All-optical packet compression of variable length packets from 40 to 1500 B using a gated fiber loop

A scalable loop-based packet compression scheme capable of handling variable length Internet protocol packets, from 40 to 1500 B, is proposed and demonstrated. The technique uses per packet variable compression ratio to achieve fixed compressed output packet size independent of input packet size. This technique allows variable length packets to be stored in fixed delay optical buffers and has application to optical packet switching, optical multiplexing, and optical grooming. These results demonstrate the largest packet size compressed to date. Error-free compression and verification of 1500-B packets compression from 2.5 to 10 Gb/s is demonstrated with a measured power penalty of /spl sim/2.2 dB.     

Optical buffers for variable length packets

This letter addresses the problem of dimensioning fiber delay lines for optical buffers in a network scenario where packets are asynchronous and of variable length. The focus is placed on providing a simple analytical model to dimension the basic time unit of the fiber delay line, as the crucial parameter that determines the queueing performance     

Payload-envelope detection and label-detection integrated photonic circuit for asynchronous variable-length optical-packet switching with 40-gb/s RZ payloads and 10-gb/s NRZ labels

A photonic integrated circuit that performs 40-Gb/s payload-envelope detection (PED) and 10-Gb/s label detection for asynchronous variable-length optical-packet switching is demonstrated. The circuit consists of an InP photonic integrated device combined with electronic GaAs and InP devices on a carrier. Asynchronous variable-length optical packets with 40-Gb/s return-to-zero (RZ) payloads and 10-Gb/s non-RZ (NRZ) labels are processed by the circuit. The circuit outputs a PED electrical signal that represents the temporal location of the payload and a 10-Gb/s electrical signal representing the optical label. The optical label is detected error free. The PED signal has a rise/fall time of 3-ns and 150-ps jitter. The PED signal was also used to erase and rewrite the optical labels error free.     

Monolithically integrated 40-gb/s switchable wavelength converter

An all-optical switchable wavelength-converting module at 40 Gb/s line rate is demonstrated in a fully integrated InP chip. The device combines a semiconductor optical amplifier-based wavelength converter and a fast-tunable multifrequency laser. Sub-nanosecond switching among the eight channels of the integrated laser is shown, and error-free operation of the wavelength conversion process at 40 Gb/s for each wavelength is demonstrated. The applications of fast switching wavelength conversion for optical switching and packet routing are discussed.     

Monolithic demodulator for 40-gb/s DQPSK using a star coupler

A novel device that demodulates both quadratures of the optical differential quadrature phase-shift keying (DQPSK) format in a single interferometer by using a 4 /spl times/ 4 star coupler was demonstrated. Simultaneous measurements of both DQPSK quadratures at 42.7 Gb/s are also presented.     

All-optical 80-gb/s time-division demultiplexing using polarization-insensitive cross-phase modulation in photonic crystal fiber

We describe an all-optical 80-Gb/s time-division demultiplexer, which utilizes cross-phase modulation in a commercial photonic crystal fiber. Compared to back-to-back 10-Gb/s measurements, the demultiplexer achieves better than a 2.5-dB power penalty for all eight channels. More importantly, we demonstrate a novel scheme for polarization-insensitive operation, which uses only the birefringence of the fiber itself and proper alignment of the clock pulse polarization. Using this technique, the polarization sensitivity of the converted power is found to be less than 0.4 dB, allowing for error-free demultiplexing even while the data polarization state is scrambled.     

Heuristic performance model of optical buffers for variable length packets

Optical switching (optical packet switching, optical burst switching, and others) provides alternatives to the current switching in backbone networks. To switch optically, also packet buffering is to be done optically, by means of fiber delay lines (FDLs). Characteristic of the resulting optical buffer is the quantization of possible delays: Only delays equal to the length of one of the FDLs can be realized. An important design challenge is the optimization of the delay line lengths for minimal packet loss. To this end, we propose a heuristic based on two existing queueing models: one with quantization and one with impatience. Combined, these models yield an accurate performance modeling heuristic. A key advantage of this heuristic is that it translates the optical buffer problem into two well-known queueing problems, with accurate performance expressions available in the literature. This paper presents the heuristic in detail, together with several figures, comparing the heuristic’s output to existing approaches, validating its high accuracy.     

