Dispersion-imbalanced Loop Mirror Research Articles

Interferometric Noise Characterization and Suppression in Optical CDMA Networks

A solution for suppressing multiple-access interference and incoherent interferometric noise in 2-D optical code-division multiple access (CDMA) networks is demonstrated using a dispersion-imbalanced loop mirror containing a 15-m heavily GeO2-doped fiber. From the experimental study of the degradation caused by noise, bit-error-rate (BER) measurements in a two-user system having coherent, partially coherent, and incoherent interferometric noise without the dispersion-imbalanced loop mirror exhibit error floors above BER = 10-6. Including the dispersion-imbalanced loop mirror before the receiver allows error-free transmission, and reduces the power penalty from the noise by 7 dB. The solution presented increases the receiver sensitivity and accentuates the flexibility of the optical CDMA networks.

Wavelength-tunable dispersion-imbalanced loop mirror based on dispersion-flattened high-nonlinearity photonic crystal fiber and its application in suppression of the incoherent interferometric crosstalk

Wavelength-tunable nonlinear suppression of incoherent interferometric crosstalk has been experimentally demonstrated using the dispersion-imbalanced loop mirror based on a 64-m-long dispersion-flattened high-nonlinearity photonic crystal fiber. The signal quality improvement is achieved over a wavelength range of more than 25 nm (1545-1570 nm).

The role of positive pre-chirping on the nonlinear compression of a dual frequency beat signal with a dispersion imbalanced loop mirror

This work provides a detailed numerical analysis on the optimized compression of a dual frequency beat signal to generate a spectrally-enriched short-duration pulse train at 10 and 40 GHz frequencies. The effect of pre-chirping the beat signal on its compression characteristics using a dispersion imbalanced nonlinear optical loop mirror (DI-NOLM) is studied in detail. The output pulse quality is characterized by the shape of the pulse, peak-to-pedestal ratio, spectral content of the pulse and the energy contained in the pulse. It is found that suitable pre-chirping of the beat signal results in better shaping characteristics with significant pedestal suppression. The suitability of the shaped picosecond pulses for further spectral enrichment and the possibility of multi-wavelength generation are also studied.

All-optical wavelength conversion and multichannel 2R regeneration based on highly nonlinear dispersion-imbalanced loop mirror

All-optical wavelength conversion has been achieved to generate a multichannel return-to-zero optical source for wavelength-division-multiplexed (WDM) systems by using a nonlinear optical loop mirror consisting of a common dispersion-shifted fiber. After WDM transmission over 40-km SMF, the WDM signals are successfully regenerated by a novel regenerator including reshaping and reamplification based on a dispersion-imbalanced loop mirror consisting of an SMF and a highly nonlinear dispersion-shifted fiber.

2R regeneration based on dispersion-imbalanced loop mirror and its applications in WDM systems

2R regeneration based on dispersion-imbalanced loop mirror is investigated including the characteristics of transfer function, output extinction ratio, initial chirp, predispersion, and WDM signals transfer functions. Theoretical results show that the input peak power is a critical parameter for the dispersion-imbalanced loop mirror (DILM) and furthermore, to guarantee the multiwavelength operation of the DILM, limitations due to accumulated dispersion and dispersion slope have to be considered. Our experiment demonstrates that 6/spl times/10 Gb/s WDM signals can be successfully regenerated by a novel 2R regenerator based on a DILM consisting of a single mode fiber (SMF) and a highly nonlinear dispersion-shifted fiber (DSF) after WDM transmission over 40 km SMF of the WDM signals.

2R regenerator based on high non-linear dispersion-imbalanced loop mirror

A 2R regenerator is demonstrated for the first time based on high non-linear dispersion-imbalanced loop mirror (HN–DILM). Theoretical results show that the increment of the extinction ratio and Q-factor could be achieved by using the HN–DILM when carefully choosing the input peak power. The receiver sensitivity of a noise-loaded 10 Gbit/s signal is improved by 2.9 dB by using the 2R regenerator.

Interferometric noise suppression by means of dispersion-imbalanced loop mirror over a wavelength range of 28 nm

Signal quality enhancement and interferometric noise suppression have been demonstrated by nonlinear filtering in a dispersion imbalanced loop mirror. The nonlinear filter improves the signal extinction ratio by more then 10 dB and simultaneously increases the acceptable noise level by 15 dB. The improvement is constant throughout a wide wavelength range of 28 nm within the C-band erbium-doped fiber amplifier region.

A novel actively and passively mode locked fiber laser with dispersion-imbalanced loop mirror

In this letter, a dispersion imbalanced loop mirror (DILM) was constructed by the use of one segment of high dispersion fiber and another segment of much lower dispersion. Based on the nonlinear switching properties of the DILM, a 10 GHz actively and passively mode locked fiber laser was demonstrated for the first time to our knowledge. In this laser, the DILM was acted as not only a passive element to make further compression of the pulse but also an in-band ASE filter to increase the stability of the laser. Optical pulses possessing narrow pulse width (3.1 ps) and low timing jitter (400 fs) were generated successfully.

Spectral-smoothing and pedestal reduction of wavelength tunable quasi-adiabatically compressed femtosecond solitons using a dispersion-flattened dispersion-imbalanced loop mirror

A dispersion-flattened dispersion imbalanced nonlinear optical loop mirror is used to smooth the spectrum and reduce the pedestal of tunable femtosecond solitons generated via pulse compression in a dispersion-flattened dispersion decreasing fiber. Transform-limited pulses with durations less than 210 fs and peak-to-pedestal ratios greater than 40 dB are obtained over a wavelength range of 32 nm at a repetition rate of 10 GHz.

High-quality laser diode pulse compression in dispersion-imbalancedloop mirror

High-quality femtosecond pulse generation from a 1.5 µm gain-switched DFB laser diode in a compact nonlinear compressor based on a dispersion-imbalanced fibre loop mirror is reported. An overall compression ratio of 80 is achieved, resulting in generation of near-transform-limited pulses with negligible tails and a duration of 270 fs.

In-band amplified spontaneous emission noise filtering with a dispersion-imbalanced nonlinear loop mirror

This paper reports the removal of in-band amplified spontaneous emission (ASE) noise in a 10 Gb/s noise-loaded return-to-zero (RZ) signal using a dispersion-imbalanced loop mirror. The resulting receiver sensitivity is improved from -37.0 dBm to -37.7 dBm. The dependence of receiver sensitivity on the loop mirror bias is also investigated, and the optimal bias point is found to be where the loop transmissivity decreases with increasing input power.