Substrate-strain-induced tunability of dense wavelength-division multiplexing thin-film filters

Classic dense wavelength-division multiplexing thin-film filters can be spectrally tuned through the substrate's strain. We analyze the theoretical shift of the design wavelength of a narrow-bandpass filter when uniform, uniaxial compressive stress is applied to the substrate, and we compare calculated sensitivity with experimental data. We measure the transmittance shape of a 200-GHz standard filter for several loading cases to quantify the increase of insertion losses.     

Ring-resonator filters in silicon oxynitride technology for dense wavelength-division multiplexing systems

The design and characterization of ring-resonator-based filters with free spectral ranges of 100 and 50 GHz by use of SiO(x)N(y) technology is presented. Fiber-to-fiber insertion losses of 4.4 dB on the drop port and 2.1 dB on the through port have been achieved for a single-ring filter. An interleaver filter for a 25-GHz spaced dense wavelength-division multiplexing system with two cascaded rings is demonstrated. The filter has a 7.4-GHz bandwidth at -1 dB and an extinction ratio of 15 dB and is polarization independent.     

Soliton wavelength-division multiplexing system with channel-isolating notch filters

We propose a wavelength-division multiplexing system in which transmission of solitons is stabilized by fixed- or sliding-frequency notch filters (a soliton rail), providing channel isolation. We demonstrate analytically and numerically that a soliton trapped in a channel between two notches is very robust. We also predict an optimum ratio between the channel separation and the soliton's spectral width. The effects of interchannel collisions are considered, and it is demonstrated that these effects can be largely eliminated by notch filters, which require a compensatory gain that is comparable with the basic gain balancing the fiber loss.     

Promising compact wavelength-tunable optical add-drop multiplexer in dense wavelength-division multiplexing systems

We design and model a highly compact and tunable optical add-drop multiplexer (OADM) device that consists of long-period gratings and piezoelectric ceramic fiber stretchers. The proposed OADM shows that 50 dense wavelength-division multiplexing channel signals can be selected in the wavelength range from 1526.25 to 1563.75 nm with 0.75-nm channel spacing, which covers the whole C-band gain spectrum of an erbium-doped fiber amplifier. The cross talk between channels is less than -39 dB, and the total insertion loss of the device is approximately 0.24 dB, which includes the splicing losses, the mode mismatching loss, and the expected losses in the two side-by-side coupled fibers.     

Photon statistics of amplified spontaneous emission in a dense wavelength-division multiplexing regime

The photon statistics of amplified spontaneous emission in the few-modes regime and in single mode, conditions that are typical of dense wavelength-division multiplexing transmission, have been experimentally proved by direct detection. The dependence of the degeneracy factor for the Bose-Einstein distribution on the degree of second-order coherence of light is stated. The theoretical dependence of the number of amplified spontaneous emission modes on the ratio between the optical channel and the detector bandwidths has also been confirmed by experiments, thus quantifying the loss of validity of asymptotic approximations when they are extended to the few-modes regime.     

UV-written long-period waveguide grating coupler for broadband add/drop multiplexing

We demonstrate a UV-written polymer long-period waveguide grating (LPWG) coupler, which offers a bandwidth of ∼20 nm, a maximum coupling efficiency of ∼80% and ∼60% for the TE and TM polarizations, respectively, and a wavelength-tuning range over the (S + C + L)-band (∼140 nm) with a temperature control of ∼25 °C. The LPWG coupler has the potential to be developed into a practical broadband add/drop multiplexer for coarse wavelength-division-multiplexing applications.     

Periodic dispersion management in soliton wavelength-division multiplexing transmission with sliding filters

We compare the performance of dispersion-managed fibers with that of dispersion-decreasing fibers and of fibers with uniform dispersion in filtered soliton wavelength-division multiplexing transmission. Alternating-sign dispersion management allows us to achieve values of collision-induced timing jitter that are comparable with what can be achieved by use of dispersion-decreasing fiber and are lower for some parameter values.     

All-fiber zero-insertion-loss add-drop filter for wavelength-division multiplexing

We developed and fabricated an all-fiber add-drop filter by recording a Bragg grating in the waist of an asymmetric mode converter-coupler formed by adiabatic tapering and fusing of two locally dissimilar, single-mode optical fibers. The insertion loss of the device was ~0.1 dB .A narrow spectral bandwidth (<1 nm) and a large add-drop efficiency (>90%) were also demonstrated. In addition, the filter was polarization independent.     

