Abstract: Polarization-mode dispersion (PMD) of an optical device, i.e. fiber or component is effected by launching a first pump laser beam of a fixed wavelength, a probe laser beam with a second fixed wavelength and a second pump laser beam having a variable wavelength and a polarization direction orthogonal to the other two beams into an optical device to generate three output signals which are input into a semiconductor optical amplifier to generate four-wave mixing (FWM) products. The average PMD of the device is computed by measuring the power of the FWM products versus the wavelength of the second pump laser beam.

Abstract: An integrated optical dynamic channel equalizer that can be employed to equalize the channel gain level in a WDM transmission line and monitor the optical channel performance. The device consists of a circulator, a dynamic gain equalizer chip and a controller. Due to the simplicity of the dynamic gain equalizer chip, which includes one 1×n multiplexer/demultiplexer, an n-channel variable optical attenuator array (VOA-n), a partially transparent dielectric reflective means and an n-channel detector array, the device is very compact and can be fabricated at low cost. By placing a quarter wave plate between the n-channel variable optical attenuator array and the partially transparent reflective means in the dynamic channel equalizer chip, the device can be rendered polarization insensitive.

Abstract: An integrated optical dynamic channel equalizer that can be employed to equalize the channel gain level in a WDM transmission line and monitor the optical channel performance. The device consists of a circulator, a dynamic gain equalizer chip and a controller. Due to the simplicity of the dynamic gain equalizer chip, which includes one 1×n multiplexer/demultiplexer, an n-channel variable optical attenuator array (VOA-n), a partially transparent dielectric reflective means and an n-channel detector array, the device is very compact and can be fabricated at low cost. By placing a quarter wave plate between the n-channel variable optical attenuator array and the partially transparent reflective means in the dynamic channel equalizer chip, the device can be rendered polarization insensitive.

Abstract: A switchable dynamic gain-flattened optical amplifier with wide adjustable gain range is provided. Optical signals are amplified through common amplification such that the gain is approximately common to all optical signals. Further, gain specific amplification is then achieved through distinct amplification wherein the optical signal is routed through one of N parallel amplification paths each having its well-designed gain. The amplifier makes use of a control circuit to self-adjust quickly and respond to changes in input conditions, operating conditions of the optical amplifier and gain requirements while maintaining gain flatness and a low noise figure (NF) over a broad optical bandwidth and a wide range of gain levels. The optical amplifier is highly desirable in dense wavelength-division-multiplexed (DWDM) systems for responding to changes in operating conditions due to link loss, pump deterioration, channel add/drop, and network reconfigurations.

Abstract: Provided are optical amplifiers and method for amplifying an optical signal with an improved noise figure. This is achieved by exploiting the coherence (data) and incoherence of an optical. More specifically, an optical signal is split into two path signals that propagate and are amplified along two independent paths. The path signals each carry a signal path component and an external noise path component. After amplification the path signal each further carry an ASE (amplified spontaneous emission) path component wherein the ASE path components are un-correlated.

Abstract: A noise reduction apparatus used to increase the signal-to-noise ratio (SNR) of an optical signal is provided. The structure of the noise reduction apparatus may be based on the Mach-Zehnder interferometer. To increase the SNR, the noise reduction apparatus makes use of the coherence of a coherent component of an optical signal having a coherent signal power and the incoherence of an incoherent component of the optical signal having an incoherent signal power. The optical signal is split in two path signals with each path signal having the same intensity but a different phase. The phase difference is tuned in a manner which produces a main output optical signal containing most of the coherent signal power and containing a fraction of the incoherent signal power, with the remaining incoherent signal power being diverted to one or more subsidiary outputs.

Abstract: A very low noise figure optical amplifier is provided which includes a noise reduction apparatus as part of the structure of the optical amplifier. To improve the signal-to-noise ratio (SNR) of the amplified optical signal, the noise reduction apparatus makes use of the coherence of a coherent component of an amplified optical signal having a coherent signal power and the incoherence of an incoherent component of the amplified optical signal having an incoherent signal power. The amplified optical signal is split in two path signals with each path signal having the same intensity but a different phase. The optical path length the path signals is selected such that coherent path components are combined constructively at a main output while the power of the incoherent path components is divided between the main output and at least one subsidiary output. The result is an increase in the SNR, and a decrease in noise figure (NF) of approximately 3 dB.

Abstract: A switchable dynamic gain-flattened optical amplifier with wide adjustable gain range is provided. Optical signals are amplified through common amplification such that the gain is approximately common to all optical signals. Further, gain specific amplification is then achieved through distinct amplification wherein the optical signal is routed through one of N parallel amplification paths each having its well-designed gain. The amplifier makes use of a control circuit to self-adjust quickly and respond to changes in input conditions, operating conditions of the optical amplifier and gain requirements while maintaining gain flatness and a low noise figure (NF) over a broad optical bandwidth and a wide range of gain levels. The optical amplifier is highly desirable in dense wavelength-division-multiplexed (DWDM) systems for responding to changes in operating conditions due to link loss, pump deterioration, channel add/drop, and network reconfigurations.