SOA Cross-gain Modulation Research Articles

Realization of High Speed All-Optical Half Adder and Half Subtractor Using SOA Based Logic Gates

In this paper, the scheme of a single module for simultaneous operation of all-optical computing circuits, namely half adder and half subtractor, are realized using semiconductor optical amplifier (SOA) based logic gates. Optical XOR gate by employing a SOA based Mach-Zehnder interferometer (MZI) configuration is used to get the sum and difference outputs. A carry signal is generated using a SOA-four wave mixing (FWM) based AND gate, whereas, the borrow is generated by employing the SOA-cross gain modulation (XGM) effect. The obtained results confirm the feasibility of our configuration by proving the good level of quality factor i.e. ~5.5, 9.95 and 12.51 for sum/difference, carry and borrow, respectively at 0 dBm of input power.

Optical Cache Memory Peripheral Circuitry: Row and Column Address Selectors for Optical Static RAM Banks

We demonstrate WDM-enabled all-passive optical row and column address selector (RAS/CAS) circuits for use as optical static RAM (SRAM) bank peripherals in future optical cache memory implementations. We show that the introduction of the wavelength dimension in both the memory address and data word fields can lead to RAS and CAS architectures that rely exclusively on all-passive wavelength-selective configurations. An all-optical 2 × 4 RAS comprising a wavelength-selective filtering matrix (λ-matrix) and a wavelength-based CAS unit formed by a simple AWG element are demonstrated in proof-of-principle experiments at 10 Gb/s with error-free operation at 10 -9 BER value using two different types of WDM SRAM row Access Gate (AG): a cross-phase modulation SOA-MZI gate and a single SOA cross-gain modulation gate, with the first providing the higher performance compared to SOA module and the second offering lower power requirements between the two WDM AG. A chip-scale optical cache peripheral circuitry development path using Silicon-on-Insulator (SOI) ring resonators for the λ-matrix implementation is also presented and the proposed architecture is evaluated via physical layer simulations using SOAs as SRAM row AGs at 10 Gb/s for a 16×4 optical SRAM bank. Moreover, we discuss on possible improvements towards reducing insertion losses of the RAS/CAS modules in order to allow for increased block sizes. Finally, we provide a detailed analysis on the design and parameter specifications required for RAS and CAS block size scaling towards supporting higher-capacity optical SRAM banks.

Coherent-to-incoherent light conversion for optical correlators

The authors present a novel coherent-to amplified spontaneous emission (ASE) converter based on SOA's cross-gain modulation (XGM) in a counterpropagating configuration. Experimental characterizations of the ASE converter with bit-error rate (BER) measurements at 2.5 and 5 Gb/s are shown. The device capabilities are exploited in a delay lines optical recognizer at 2.5 Gb/s. Recognition is based on a coherent-to-incoherent light conversion followed by a fiber array correlation filter. Experimental evidence here reported shows performance improvement in comparison with a scheme which adopts a standard telecom source.