The capacity of optical communication systems has shown an incredibly thriving growth from their inception to the last several decades. From the observations in traffic demand, the objectives of this thesis are to develop some key functions for improving the flexibility and efficiency of wavelength division multiplexing (WDM) and optical division multiplexing (OTDM) networks by using wavelength multicasting technique. Practically, at a photonic gateway, for the interconnection between WDM and OTDM networks, an nonreturn-to-zero (NRZ)-to-return-to-zero (RZ) waveform conversion is necessary due to the popular utilization of NRZ and RZ formats in WDM and OTDM networks, respectively. Moreover, if the waveform conversion combines with wavelength multicasting, multiple RZ signals will be generated, resulting in an increase of the throughput of network and the flexibility of wavelength assignment. A desirable stage after these conversions is to aggregate the higher bit-rates OTDM signals based on these lower bit-rates multicast RZ signals. The pulsewidth is one of the parameters to determine the bit-rates of OTDM signals. Therefore, to achieve the aggregate OTDM signals with flexible bit-rates adapting to specific network demand, it is necessary to manage the pulsewidth in a wide tuning range. In the first work, a NRZ data signal is injected into an highly nonlinear fiber (HNLF)-based four-wave mixing (FWM) switch with four RZ clocks compressed by a Raman amplification-based multiwavelength pulse compressor (RA-MPC).The pulsewidth of four multicast RZ signals is adjusted in a continuously large range from 12.17 to 4.68 ps by changing Raman pump power of RA-MPC. In addition, the sampling of optical signal waveform is necessary to monitor signals in optical network. The signals can always be analyzed off-line by capture-and-process-later techniques. However, it is challenging that these techniques are not compatible with instantaneous amplitude changes of signals as well as capturing the details and singular manners such as transient events which need real-time processing. Therefore, in the second work, an effort to characterize the waveform of signal in real-time using wavelength multicasting technique with multiwavelength sampling short-width pulses which are on the order of a few picoseconds is implemented. Using the short pulsewidths of the sampling pulses, it is possible to sample the signal precisely because its waveform does not change significantly in the sampling time. An all-optical waveform sampling of NRZ and RZ on-off-keying (OOK) signals is focused. The 4x10 GHz WDM sampling pulses are compressed with the pulsewidth which are less than 3 ps by RA-MPC and then interact with the input signal under test using FWM effect in an HNLF. Four obtained sampled signals result in a sampling rate of 40 GSample/s, therefore, the reconstructed waveforms are well-matched with the input signal waveforms. Moving to the phase-modulated signals, especially RZ-differential phase shift keying (DPSK) signal, it is attractive for RZ-DPSK signal due to its robust tolerance to the effects of some fiber nonlinearities, and the support of high spectral efficiency. Moreover, all-optical pulse compression has been widely investigated as one of the key elements to enable high bit-rate signals overcoming electronics limits. So far, pulse compression has often used before data modulation at the transmitter to generate high bit-rate signals. Our work, on the other hand, implements the pulse compression for RZ-DPSK signal for inline applications. A useful inline application of the data pulse compression is to generate an aggregate high-speed data rate based on optical time multiplexing of many channels with lower-speed data rates. The higher bit-rates of aggregate signals depend on the pulsewidths of lower bit-rate signals. Therefore, the compression of an inline 10 Gb/s RZ-DPSK signal using a distributed Raman amplifier-based compressor (DRA-PC) is done. The RZ-DPSK signal with pulsewidth of 20 ps after 30 km standard single mode fiber (SSMF) transmission is compressed down to in picoseconds duration such as 12, 7.0, and 3.2 ps. The pulse compression of the inline signal is applied in two works. In the first work, a compressed signal with the pulsewidth of 3.2 ps is multiplexed to a 40 Gb/s OTDM signal and then successfully de-multiplexed. The second application is wavelength multicasting of the inline compressed RZ-DPSK signal to get multicast signals with short-pulsewidths for increasing the throughput of network and wavelength resource. The DRA-PC compresses the inline RZ-DPSK signal with the obtained pulsewidths of 12, 7.0, and 3.2 ps which then interact with two continuous waves (CWs) in an HNLF-based FWM switch. Thus, the pulsewidths of the multicast signals were compressed down to 12.5, 7.89, and 4.27 ps. Finally, for networking between OTDM and WDM networks, an OTDM-to-WDM conversion is crucially required. However, it is given that in some cases, different WDM channels are expected to be generated in order to connect to each tributary of OTDM signal. In this work, a 20 Gb/s OTDM RZ-DPSK signal is converted to 4x10 Gb/s WDM RZ channels. One tributary of OTDM signal is converted to 2x10 Gb/s WDM RZ signals at two FWM products.
