Rate adjustable NRZ-DPSK modulation scheme with a fixed interferometer

Minch, J.; Townsend, Daniel J.; Gervais, David R.

doi:10.1109/leosst.2005.1527984

Cited by 8 publications

(7 citation statements)

References 7 publications

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“…Typically, adjacent bits are differentially encoded with a time-separation τ d of one symbol duration or a bit period, τ bit , but this can generally be extended to an integer number n of symbol periods, i.e., τ d = nτ bit . This can provide some flexibility in implementing simplified multi-rate and multi-channel receivers (see, e.g., [134][135][136]), a subject discussed further in section 5.2.…”

Section: Differential-phase-shift-keying (Dpsk)mentioning

confidence: 99%

“…Variable duty cycle techniques can also be used to simplify multi-rate DPSK receivers [10,134] discussed in the next section. With a reconfigurable DI (see section 5.2.4) that can adjust the delay to accommodate the bit rate, a single filter design can be used to achieve nearly-quantum-limited receiver sensitivity at all rates.…”

Section: Optimized Multi-rate Transceiversmentioning

confidence: 99%

“…With a reconfigurable DI (see section 5.2.4) that can adjust the delay to accommodate the bit rate, a single filter design can be used to achieve nearly-quantum-limited receiver sensitivity at all rates. Alternatively, for harmonically related data rates, a fixed DI sized to the lowest rate can be used [134] along with appropriate differential precoding. In this case, the same DI can be used to simultaneously demodulate multiple-rate WDM-DPSK signals (see section 5.2.3), providing both rate-flexibility and WDM scalability [136].…”

Section: Optimized Multi-rate Transceiversmentioning

confidence: 99%

“…At the output coupler, the two overlapping field components interfere constructively or destructively depending on the relative phase of the differentially encoded bits, with the resulting output power proportional to the product of the two fields, being directed to the first or second output port. For complete interference, the incident fields need to have the same amplitude, and a delay that is a positive integer multiple n of the bit-period τ bit [134,135], i.e.,…”

Section: Differential Phase Shift Keying (Dpsk)mentioning

confidence: 99%

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Laser communication transmitter and receiver design

Caplan

2007

J Optic Comm Rep

118

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Free-space laser communication systems have the potential to provide flexible, high-speed connectivity suitable for long-haul intersatellite and deep-space links. For these applications, power-efficient transmitter and receiver designs are essential for cost-effective implementation. State-of-the-art designs can leverage many of the recent advances in optical communication technologies that have led to global wideband fiber-optic networks with multiple Tbit/s capacities. While spectral efficiency has long been a key design parameter in the telecommunications industry, the many THz of excess channel bandwidth in the optical regime can be used to improve receiver sensitivities where photon efficiency is a design driver. Furthermore, the combination of excess bandwidth and average-power-limited optical transmitters has led to a new paradigm in transmitter and receiver design that can extend optimized performance of a single receiver to accommodate multiple data rates. This paper discusses state-of-the-art optical transmitter and receiver designs that are particularly well suited for average-power-limited photon-starved links where channel bandwidth is readily available. For comparison, relatively simple direct-detection systems used in short terrestrial or fiber optic links are discussed, but emphasis is placed on mature high-performance photon-efficient systems and commercially available technologies suitable for operation in space. The fundamental characteristics of optical sources, modulators, amplifiers, detectors, and associated noise sources are reviewed along with some of the unique properties that distinguish laser communication systems and components from their RF counterparts. Also addressed is the interplay between modulation format, transmitter waveform, and receiver design, as well as practical tradeoffs and implementation considerations that arise from using various technologies.