Experimental test of dense wavelength-division multiplexing using novel, periodic-group-delay-complemented dispersion compensation and dispersion-managed solitons

In an all-Raman amplified, recirculating loop containing 100-km spans, we have tested dense wavelength-division multiplexing at 10 Gbits/s per channel, using dispersion-managed solitons and a novel, periodic-group-delay-complemented dispersion-compensation scheme that greatly reduces the timing jitter from interchannel collisions. The achieved working distances are approximately 9000 and approximately 20,000 km for uncorrected bit error rates of <10(-8) and <10(-3), respectively, the latter corresponding to the use of "enhanced" forward error correction; significantly, these distances are very close to those achievable in single-channel transmission in the same system.     

Reduction of collision-induced timing jitter in dense wavelength-division multiplexing by the use of periodic-group-delay dispersion compensators

We show how replacement of a modest fraction of the usual fiber-based dispersion compensation with a periodic-group-delay dispersion-compensating module can result in a drastic reduction in collision-induced timing jitter in dense wavelength-division multiplexing with dispersion-managed solitons. The principal mechanism here is a correspondingly large reduction in the net path over which a pair of colliding pulses interact.     

Suppression of the interactions between fibre gratings used as dispersion compensators in dense wavelength-division multiplexing systems

Chirped fibre Bragg gratings (CFBGs) are required to be concatenated to compensate the fibre dispersion in the dense wavelength-division multiplexing (DWDM) systems. When the channel spacing is small, the performance of CFBGs is degraded, which restricts the usage of fibre gratings. The origin of the interactions between the gratings is analysed and methods of suppressing the interactions are also proposed.     

Incompatibility of polarization-division multiplexing with wavelength-division multiplexing in soliton-transmission systems

In a recent experiment it was demonstrated that polarization-division multiplexing was incompatible with wavelength-division multiplexing. We discuss a theoretical model that explains this result.     

光波分复用实验的改进和扩展

利用自聚焦透镜代替集成的波分复用器件,对2路波分复用实验结构进行了改进,并在实验中增加光谱仪用于观察光纤中的光谱.通过上述改进,使学生进一步了解波分复用器内部结构,加深对复用和解复用的理解.     

High-order dispersion-managed solitons for dense wavelength-division multiplexed transmissions

Optimal dense wavelength-division multiplexed transmission is obtained based on high-order periodic dispersion-managed solitons in a dispersion-slope-compensated fiber link.     

Traveling-wave polymer devices as wavelength converters for wavelength-division multiplexing applications

Wavelength conversion of optical signals as a result of refraction through a moving interface in traveling-wave electro-optic phase modulators has been analyzed. The connection between wavelength conversion and phase modulation with velocity mismatch has been investigated both analytically and by use of computer simulation. The configuration of a device performing the conversion is proposed, and the operating requirements are determined. Devices based on the described technique are especially promising for wavelength conversion in wavelength-division multiplexing applications and possess several advantages over competing all-optical methods.     

Demonstration of massive wavelength-division multiplexing over transoceanic distances by use of dispersion-managed solitons

By combining a special dispersion map that has nearly constant path-average dispersion, a hybrid amplification scheme involving backward-pumped Raman gain, and sliding-frequency guiding filters, we have demonstrated massive wavelength-division multiplexing at 10 Gbits/s per channel, error free (bit-error rate, 相似文献   

Integrated-optical add/drop multiplexer for DWDM in lithium niobate

In this contribution, an add/drop multiplexer that uses a mode-selective coupler and a holographically recorded slanted Bragg grating in lithium niobate is demonstrated. A Bragg grating with a bandwidth of 0.1 nm allows for an add/drop efficiency of about 96% with a cross-talk well above 22 dB applicable for wavelengths in the 1.5 μm window. Polarisation-independent operation can be achieved by application of a bias electric field to compensate for the small mismatch of propagation constants of TE and TM modes. The proposed scheme of an integrated-optical lithium niobate based device appears to be an interesting option due to its potential for fast electro-optical switching. PACS 42.40.Ht; 42.65.Hw; 42.70.Ln; 42.82.Cr; 42.82.Et     

Single and double distributed optical amplifier fiber bus networks with wavelength-division multiplexing for photonic sensors

Two different optical fiber bus networks are compared and demonstrated experimentally as means of gathering information from four wavelength-division-multiplexed photonic sensors. Both topologies include distributed amplification, which allows one to overcome the limitation in the maximum number of sensors that can be multiplexed in a single structure. Results obtained with a dual-bus topology are compared with those achieved with a single-bus network.