Novel real-time homodyne coherent receiver using a feed-forward based carrier extraction scheme for phase modulated signals

Abstract

Abstract:We report a novel real-time homodyne coherent receiver based on a DPSK optical-electrical-optical (OEO) regenerator used to extract a carrier from carrier-less phase modulated signals based on feed-forward based modulation stripping. The performance of this non-DSP based coherent receiver was evaluated for 10.66Gbit/s BPSK signals. Selfhomodyne coherent detection and homodyne detection with an injectionlocked local oscillator laser was demonstrated. The performance was evaluated by measuring the electrical signal-to-noise (SNR) and recording the eye diagrams. Using injection-locking for the LO improves the performance and enables homodyne detection with optical injection-locking to operate with carrier-less BPSK signals without the need for polarization multiplexed pilot-tones.

Stabilization of self-coherent OFDM with injection locked laser

“…The locking range of the optical injection locking mechanism can be in the order of GHz, much larger than the ~MHz linewidth of typical distributed feedback (DFB) lasers, which enables low phase error performance and robust operation at high symbol rates. This is a noticeable implementation advantage of OIL against alternative synchronization schemes such as optical phase lock loops (OPLLs), which has made them particular attractive for a number of recent demonstrations in phase sensitive amplification [9] and coherent detection [10]. Indeed, traditional OPLL circuits made from commercial off-the-shelf (COTS) fiber pigtailed components have large feedback delays limiting the obtainable loop bandwidth and setting restrictions on the summed laser linewidth of the transmitter (master) and the local oscillator (slave).…”

Optical carrier extraction from carrier-less phase modulated optical signals

“…In [6], all-optical carrier extraction by a fiber-based phase sensitive oscillator pumped by amplified BPSK signals was demonstrated. In [7], feed-forward carrier extraction using opto-electro-optical modulation stripping together with injection locking of a laser diode (LD) was proposed. Low-speed electrical signal processing combined with all-optical modulation stripping by the parametric process in a nonlinear fiber was used for carrier extraction from high baud rate PSK signals in [8].…”

“…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.…”

60 Gbit/s, 64 QAM LD-based injection-locked coherent heterodyne transmission over 160 km with a spectral efficiency of 9 bit/s/Hz

“…For data, some phase synchronization schemes have already been developed with software [2,3] or hardware circuits [4,5]. Among them, an injectionlocking scheme is a very interesting way to realize low phase noise carrier synchronization with a simple receiver configuration [6].…”