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Section: Differential-phase-shift-keying (Dpsk)mentioning

confidence: 99%

Section: Optimized Multi-rate Transceiversmentioning

confidence: 99%

Section: Optimized Multi-rate Transceiversmentioning

confidence: 99%

Section: Differential Phase Shift Keying (Dpsk)mentioning

confidence: 99%

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Laser communication transmitter and receiver design

Caplan

2007

J Optic Comm Rep

118

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“…While their simplified approach enables ITU compatibility, the ~14% mismatch leads to a waveform-dependent penalty of ~1.2 dB for 33% RZ pulse-shapes, further reducing the sensitivity benefit of DPSK [16]. To avoid mismatch penalty, the interferometer delay (τ d = 1/FSR) must be an integer multiple n of the bit-period τ bit , i.e., τ d = nτ bit (see e.g., [17]). Here, we use this relation and the DI's periodic transfer function to demonstrate simultaneous demodulation of 2.5 Gbit/s and 5 Gbit/s WDM-DPSK signals using a single DI.…”

mentioning

confidence: 99%

High-Sensitivity Demodulation of Multiple-Data-Rate WDM-DPSK Signals using a Single Interferometer

Caplan

Stevens

Carney

2007

OFC/NFOEC 2007 - 2007 Conference on Optical Fiber Communication and the National Fiber Optic Engineers Conference

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We demonstrate simultaneous reception of multiple-rate wavelength-division-multiplexed optical-DPSK signals using a single interferometer. The demodulation approach provides rate-flexibility and scalability, enabling penalty-free performance and compliance with existing channel-rate and channel-spacing standards. 1Introduction Optical differential-phase-shift-keying (DPSK) modulation has received considerable attention by the free-space optical (FSO) communications community and the telecom industry for its increased sensitivity over commonly used on-off-keying [1-6], and reduced peak-to-average power ratio which mitigates nonlinear effects in fiber-optic applications. These benefits have led to many Tbit/s long-haul fiber-optic experiments using hundreds of WDM-DPSK channels [7-10]. The advantages of DPSK come at the expense of increased complexity, requiring a phase modulator in the transmitter (TX), and an optical delay-line interferometer (DI) and balanced detection in the receiver (RX) to derive maximum benefit. Of these elements, the DI is the most technically challenging and the least mature. For good performance, the arms of the DI must be precisely fabricated to within a small fraction of a bit-period, and they must be stable to a small fraction of a wavelength, requiring careful thermo-mechanical packaging and/or stabilization electronics [11][12][13][14], adding to size, weight, power, and cost.Miyamoto and coauthors [15] demonstrated interferometer sharing by converting 42.7 Gbit/s WDM-DPSK channels to WDM-duobinary channels on the 100 GHz ITU grid using a 50 GHz free-spectral-range (FSR) DI. Their innovative DPSK RX has advantages in dispersion-limited fiber links, but has inherent sensitivity penalties of 3 dB due to single-ended DPSK reception and an additional penalty due to the rate-to-FSR mismatch. While their simplified approach enables ITU compatibility, the ~14% mismatch leads to a waveform-dependent penalty of ~1.2 dB for 33% RZ pulse-shapes, further reducing the sensitivity benefit of DPSK [16]. To avoid mismatch penalty, the interferometer delay (τ d = 1/FSR) must be an integer multiple n of the bit-period τ bit , i.e., τ d = nτ bit (see e.g., [17]). Here, we use this relation and the DI's periodic transfer function to demonstrate simultaneous demodulation of 2.5 Gbit/s and 5 Gbit/s WDM-DPSK signals using a single DI. This technique can be scaled to higher rates and channel count, and operate within existing standards without waveform-dependent penalties. Description of the multi-rate multi-channel DPSK approachPenalty-free multi-channel DPSK reception can be achieved by leveraging the DI's periodic transfer function (Fig. 1a), and constraining the received wavelength spacing (Δν ch ), which enables simultaneous demodulation of all channels (λ's). WDM channel separation is achieved via optical demultiplexing after the DI [15,18,19] (Fig. 1b). dB Normalized Frequency Offset, Δf/FSR cos 2 () sin 2 ()

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