Abstract: In an embodiment, an optical communication system includes an optical transmitter and an optical discriminator. The optical transmitter is configured to emit a frequency modulated signal having a bit rate frequency and a frequency excursion between 20% and 80% of the bit rate frequency. The optical discriminator is configured to convert the frequency modulated signal to a substantially amplitude modulated signal and includes a delay line interferometer (DLI). The DLI includes an input, an output, a first optical path coupling optical signals from the input to the output and a second optical path coupling optical signals from the input to the output. The first and second optical paths have different lengths.

Abstract: An optical apparatus, comprising a polarization beam splitter (PBS) comprising a birefringent crystal having a front-end and a back-end, and an optical rotator positioned on the back-end of the birefringent crystal. Included is an optical apparatus comprising a PBS comprising a birefringent crystal and an optical rotator, wherein the PBS is configured to receive a multiplexed optical signal comprising a first polarized optical signal and a second polarized optical signal, wherein the second polarized optical signal is orthogonal to the first polarized optical signal, separate the first polarized optical signal from the second polarized optical signal using the birefringent crystal, and rotate the second polarized optical signal using the optical rotator such that the rotated second polarized optical signal is parallel to the first polarized optical signal. The PBS may further comprise only one lens, wherein the lens is positioned on the front-end of the birefringent crystal.

Abstract: A method comprising coupling a circuit to an opto-electronic package via an anisotropic conductive film (ACF), wherein the opto-electronic package is configured to communicate electrical signals via the coupling at a maximum frequency of about 10 gigahertz (GHz) to about 40 GHz. An apparatus comprising, an opto-electronic package comprising a plurality of first electrodes, and a circuit comprising a plurality of second electrodes, wherein at least one of the first electrodes is coupled to at least one of the second electrodes via an ACF, and wherein the opto-electronic package is configured to communicate electrical signals via the coupling at a maximum frequency of about 10 GHz to about 40 GHz.

Abstract: Thermal chirp compensation in a chirp managed laser. In one example embodiment, a laser package including a laser and an optical spectrum reshaper configured to convert frequency modulated optical signals from the laser into an amplitude modulated optical signals is provided. A thermal chirp compensation device is in communication with the laser package and a laser driver. The thermal chirp compensation device includes means for generating bias condition and temperature specific thermal chirp compensation signals that each corresponds to a predetermined level of thermal chirp that is induced in the laser by operating the laser at a particular bias condition and temperature.

Abstract: An optical transmitter with chirp control includes an input polarizer having an input that receives an optical signal. The input polarizer polarizes the optical signal along an input polarization axis. A Mach-Zehnder modulator includes an optical input that is coupled to an output of the input polarizer and an electrical input that receives a modulation signal. The Mach-Zehnder modulator modulates the optical signal with the modulation signal. The input polarization axis of the input polarizer is chosen to achieve a desired chirp of the modulated optical signal. An output polarizer is coupled to the output of the Mach-Zehnder modulator. The output polarizer polarizes the modulated optical signal along a desired output polarization axis that combines TE and TM mode polarizations.

Abstract: A phase-shift keyed signal demodulator and method for demodulating is disclosed. An example demodulator includes N filters that receive inputs from a splitter and include transmission functions offset from one another. N pairs of photodiodes receive the transmitted and reflected beams from each filter and a decoder converts the outputs of the pairs of photodiodes to one or more data symbols.

Abstract: A phase-shift keyed signal demodulator is disclosed including a filter positioned to receive an input beam, a first photodiode positioned to receive light reflected from the filter, and a second photodiode positioned to receive light transmitted through the filter. A difference between outputs of the first and second photodiodes is interpreted to determine a data value encoded in the input beam. In another embodiment N filters receive inputs from a splitter and include transmission functions offset from one another. N pairs of photo diodes receive the transmitted and reflected beams from each filter and a decoder converts the outputs of the pairs of photodiodes to one or more data symbols.

Abstract: A phase-shift keyed signal demodulator and method for demodulating is disclosed. An example demodulator includes N filters that receive inputs from a splitter and include transmission functions offset from one another. N pairs of photodiodes receive the transmitted and reflected beams from each filter and a decoder converts the outputs of the pairs of photodiodes to one or more data symbols.

Abstract: Thermal chirp compensation in a chirp managed laser. In one example embodiment, a laser package including a laser and an optical spectrum reshaper configured to convert frequency modulated optical signals from the laser into an amplitude modulated optical signals is provided. A thermal chirp compensation device is in communication with the laser package and a laser driver. The thermal chirp compensation device includes means for generating bias condition and temperature specific thermal chirp compensation signals that each corresponds to a predetermined level of thermal chirp that is induced in the laser by operating the laser at a particular bias condition and temperature.

