公开(公告)号：US06381560B1

公开(公告)日：2002-04-30

申请号：US09457966

申请日：1999-12-09

Applicant: Virendra S Shah ,  Atul Kumar Srivastava ,  James William Sulhoff ,  Yan Sun ,  Liyan Zhang

Inventor： Virendra S Shah ,  Atul Kumar Srivastava ,  James William Sulhoff ,  Yan Sun ,  Liyan Zhang

IPC: G16F1750

CPC classification number: H01S3/06754 ,  H01S3/1608

Abstract: A method of modeling erbium doped fiber (“EDF”) for use in erbium doped fiber amplifiers (“EDFA”). The EDF has a length and a fractional population density of erbium ions in an excited state. Since the EDF supports N channels, the power propagation along the EDF is characterized by N+1 differential equations as a function of the direction of propagation, z, of the channels along the length l of the EDF and the time t. By applying an average inversion model to a spatially averaged inversion level of the erbium ions in the fiber, the N+1 partial differential equations are reduced to a single ordinary differential equation. This allows an analytical solution at the boundary and initial conditions of the fiber so that an expression for the power of the signal propagating along the fiber can be obtained. With this expression, the single equation can be solved analytically for the inversion level at any point along the EDF.

Abstract translation: 对掺铒光纤放大器（“EDFA”）中使用的掺铒光纤（“EDF”）进行建模的方法。 EDF具有处于激发态的铒离子的长度和分数种群密度。 由于EDF支持N个信道，沿着EDF的功率传播的特征在于沿着EDF的长度l和时间t的信道的传播方向z的函数的N + 1个微分方程。 通过将平均反演模型应用于光纤中铒离子的空间平均反演水平，将N + 1偏微分方程简化为单个常微分方程。 这允许在光纤的边界和初始条件下的解析解，使得可以获得沿着光纤传播的信号的功率的表达式。 通过这个表达式，可以在沿着EDF的任何点分析求解单个方程的反演水平。

公开(公告)号：US6151145A

公开(公告)日：2000-11-21

申请号：US10617

申请日：1998-01-22

Applicant: Atul Kumar Srivastava ,  Thomas Huntington Wood ,  John Lehrer Zyskind

Inventor： Atul Kumar Srivastava ,  Thomas Huntington Wood ,  John Lehrer Zyskind

IPC: H04B10/12 ,  H04J14/02

CPC classification number: H04B10/2507 ,  G07F17/3262

Abstract: A two-wavelength WDM analog CATV transmission system which utilizes wavelength channel spacing of about 2.2 nm and laser-dithering. The system includes a pair of optical transmitters (DBF lasers), a pair of modulators, a dithering device, a polarization controller, a 3-dB combiner, an optical amplifier (EDFA), an attenuator, a length of optical fiber, a filter and a CATV receiver. The two lasers have wavelengths of .lambda.1 and .lambda.2, where the difference between .lambda.1 and .lambda.2 is approximately 2.2 nm. The modulators are driven with analog signals comprising 77 NTSC channels between 55.25 and 535.25 MHz A 2-GHz dithering tone is applied to the .lambda.1 laser and the output of the .lambda.2 laser is passed through the polarization controller to align the polarization of the two transmitters. The two modulated and aligned outputs are combined by the 3-dB combiner and launched into the EDFA The output of the EDFA is divided by the splitter four ways and one of the four outputs is passed through the attenuator and launched into the transmitting end of the optical fiber. The receiving end of the fiber is connected to a filter, which provides input into the CATV receiver. By utilizing a wavelength channel spacing of about 2.2 nm and dithering one of the lasers, worst-channel Composite Triple Beat distortion is reduced to -60 dBc, an acceptable level for deployment of WDM analog CATV systems.

Abstract translation: 双波长WDM模拟CATV传输系统，其使用约2.2nm的波长信道间隔和激光抖动。 该系统包括一对光发射器（DBF激光器），一对调制器，抖动装置，偏振控制器，3-dB组合器，光放大器（EDFA），衰减器，一段光纤，滤波器 和CATV接收机。 两个激光器具有λ1和λ2的波长，其中λ1和λ2之间的差值约为2.2nm。 调制器由包括55.25和535.25MHz之间的77个NTSC通道的模拟信号驱动。将2GHz抖动色调施加到λ1激光器，并且λ2激光器的输出通过偏振控制器以对准两者的极化 发射机。 两个调制和对准的输出由3 dB组合器组合并发射到EDFA中EDFA的输出由分离器四路分配，四路输出之一通过衰减器并发射到发射端 光纤。 光纤的接收端连接到滤波器，该滤波器向CATV接收机提供输入。 通过利用大约2.2nm的波长信道间隔和抖动激光之一，最差信道复合三重节拍失真降低到-60dBc，这是用于部署WDM模拟CATV系统的可接受的水平。