40-gb/s EA modulators with wide temperature operation and negative chirp

Broad bandwidth external modulators are widely used in optical fiber networks to avoid the chirp associated with the direct modulation of laser diode sources. For transmission application beyond 10 Gb/s, electroabsorption modulators (EAMs) offer many advantages such as low drive voltage, low chirp characteristics, small size, and added functionality through integration with a distributed feedback laser. In this letter, we present static and dynamic characterization of an EAM demonstrating the possibility to have with the same device uncooled operation at 40 Gb/s and negative chirp at low negative bias. These features are attractive for cost reduction in short link applications and for long-haul transmission. All the measurements are performed at 40 Gb/s from room temperature up to 60/spl deg/C demonstrating a negative chirp behavior for the stand-alone modulator over the entire temperature range.     

Dispersion-tolerant 10-gb/s duobinary system employing heterodyne detection and MLSE

We experimentally demonstrate a 10.7-Gb/s duobinary transmission system operating over a chromatic-dispersion range of /spl sim/12 000 ps/nm. Heterodyne detection and maximum-likelihood sequence estimation are employed to achieve this result.     

All-optical label and payload separator for a time-serial RZ-IM/IM scheme

We demonstrate an all-optical label and payload separator based on nonlinear optical signal processing with a semiconductor optical amplifier. The separator handles return-to-zero intensity modulated packets with high bandwidth efficiency utilization.     

All-optical label processor/erasure for label swapping of 12.5 Gbit/s spectrally separated bit-serial DPSK label and payload

A novel all-optical label processor/erasure for DPSK spectrally separated label and payload is demonstrated. Experimental results show the recognition of two different labels at 12.5 Gbit/s at distinct outputs, while the label is simultaneously erased allowing for a new label insertion. The low power and asynchronous label processor/erasure can be scaled to distinguish a larger number of labels, to operate at higher bit rate, and then can be potentially used in an optical label switching network.     

利用MZ-DI装置的40Gb/s RZ到NRZ全光码型变换

利用马赫-曾德尔延时干涉(MZ-DI)装置对40Gb/s的归零(RZ)码到非归零(NRZ)码的全光码型转换方案进行研究.利用通信软件模拟了40Gb/s的码型转换过程,实现稳定的不同占空比的RZ码到NRZ码的码型转换.当占空比约为0.3时,转换效果最佳.     

Modeling O/E characteristics of 40-gb/s InGaAs side-illuminated waveguide photodiode submodule for optical receivers

In this paper, the circuit models of a waveguide photodiode (WGPD) and its submodule were investigated, and the O/E characteristics of a WGPD submodule are examined. Test structures of the WGPD and WGPD submodule were fabricated and microwave return loss (S11) was measured and compared with simulated data to validate the circuit models. With the established submodule model, optical to electrical (O/E) characteristics were measured and compared with the modeled data to analyze the effects of model parameters on the submodule performance. Based on the results, it can be concluded that the suggested submodule model can explain the characteristics of the submodule performance. In addition, parasitic components that originated from the ribbon bonding block can crucially impact on the performance of WGPD submodule.     

Buffering management schemes for optical variable length packets under limited packet sorting

This paper studies several buffering strategies for optical packet switching (OPS) under limited packet sorting. Three schemes, which are able to sort newly arrived packets based on packet’s length as well as capability of finding the minimum buffer occupancy, are analyzed and compared. Results show that all three proposed schemes could improve OPS performance considerably in terms of probability of packet loss (PPL) and probability of information loss (PIL). In addition, the simulation results show that not all the newly arrived packets need to be sorted in order to obtain minimum packet loss probability. Since the amount of packets and thus the packet processing time is significant in OPS, it is possible that not all the packets can be processed using one of the buffering strategies. An important finding of this paper is that if only 10% of the packets are sorted, the PPL is comparable to the minimum packet loss value obtained when 100% of the packets are sorted.     