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机译：从开始到过去的几十年中，光通信系统的容量已显示出惊人的增长。从流量需求的观察来看，本论文的目的是开发一些关键功能，以利用波长组播技术来提高波分复用（WDM）和光分复用（OTDM）网络的灵活性和效率。实际上，在光子网关上，对于WDM和OTDM网络之间的互连，由于NRZ和RZ格式的广泛使用，必须进行不归零（NRZ）到归零（RZ）波形转换分别在WDM和OTDM网络中。此外，如果将波形转换与波长多播相结合，则会生成多个RZ信号，从而提高网络的吞吐量和波长分配的灵活性。这些转换之后的理想阶段是基于这些较低比特率的多播RZ信号聚合较高比特率的OTDM信号。脉冲宽度是确定OTDM信号的比特率的参数之一。因此，为了获得具有适应特定网络需求的灵活比特率的总OTDM信号，必须在较宽的调谐范围内管理脉冲宽度。在第一个工作中，将NRZ数据信号注入到基于高度非线性光纤（HNLF）的四波混合（FWM）开关中，该开关具有四个基于拉曼放大的多波长脉冲压缩器（RA-MPC）压缩的RZ时钟。通过更改RA-MPC的拉曼泵浦功率，可以在从12.17到4.68 ps的连续大范围内调整四个组播RZ信号的脉冲宽度。另外，光信号波形的采样对于监视光网络中的信号是必需的。始终可以通过捕获和处理后的技术离线分析信号。但是，具有挑战性的是，这些技术与信号的瞬时幅度变化以及捕获细节和奇异方式（例如需要实时处理的瞬态事件）不兼容。因此，在第二工作中，进行了使用具有几皮秒量级的多波长采样短宽度脉冲的波长多播技术来实时表征信号的波形的努力。使用采样脉冲的短脉冲宽度，可以对信号进行精确采样，因为其波形在采样时间内不会发生明显变化。聚焦NRZ和RZ开关键（OOK）信号的全光波形采样。 RA-MPC将4x10 GHz WDM采样脉冲压缩为小于3 ps的脉冲宽度，然后在HNLF中使用FWM效应与被测输入信号进行交互。获得的四个采样信号导致采样率为40 GSample / s，因此，重构的波形与输入信号波形完全匹配。转向相位调制信号，尤其是RZ差分相移键控（DPSK）信号，它对RZ-DPSK信号具有吸引力，因为它对某些光纤非线性的影响具有较强的耐受性，并支持高频谱效率。此外，全光脉冲压缩已被广泛研究为使高比特率信号能够克服电子技术极限的关键因素之一。到目前为止，在发送器进行数据调制之前，经常使用脉冲压缩来生成高比特率信号。另一方面，我们的工作为串联应用实现RZ-DPSK信号的脉冲压缩。数据脉冲压缩的一种有用的在线应用是基于具有低速数据速率的许多通道的光时多路复用来产生合计的高速数据速率。聚集信号的较高比特率取决于较低比特率信号的脉冲宽度。因此，使用基于分布式拉曼放大器的压缩器（DRA-PC）压缩了内联10 Gb / s RZ-DPSK信号。在30 km标准单模光纤（SSMF）传输之后，脉冲宽度为20 ps的RZ-DPSK信号被压缩到皮秒的持续时间，例如12、7.0和3.2 ps。在线信号的脉冲压缩在两个工作中应用。在第一个工作中，将脉冲宽度为3.2 ps的压缩信号多路复用为40 Gb / s OTDM信号，然后成功进行多路分解。第二个应用是对行内压缩的RZ-DPSK信号进行波长多播，以获得具有短脉冲宽度的多播信号，以增加网络和波长资源的吞吐量。 DRA-PC以12、7.0和3.2 ps的脉冲宽度压缩内联RZ-DPSK信号，然后在基于HNLF的FWM开关中与两个连续波（CW）相互作用。因此，多播信号的脉冲宽度被压缩到12.5、7.89和4.27 ps。最后，对于OTDM和WDM网络之间的联网，至关重要的是需要OTDM到WDM的转换。然而假定在某些情况下，为了连接到OTDM信号的每个支路，预期会产生不同的WDM信道。在这项工作中，将20 Gb / s OTDM RZ-DPSK信号转换为4x10 Gb / s WDM RZ通道。 OTDM信号的一个支路在两个FWM产品上转换为2x10 Gb / s WDM RZ信号。
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