We propose a novel photonic technique for microwave frequency measurement based on transversal microwave filters with high resolution. Two parallel microwave filters with sine and cosine frequency responses are obtained by cross gain modulation in a single semiconductor optical amplifier, which introduces two different frequency responses to achieve an amplitude comparison function. We also demonstrate a proof-of-concept experiment. The measurement error is less than ±0.04 GHz for the first band range of 0–3.45 GHz and less than ±0.03 GHz for the second band range of 3.45–5.8 GHz. Our scheme is found to be capable of being extended for larger frequency range measurements using a shorter fiber length.
A scheme for all-optical NOR logic gate is proposed based on injection-locking effect in a semiconductor laser. In this scheme, signal light injection into the laser will cause frequency shift of laser modes, as a result, the probe light into the laser can be switched between injection-locked and unlocked status, and its output power will be modulated. Theoretical analysis for this scheme is carried out by using a model to describe the dynamics of the injection-locked laser. By numerical simulation, the influence of laser bias current, laser length, injected signal power and signal frequency on the output performance of NOR logic gate is quantitatively analyzed.
HAN Liu-yan, ZHANG Han-yi, and GUO Yi-li State Key Laboratory on Integrated Optoelectronics, National Laboratory for Information Science and Technology, De- partment of Electronic Engineering, Tsinghua University, Beijing 100084, China
This paper proposes and simulates a novel all-optical error-bit amplitude monitor based on cross-gain modulation and four-wave mixing in cascaded semiconductor optical amplifiers （SOAs）, which function as logic NOT and logic AND, respectively. The proposed scheme is successfully simulated for 40 Gb/s return-to-zero （RZ） signal with different duty cycles. In the first stage, the SOA is followed by a detuning filter to accelerate the gain recovery as well as improve the extinction ratio. A clock probe signal is used to avoid the edge pulse-pairs in the output waveform. Among these RZ formats, 33% RZ format is preferred to obtain the largest eye opening. The normalized error amplitude, defined as error bit amplitude over the standard mark amplitude, has a dynamic range from 0.1 to 0.65 for all RZ formats. The simulations show small input power dynamic range because of the nonlinear gain variation in the first stage. This scheme is competent for nonreturn-to-zero format at 10Gb/s as well.