Serial dark soliton for 100-gb/s applications

We analyze the performance through numerical simulations of a new modulation format: serial dark soliton (SDS) for wide-area 100-Gb/s applications. We compare the performance of the SDS with conventional dark soliton, amplitude-modulation phase-shift keying (also known as duobinary), nonreturn-to-zero, and return-to-zero modulation formats, when subjected to typical wide-area-network impairments. We show that the SDS has a strong chromatic dispersion and polarization-mode-dispersion tolerance, while maintaining a compact spectrum suitable for strong filtering requirement in ultradense wavelength-division-multiplexing applications. The SDS can be generated using commercially available components for 40-Gb/s applications and is cost efficient when compared with other 100-Gb/s electrical-time-division-multiplexing systems.     

All-optical 40 Gbit/s XOR gate with dual ultrafast nonlinear interferometer

A novel XOR logic gate using dual cascaded ultrafast nonlinear interferometer elements based on semiconductor optical amplifiers is proposed and demonstrated at 40 Gbit/s. The gate is switched at the line rate rather than twice line rate, as in previously reported differential XOR gates.     

320-to-40-gb/s demultiplexing using a single SOA assisted by an optical filter

We demonstrate excellent all-optical demultiplexing of 40-Gb/s base-rate channels out of 160- and 320-Gb/s single polarization optical time-division-multiplexed data streams. The demultiplexer utilizes a semiconductor optical amplifier and an optical filter placed at the amplifier output. The center wavelength of the filter is blue-shifted from the wavelength of the clock signal, so that ultrafast chirp dynamics can be employed for optical switching. Error-free demultiplexing was achieved at very low optical switch powers: 3.5 mW (160-Gb/s data), 6.3 mW (320-Gb/s data), and 0.09 mW (40-GHz clock). The proposed demultiplexer has a simple structure and allows monolithic integration.     

Improvement of dispersion tolerance using phase-Modulated NRZ signals in 40-gb/s transmission systems

Compared with the conventional nonreturn-to-zero (NRZ), return-to-zero (RZ), carrier-suppressed return-to-zero, and chirped RZ signals by numerical simulation, a higher dispersion tolerance in the presence of fiber nonlinearities and amplifier noise has been obtained in this letter by using the phase-modulated NRZ signals. This scheme aims to improve resistance to residual dispersion by an adapted phase modulation at the transmitter.     

A 1.25-gb/s burst-mode receiver for GPON applications

This paper presents a 1.25-Gb/s burst-mode receiver (BMRx) for upstream transmission over gigabit passive optical networks (G-PONs). The dc-coupled receiver uses a unique arrangement of three limiting amplifiers to convert the bursty input signal to a current mode logic output signal while rejecting the dc offset from a preceding transimpedance amplifier. Peak detectors extract a decision threshold from a sequence of 12 successive nonreturn-to-zero (NRZ) 1's and 12 successive NRZ 0's received at the beginning of each packet. Automatic compensation of the remaining offsets of the BMRx is performed digitally via digital-to-analog converters. The chip was designed in a 0.35-/spl mu/m SiGe BiCMOS process. The receiver contains an APD with a gain of 6 and a transimpedance amplifier and shows a sensitivity of -32.8 dBm and a dynamic range of 23.8 dB. A sensitivity penalty of 2.2 dB is incurred when a packet with average optical power of -9 dBm precedes the packet under consideration, the guard time between the packets being 25.6 ns. The BMRx includes activity detection circuitry, capable of quickly detecting average optical levels as low as -35.5 dBm. The performed measurements prove that the receiver meets the G-PON physical media dependent layer specification defined in ITU-T Recommendation G.984.2.     

A 20-GHz phase-locked loop for 40-gb/s serializing transmitter in 0.13-/spl mu/m CMOS

A 20-GHz phase-locked loop with 4.9 ps/sub pp//0.65 ps/sub rms/ jitter and -113.5 dBc/Hz phase noise at 10-MHz offset is presented. A half-duty sampled-feedforward loop filter that simply replaces the resistor with a switch and an inverter suppresses the reference spur down to -44.0 dBc. A design iteration procedure is outlined that minimizes the phase noise of a negative-g/sub m/ oscillator with a coupled microstrip resonator. Static frequency dividers made of pulsed latches operate faster than those made of flip-flops and achieve near 2:1 frequency range. The phase-locked loop fabricated in a 0.13-/spl mu/m CMOS operates from 17.6 to 19.4GHz and dissipates 480mW.