Qiliang Li

A Novel Switchable Dual-Wavelength Ring Erbium-Doped Fiber Laser Operating in single-longitudinal-mode

In this paper, we demonstrate a simple switchable dual-wavelength ring erbium-doped fiber laser operating in single-longitudinal-mode (SLM) at room temperature. A pair of reflection type short-period fiber Bragg gratings (FBGs) is used as the wavelength-selective component of the laser. A segment of unpumped polarization maintaining erbium-doped fiber (PM-EDF) is acted as a narrow multiband filter. By turning the polarization controller (PC) to balance the gain and loss in the ring cavity, single-wavelength and dual-wavelength laser oscillations are observed. The output power variation is less than 0.6dB for both wavelengths over a five-minute period and the optical signal to noise (ONSR) is greater than 50dB.

Wavelength tunable single freqeuncy bistability erbium-doped fiber ring laser

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.

Impairment-aware dynamic RWA algorithm in multi-granularity WDM optical networks

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.

Performance analysis and optimization of various MG-OXCs multi- granularity WDM optical networks based on waveband switching

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.

Short cavity single-mode dual wavelength fiber laser array

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.