth and single frequency
operation, a length of 2.75m unpumped EDF as a saturable absorber is used. The FBG combined with the unpumped
EDF provides narrow frequency selection. Counter propagating beams in the unpumped EDF form a standing wave
that results in periodic spatial hole burning. This creates a narrower bandwidth absorption grating than the FBG. The
output laser wavelength can be changed from 1530nm to 1570nm by the FBG. The 3dB spectrum width of output
laser is 0.08nm and the side mode suppression ratio is 55dB. The maximum output power exceeds 12mW, and the
stability is less than ±0.005dB. A nice single-frequency laser is observed. From the relationship of the pump power
and output power, it is obvious that the optical bistability switchable phenomena is showed in output characteristics.
The bistability switchable phenomena is caused by the saturable absorber in the ring cavity. A 10Gb/s codes rate is
used in the fiber laser transmission experiment. The high speed optical signal is transmitted in long distance without
regeneration. The eye diagrams of optical transmission are measured, the performance of long haul transmission
with high speed modulation is perfect.
A ring-cavity Er/Yb co-doped fiber laser (EYDFL) was designed and the characteristics was studied in this paper. It used
1064nm Nd:YAG laser as its pump, and the gain medium is a 4.1m-long EYDF. The single longitudinal-mode operation
is realized by introducing a fiber Bragg grating (FBG) as narrow wavelength-selective element, and a section of EDF
not-pumped as saturable absorber. The fiber laser resonator has been optimized, and the stable laser output with single
longitudinal-mode was got. In the simulation and experimental study, the difference of fiber laser output power using
output coupler in different coupling ratio has been studied. The optimal coupling ratio testified in experiments was near
80 percents. The effects and influences of saturable absorber on characteristics of output laser mode are analyzed.
A novel gain-clamped Long wavelength band erbium doped fiber amplifier (L-band EDFA) based on ring erbium-doped
fiber laser cavity was demonstrated. By using a fiber Bragg grating (FBG) at the output end of the amplifier, a portion of
forward conventional band (C-band) amplified spontaneous emission (ASE) was reflected back into the system, this new
design provided a good gain clamping and decreased noise effectively. It used 1480nm laser diode (LD) to pump high
Er3+ −concentration erbium-doped fiber for higher efficiency and lower noise figure (NF). The gain was clamped at
17.5dB with a variation of 0.3 dB from input signal power of -30dBm to -12dBm for a pump power of 180mW. By
adjusting the intra-cavity loss, the gain reached 19.78dB with inputting small signal and NF below 5dB was obtained. At
the longer wavelength (1614nm) of L-band 9.2dB gain was obtained.
A single-mode Er/Yb-codoped short cavity fiber laser was experimented on the basis of previous short cavity fiber laser.
The single-mode operation is realized by using the FBG and a 10cm section of Er/Yb co-doped fiber as a short cavity.
The output power exceeds 1.5mW for pump power of 80mW. The linewidth of output laser was measured as 2MHz at
1532.64nm, and the side mode suppression ratio was 55dB. The single-mode was observed by an interferometer with
free spectrum range (FSR) of 7.5GHz, and the longitudinal-mode fabric is analyzed. Relative intensity noise was less
A novel super-fluorescence fiber source (SFS) in the wavelength range that covers the C+L-band with stable spectrum, high output power and high slope efficiency is demonstrated. The topology consists of two stages: the first stage provides primarily the L-band gain spectrum whilst the second is solely for the C-band. These two stages are combined in series. We merely used the low erbium-doped fiber (EDF) 10.8m long as a gain medium in the second stage, which was pumped backward by a 980nm semiconductor laser diode (LD). As a result, the Amplified Spontaneous Emission (ASE) spectrum had a threshold of 5.1mW and a slope efficiency of 13.48% in the C-band. With a 980 nm LD pumping forward at 11-m-long moderate EDF and 58-m-long low EDF in series, L-band ASE was yielded with 52.3 mW threshold and a slope efficiency of 35.82% in the first stage. The ASE in the L-band was put into the second stage through an isolator and combined with C-band ASE as an output then a broad ASE spectrum of C+L-band was observed. The maximum output power of the C+L-band source was 33mW (15.3dBm) and its power stability was better than ±0.02 dB. Through the optimization of fiber parameters and the adjustment of pumping power in both stages, the flatness of ASE spectrum was improved. The optical bandwidth for the SFS output power, which ripples in 3 dB, was 63.7 nm (1536.92-1600.62 nm) of optical bandwidth without gain flattening filter.
Based on the analysis of conventional L-band EDFA we demonstrate a novel structure that improves the L-band amplification performances. In conventional L-band EDFA, 35nm (±1dB) flattened amplification bandwidth from 1565 to 1600 nm is obtained. Small signal gain of 25dB is achieved at 1590 nm with input power of -30dBm and the saturated output power reach to 10dBm. The linear relation between pump power and signal power are demonstrated experimentally. By utilizing a fiber Bragg grating (FBG) with center wavelength of 1550 nm, the population inversion of EDFA is intensified, which gives rise to gain improvement. Experimental results show that the signal gain is enhanced by the FBG by more than 8dB. The use of FBG has also shown a better performance in gain clamping. The amplifier gain is clamped at 25dB with a gain variation of less than 0.5dB for input power as high as -15dBm.