Abstract: Methods of converting silica to silicon and fabricating silicon photonic crystal fiber (PCF) are disclosed. Silicon photonic crystal fibers made by the fabrication methods are also disclosed. One fabrication method includes: sealing silica PCF and a quantity of magnesium within a container, the quantity of magnesium defined by 2Mg(g)+SiO2(s)?2MgO(s)+Si(s); converting silica PCF to a reacted PCF through magnesiothermic reduction; and converting the reacted PCF to the fabricated silicon PCF by selective dissolution of the reacted PCF in an acid. Another fabrication method includes: adding silica PCF and a quantity of solid magnesium to an unsealed container, the quantity of magnesium substantially in excess of that defined by 2Mg(g)+SiO2(s)?2MgO(s)+Si(s); converting silica PCF to a reacted PCF through magnesiothermic reduction; and converting the reacted PCF to the fabricated silicon PCF by selective dissolution of the reacted PCF in an acid.

Abstract: Systems and methods of electronic wavefront correction are disclosed. An example method receiving an optical signal representing a wavefront traveling along a plurality of propagation paths, and electronically correcting distortion in the wavefront. An example apparatus includes an receiver and an electronic wavefront corrector. The receiver is configured to coherently receive an optical signal representing a wavefront traveling along a plurality of propagation paths. The electronic wavefront corrector is configured to correct phase distortion in the wavefront.

Abstract: Efficient apparatus, methods, systems and devices to generate, transmit and detect optical differential polarization-phase-shift keying signals are disclosed for high spectral efficiency optical communication systems. It includes an electrical encoder and an optical encoder for generation of differentially encoded polarization-phase modulated optical signals and optical demodulators and balanced detectors for detection of the optical signals. The optical signals are transmitted through optical fiber links or free space. The electrical encoder maps independent data channels into differentially-encoded data sequences. In the optical encoder, the encoded data sequences from the electrical encoder drive optical modulators to generate differentially-encoded polarization-phase modulated optical signals at a symbol rate equal to the bit rate of each input data channel.

Abstract: Systems and method of compensating for transmission impairment are disclosed. One such method comprises: receiving an optical signal which has been distorted in the physical domain by an optical transmission channel; and propagating the distorted optical signal backward in the electronic domain in a corresponding virtual optical transmission channel.

Abstract: In one embodiment a system and method pertain to generating a pump from a received optical signal, inputting the generated pump into a phase-sensitive oscillator, and amplifying a carrier component of the pump to generate an optical carrier having the same phase and polarity of an optical carrier of the received optical signal.

Abstract: Systems and methods of polarization-time coding are disclosed. One method includes encoding information in orthogonal polarizations of light and correlated information in multiple time slots, and transmitting the information using the orthogonal polarizations in the time slots. Another method includes receiving a first input pair which specifies a first polarization state and a second input pair containing which specifies a second polarization state; transforming each input pair according to a matrix specifying a conjugate operation to produce four output pairs. The method further includes transmitting at a first time the first output pair using the first polarization state and the third output pair using the second polarization state. The method further includes transmitting at a second time the second output pair using the first polarization state and the fourth output pair using the second polarization state.

Abstract: Efficient systems, devices, apparatus and methods to generate, transmit and detect differentially encoded 8-level phase-modulated optical signals for spectrally efficient optical communication systems is invented. It includes an electrical encoder and an optical encoder for generation of differentially encoded 8-level phase-modulated optical signals and optical demodulators and balanced detectors for detection of the optical signals. The optical signals are transmitted through optical fiber links or air. The electrical encoder maps three independent data channels into three differentially-encoded data sequences. In the optical encoder, the encoded data sequences from the electrical encoder drive optical modulators to generate differentially-encoded 8-level phase modulated optical signals at a symbol rate equal to the bit rate of each input data channel.

Abstract: In one embodiment a communications system includes an RF receiver that receives a desired signal and the interference signal, a first phase modulator that receives the desired signal and the interference signal from the RF receiver and generates a resulting optical signal, a second phase modulator that generates a modulated optical signal relative to an inverse interference signal and transmits the modulated optical signal to the first phase modulator, and a detector that receives the resulting optical signal from the first phase modulator and detects the desired signal, wherein the resulting optical signal comprises a modulated optical signal generated by the first phase modulator relative to the desired signal and the interference signal received from the RF receiver and relative to the modulated optical signal received from the second phase modulator.

