An Integrated 40 Gbit/s Optical Costas Receiver

Abstract

In this paper, a highly-integrated widely-tunable optical homodyne receiver is reported with 40 Gbaud/s data rate. By using photonic and electronic integration, the receiver is realized within a size of 10 10 , and the system is very robust and resistive to environmental changes. An integrated photonic coherent receiver circuit is demonstrated with 35 GHz photodetector bandwidth, and the integrated local oscillator (LO) laser covers a 40 nm range. The electronic IC (EIC) has a working frequency up to 50 GHz. The feedback loop is carefully analyzed and designed, and the experimental results show loop bandwidth, which matches the design. The hold-in range is measured to be . The phase noise of the transmitting laser has been cloned to the LO laser quite well, and both the linewidth measurement and phase noise measurement show no observable cross talk between binary phase shift keying (BPSK) data and the optical phase-locked loop (OPLL). Error free ( ) is achieved up to 35 Gbit/s. The system consumes 3 Watts of power.

An All-Digital Optical Phase-Locked Loop Suitable for Satellite Downlinks

“…Thus, the Viterbi-Viterbi algorithm is applied synchronously according to the system SR. Furthermore, the advent of integrated photonics [33] and higher sample rate systems would make integrating both systems (OPLL and DSP) possible. For example, the VCO could be replaced by a direct digital synthesizer (DDS) that would digitally generate the microwave carrier.…”

Optical carrier extraction from carrier-less phase modulated optical signals

“…which is the same as P 1;QPSK ð LO Þ given by (4). In this case with k equal to = ffiffi ffi 2 p , the phases of E 2 ð0; LO Þ, E 2 ð=2; LO Þ, E 2 ð; LO Þ, and E 2 ð3=2; LO Þ are aligned at the same value when LO ¼ AE=4, that is, the phase data of the QPSK signal is erased.…”

“…Because carrier is suppressed in most of practical modulation formats used in coherent systems such as binary or quaternary phase shift keying (BPSK or QPSK) and quadrature amplitude modulation (QAM), extraction of carrier from such carrier-less signals is particularly important. In addition to the Costas-loop scheme [4,5] traditionally used in wireless systems, several schemes of optical carrier extraction from carrier-suppressed signals have been recently proposed. In [6], all-optical carrier extraction by a fiber-based phase sensitive oscillator pumped by amplified BPSK signals was demonstrated.…”

“…This approach requires neither high-speed electrical signal processing used in the Costas-loop method [4,5] and in [7] nor large optical powers that are needed in the all-optical methods. In this Letter we describe the principles and details of the proposed carrier extraction method.…”

Z-domain modeling methodology for homodyne digital optical phase-locked loop

“…The reason is the structure of homodyne OPLL is different from the structure of traditional PLL [22,23,24,25]. Up to now, only s-domain modeling method of homodyne OPLL is reported [26,27]. But for homodyne digital OPLL with digital loop filter, signals in digital loop filter are discrete type and not suitable to be modelled by s-domain modeling method.…”