Abstract: Thermal chirp compensation in a chirp managed laser. In one example embodiment, a method for thermal chirp compensation in a chirp managed laser (CML) includes several acts. First, a first bias condition and temperature is selected. Next, a first thermal chirp compensation signal is generated. Then, the laser is driven by biasing a first input drive signal with the first thermal chirp compensation signal. Next, a second bias condition and temperature is selected. Then, a second thermal chirp compensation signal is generated. Finally, the laser is driven by biasing a second input drive signal with the second thermal chirp compensation signal.

Abstract: An optical transmitter is disclosed wherein a signal processor receives a data stream and outputs a drive signal for a laser, where the drive signal encodes each bit of the data stream according to the values of adjacent bits effective to compensate for spreading of bits within the fiber. The output of the laser is input to an optical spectrum reshaper that outputs a signal having an enhanced extinction ratio.

Abstract: The frequency chirp modulation response of a directly modulated laser is described using a small signal model that depends on slow chirp amplitude s and slow chirp time constant ?s. The small signal model can be used to derive an inverse response for designing slow chirp compensation means. Slow chirp compensation means include electrical compensation, optical compensation, or both. Slow chirp electrical compensation can be implemented with an LR filter or other RF circuit coupled to a direct modulation source (e.g., a laser driver) and the directly modulated laser. Slow chirp optical compensation can be implemented with an optical spectrum reshaper having a rounded top and relatively large slope (e.g., 1.5-3 dB/GHz). The inverse response can be designed to under-compensate, to produce a flat response, or to over-compensate.

Abstract: A method for generating D-N-PSK optical signals is disclosed wherein a laser is modulated to generate optical signal pairs including phase modulated and fixed phase portions, the phase modulated portions having a frequency encoding one or more data symbols and the fixed phase portion having a carrier frequency and a phase corresponding to the immediately preceding phase modulated portion. The output of the laser is passed through an optical spectrum reshaper having a transmission function chosen to attenuate a plurality of the phase modulated portions relative to the fixed phase portions. The phase modulated portions may have N frequency levels located on either side of the carrier frequency. One of the N frequency levels may be equal to the carrier frequency.

Abstract: A phase-shift keyed signal demodulator is disclosed including a filter positioned to receive an input beam, a first photodiode positioned to receive light reflected from the filter, and a second photodiode positioned to receive light transmitted through the filter. A difference between outputs of the first and second photodiodes is interpreted to determine a data value encoded in the input beam. In another embodiment N filters receive inputs from a splitter and include transmission functions offset from one another. N pairs of photo diodes receive the transmitted and reflected beams from each filter and a decoder converts the outputs of the pairs of photodiodes to one or more data symbols.

Abstract: An optical transmitter is disclosed for transmitting a signal along a dispersive medium to a receiver. The optical transmitter generates adiabatically chirped profile having an initial pulse width and frequency excursion chosen such that high frequency data sequences include one bits that interfere destructively at a middle point of an intervening zero bit upon arrival at the receiver.

Abstract: Thermal chirp compensation in a chirp managed laser. In one example embodiment, a method for thermal chirp compensation in a chirp managed laser (CML) includes several acts. First, a first bias condition and temperature is selected. Next, a first thermal chirp compensation signal is generated. Then, the laser is driven by biasing a first input drive signal with the first thermal chirp compensation signal. Next, a second bias condition and temperature is selected. Then, a second thermal chirp compensation signal is generated. Finally, the laser is driven by biasing a second input drive signal with the second thermal chirp compensation signal.

Abstract: An optical transmitter is discloses having a gain section and a phase section. The phase section is modulated to generate a frequency modulated signal encoding data. The frequency modulated signal is transmitted through an optical spectrum reshaper operable to convert it into a frequency and amplitude modulated signal. In some embodiments, a driving circuit is coupled to the phase and gain sections is configured to simultaneously modulate both the phase and gain sections such that the first signal is both frequency and amplitude modulated.

Abstract: An optical transmitter comprising: an optical source modulated with an input digital data signal so as to generate a first, frequency-modulated digital signal; and an amplitude modulator, modulated with the logical inverse of the input digital data signal, for receiving the first, frequency-modulated signal and generating a second, amplitude-modulated and frequency-modulated digital signal; wherein the optical source and the amplitude modulator are each configured so as to produce positive transient chirp.

Abstract: An optical transmitter is disclosed wherein a signal processor receives a data stream and outputs a drive signal for a laser, where the drive signal encodes each bit of the data stream according to the values of adjacent bits effective to compensate for spreading of bits within the fiber. The output of the laser is input to an optical spectrum reshaper that outputs a signal having an enhanced extinction ratio.

Abstract: An optical transmitter is disclosed including an optical signal source generating a frequency modulated signal encoding data. An optical spectrum reshaper is positioned to receive the frequency modulated signal and converts the frequency modulated signal into a reshaped signal having increased amplitude modulation relative to the frequency modulated signal. A third-order dispersive element is positioned to receive the reshaped signal and is adapted to impose third-order dispersion on the reshaped signal to generate a compensated signal having third-order dispersion effective to compensate for second-order dispersion caused by an optical fiber positioned between the optical transmitter and a receiver.