Abstract: A regenerator for restoring the originally encoded optical phase of a differential-phase-shift-keyed signal. In an embodiment, the regenerator simultaneously provides limiting amplification and reduces amplitude noise based on a phase-sensitive optical amplifier that combines a weak signal field of a degraded input data with a strong pump field supplied by a local oscillator in a nonlinear interferometer. The two fields interact through degenerate four-wave mixing, and optical energy is transferred from the pump to the signal and vice versa. The phase sensitive nature of the optical gain leads to amplification of a specific phase component of the signal, determined by the input pump-signal phase difference and the incident signal phase is restored to two distinct states, separated by 180° according to the original encoding. Simultaneously, gain saturation of the pump wave by the signal wave results in limiting amplification of the signal wave for removing signal amplitude noise.

Abstract: All optical regeneration methods and systems can be realized through an exponential amplifier and a limiting amplifier, which could be two independent devices (one piece of fiber with parametric amplification and a semiconductor optical amplifier operating at saturation state) or one single device (one piece of fiber). The signal quality and the extinction ratio after regeneration are significantly improved compared with the degraded incoming data using a parametric amplifier with the data signal to be regenerated as the pump. The regenerated data has an extinction ratio as high as 14 dB, an extinction ratio enhancement of approximately 5 dB and an approximately 5 dB negative power penalty. This regeneration schemes are format transparent (RZ and NRZ), and provide noise reduction both for bit 1's and bit 0's of the data sequence. The regeneration method and apparatus that just utilizes fibers has the additional capability of ultrafast response speed (several femtoseconds due to the Kerr effect).

Abstract: An apparatus of the invention includes a non-linear optical element (NLOE) and an optical frequency discriminator (OFD). The NLOE receives an optical data signal, and introduces chirp at the leading and trailing portions of the optical pulse(s) therein or induces chirp on a continuous wave (CW) optical source coupled to the NLOE. The OFD is coupled to receive the chirped signal, and uses this signal to generate an optical clock signal. The OFD discriminates frequency content associated with chirp to enhance the optical clock signal, and may also suppress non-chirp frequency content such as may be associated with an optical carrier signal or a continuous wave (CW) signal. Related systems and methods are also disclosed.

Abstract: Disclosed apparatuses include a return-to-zero (RZ) optical pulse generator, a non-return-to zero (NRZ) modulator, and a return-to-zero (RZ) transmitter. The apparatuses incorporate an electro-absorption modulator (EAM) and a controller that controls DC and AC voltages supplied to the EAM to provide the capability to vary its duty cycle. The apparatuses can also incorporate a phase modulator (PM) supplied with DC and AC voltages governed by the controller, to introduce frequency chirp into optical signals generated by the apparatuses. Elements such as the EAM and PM can be formed as an integrated unit on a substrate.

Abstract: An apparatus of the invention includes a non-linear optical element (NLOE) and an optical frequency discriminator (OFD). The NLOE receives an optical data signal, and introduces chirp at the leading and trailing portions of the optical pulse(s) therein or induces chirp on a continuous wave (CW) optical source coupled to the NLOE. The OFD is coupled to receive the chirped signal, and uses this signal to generate an optical clock signal. The OFD discriminates frequency content associated with chirp to enhance the optical clock signal, and may also suppress non-chirp frequency content such as may be associated with an optical carrier signal or a continuous wave (CW) signal. Related systems and methods are also disclosed.

Abstract: A broad area plasma lighting device in which a sealed gas envelope placed adjacent to a planar inductive coupling structure generates visible light. Representative planar inductive coupling structures include a planar spiral coil and a parallel conductor coupling structure. According to the invention, a parallel conductor coupling structure has two basic forms: separate parallel conductors each driven by its own generator/tuning circuit, or single conductor such as a flattened helix or series of square coils driven by one generator/tuning circuit. In addition, a plasma generating device having one or more parallel conductor inductive coupling structures is described. The resulting plasma generator can be used in such applications as plasma processing and inductive plasma lighting.

Abstract: The observation of self-sustained pulsation and transient self-pulsation in laser diodes at 1300 nm is described with the effects of optoelectronic feedback on the pulsations. Transient self-pulsation has a lifetime of a few minutes with frequencies up to 7 GHz. The linewidth of self-pulsation is on the order of 0.5 GHz. With optoelectronic feedback, the transient self-pulsation can be stabilized and enhanced. The center frequency of feedback-sustained pulsation is dependent on the passband of the bandpass filter in the feedback loop. The linewidth of feedback-sustained pulsation is significantly reduced to about 20 kHz. The optical spectra of the laser diodes exhibit coherence collapse at weak optoelectronic feedback. The feedback sustained pulsation can be frequency modulated. Applications of the feedback-sustained pulsation include subcarrier multiplexing optical networks.

Abstract: Plasma polymerized organic films deposited on a substrate exhibit broad bandwidth photoluminescence after excitation with blue, violet, or ultraviolet light. The photoluminescent properties of such organic films may be exploited by using such films as wavelength transformers for photovoltaic materials, as organic solid-state gain media, as process quality control tools, and as color-correcting coatings for fluorescent lamps.