Abstract: An apparatus and a method for accurately detecting Loss of Optical Power (LOS) by noise power cancellation effect and optical power is measured at two output ports of an athermal periodic filter, wherein one output port in the optical frequency domain, is aligned with the signal channels of an input WDM signal (on-grid port), whereas the second output port is aligned complementary to the first output port (off-grid port). In a preferred embodiment, the apparatus computes the ratio of the measured optical powers at the two output ports of the periodic filter, and comparing them to a threshold value that is determined from the overall common-mode rejection ratio (CMRR) of the detection apparatus. In an alternative embodiment, the apparatus additionally compares the optical power measured at the on-grid port to a threshold power that is determined from system design parameters.

Abstract: An apparatus and a method for accurately detecting Loss of Optical Power (LOS) by noise power cancellation effect and optical power is measured at two output ports of an athermal periodic filter, wherein one output port in the optical frequency domain, is aligned with the signal channels of an input WDM signal (on-grid port), whereas the second output port is aligned complementary to the first output port (off-grid port). In a preferred embodiment, the apparatus computes the ratio of the measured optical powers at the two output ports of the periodic filter, and comparing them to a threshold value that is determined from the overall common-mode rejection ratio (CMRR) of the detection apparatus. In an alternative embodiment, the apparatus additionally compares the optical power measured at the on-grid port to a threshold power that is determined from system design parameters.

Abstract: An apparatus and method for generating chirp-free return-to-zero differential phase-shift keyed optical signals using a modulator driven by at least one 3-level return-to-zero drive signals.

Abstract: Optical signal-to-noise ratio (OSNR) monitoring methods and apparatus are described. A tunable optical filter filters an optical channel containing an optical signal and noise. The total signal and noise power at the output of the filter is measured as the transmittance passband of the filter is varied and the maximum and minimum powers are determined. The ratio between the maximum and minimum powers is then used to determine the OSNR of the optical channel, which, for example, can be a wavelength channel in a wavelength division multiplexing (WDM) system. The ratio of the maximum signal power to the minimum signal power and the ratio of the maximum noise power to the minimum noise power are pre-determined based on the signal modulation format type and filter passband characteristics.

Abstract: Apparatus and methods for generating chirped return-to-zero (CRZ) differential quadrature phase-shift keyed (DQPSK) optical signals using a single modulator driven by synchronous return-to-zero (RZ) drive signals to achieve simultaneous RZ pulse formatting and chirped DQPSK data modulation.

Abstract: Optical signal-to-noise ratio (OSNR) monitoring methods and apparatus are described. A tunable optical filter filters an optical channel containing an optical signal and noise. The total signal and noise power at the output of the filter is measured as the transmittance passband of the filter is varied and the maximum and minimum powers are determined. The ratio between the maximum and minimum powers is then used to determine the OSNR of the optical channel, which, for example, can be a wavelength channel in a wavelength division multiplexing (WDM) system. The ratio of the maximum signal power to the minimum signal power and the ratio of the maximum noise power to the minimum noise power are pre-determined based on the signal modulation format type and filter passband characteristics.

Abstract: A method and apparatus for transmitting optical pulses in a dispersion-managed optical transmission system comprises determining the pulse width of optical pulses in a optical transmission channel in accordance with the path-average dispersion (PAD) experienced by that channel.

Abstract: Apparatus and methods for generating chirped return-to-zero (CRZ) differential phase-shift keyed (DPSK) optical signals using a single modulator driven by synchronous return-to-zero (RZ) drive signals to achieve simultaneous RZ pulse formatting and chirped DPSK data modulation.

Abstract: An apparatus and method for generating chirp-free return-to-zero differential phase-shift keyed optical signals using a modulator driven by at least one 3-level return-to-zero drive signals.

Abstract: A system and method for generating multilevel coded optical signals for optical transmission are disclosed. The method comprises driving modulators with synchronous data signals having the same data rate to generate a multilevel optical signal using differential phase shift keying and amplitude shift keying modulation.

Abstract: A method and apparatus for transmitting optical pulses in a dispersion-managed optical transmission system comprises determining the pulse width of optical pulses in a optical transmission channel in accordance with the path-average dispersion (PAD) experienced by that channel.

Abstract: A method and apparatus for transmitting a modulated optical signal includes a continuous source of light, a first optical modulator for generating an optical pulse stream in response to a radio frequency (RF) driving signal and a DC bias signal, and a second modulator for modulating the optical pulse stream with an electrical data signal. A processor dithers the phase of the RF driving signal using a first dither signal and the level of the DC bias signal using a second dither signal. The processor detects the first and/or second dither signals in the modulated optical signal and adjusts the phase of the RF driving signal and/or level of the DC bias signal to null the detected first and/or second dither signal.

Abstract: A method and apparatus for transmitting a modulated optical signal includes a continuous source of light, a first optical modulator for generating an optical pulse stream in response to a radio frequency (RF) driving signal and a DC bias signal, and a second modulator for modulating the optical pulse stream with an electrical data signal. A processor dithers the phase of the RF driving signal using a first dither signal and the level of the DC bias signal using a second dither signal. The processor detects the first and/or second dither signals in the modulated optical signal and adjusts the phase of the RF driving signal and/or level of the DC bias signal to null the detected first and/or second dither signal.

Abstract: A sub-miniature push-on RF connector for connecting a transmission line to a signal sink. The connector has a shielded transmission line section having a signal line and a ground line extending axially through the connector. A center pin is coupled to the signal line and extends from the center of a front face of the connector in an axial direction. A semicircular tab coupled to the ground line extends from the front face of the connector substantially along the length of the center pin and partially surrounding the center pin to reduce an air gap impedance, the tab having first and second wire bonding surfaces at the ends of the semicircular shape thereof and disposed adjacent to said center pin.