Tran Quoc Hoai

Demonstration of All-Optical nand Gate Using Single-Mode Fabry–Pérot Laser Diode

A novel, simple, and universal all-optical NAND gate using single-mode Fabry-Pérot laser diode (SMFP-LD) is demonstrated. The basic operating principle of the proposed NAND gate is the modulation of the dominant lasing mode of SMFP-LD by the injection of external beams. The dominant lasing mode gain is suppressed only when both input beams are high. As SMFP-LD is used to demonstrate the logic function, no additional beam is required as needed in the multimode Fabry-Pérot laser diode (MMFP-LD) schemes. The operating principle is explained and the experimental results are presented at 10 Gb/s input data. The logic function is realized with a clear eye opening and an extinction ratio of 14.6 dB with a rising and falling time of 38.3 and 67.1 ps, respectively.

A Simple Controlled All-Optical on/off Switch Using Gain Modulation in Single Mode FP-LD

A novel and simple controlled all-optical on/off switch using the gain modulation in a single-mode Fabry-Pérot laser diode (SMFP-LD) is demonstrated. The working principle of the proposed on/off switch is explained and the experimental results with 10 Gb/s data signal are presented. The 10 Gb/s data signal is switched on and off with a 350 MHz control signal. The extinction ratio of 15.6 dB is observed at the output port with a 2 dB power difference between the control signal and input signal. We measured the rising and falling time of the switch output as 48 and 59 ps, respectively.

Short-pulse controlled optical switch using external cavity based single mode Fabry-Pérot laser diode.

We propose and demonstrate a novel scheme for short pulse controlled all-optical switch using external cavity based single mode Fabry- Pérot laser diode (SMFP-LD). The proposed scheme consists of control unit and switching unit as two essential blocks. The basic principle of the proposed scheme is the optical bistability property of SMFP-LD for the control unit and the suppression of the dominant beam of SMFP-LD with injection locking for the switching unit. We also present the analysis of hysteresis width and rising/falling time with change in wavelength detuning which helps to find the optimum wavelength detuning value and power of light beams at different stages of the proposed scheme that gives wide input dynamic power range, high ON/OFF contrast ratio, and low rising/falling time. Input data of 10 Gb/s Non Return to Zero (NRZ) signal is switched at output ports depending upon the control signal generated by the control unit, which comprises of optical SR latch. Output waveforms, clear eye diagrams with extinction ratio of about 11 dB, rising/falling time of about 30 ps and 40 ps, and bit error rate (BER) are measured to validate proposed scheme. No noise floor is observed at output ports up to BER of 10-(12) and the maximum power penalty recorded is about 1.7 dB at a BER of 10-(9) which shows good performance of the proposed short pulse controlled optical switch using SMFP-LDs.

Analysis of Hysteresis Width on Optical Bistability for the Realization of Optical SR Flip-Flop Using SMFP-LDs With Simultaneous Inverted and Non-Inverted Outputs

The width of hysteresis in optical bistability plays an important role on latching operation. The injected input optical power and wavelength detuning in single mode Fabry-Perot laser diode (SMFP-LD) are two parameters that can impact the width of hysteresis in bistability of dominant mode and injected mode. In this paper, we analyze the effect of wavelength detuning on width of the hysteresis loop, the dynamic power range for optical bistability, and the rising-falling time of output waveform. With this analysis, optical Set Reset flip-flop with simultaneous inverted and non-inverted output at the data rate of 8.5 Gb/s are obtained using SMFP-LDs. The principle is based on the optical bistability phenomena during injection-locking of the Fabry-Perot laser diode. The set and reset pulses are maintained in low power of about -14 and -6 dBm for the power effective configuration. The contrast ratios of more than 20 dB with simultaneous non-inverted and inverted output Q and Q are observed. Clear output spectrum domain results, waveforms, eye diagram with extinction ratio of more than 12 dB, a rising/falling time of about 40 ps, and bit error rate (BER) measurement without noise floor up to 10 -12 are observed. The maximum power penalty is about 1.8 dB at BER of 10 -9.

Optical bistability in side-mode injection locked dual-mode Fabry-Pérot laser diode

In this paper, optical bistability characteristics are demonstrated experimentally based on a dual-mode laser system comprising a multi-mode Fabry-Perot laser diode (MMFP-LD) and a built-in feedback cavity formed by a fiber facet. The results show that two lasing modes with frequency separation of ∼0.58 THz and comparable peak powers can be achieved by judicious adjustment of the bias current and the operating temperature of the laser chip, which has a peak fluctuation of less than ∼1 dBm over a measurement period of one hour. A combination of appropriate external injection power and wavelength detuning can result in remarkable optical bistability in two oscillation modes, in which the resulting contrast ratio between the unlocked and locked states can be up to 30 dB, and the corresponding hysteresis loop width can be changed by controlling the side-mode injection power and the wavelength detuning.

Tunable Two-Color Lasing Emission Based on Fabry-Pérot Laser Diode Combined With External Cavity Feedback

In this paper, two-color lasing emission is experimentally demonstrated by employing a multimode Fabry-Pérot laser diode (MMFP-LD) associated with external cavity of two tunable filters and an erbium-doped fiber amplification (EDFA), whose difference frequency is quasi-continuously tunable from several hundred GHz to more than 2 THz. The obtained side-mode suppression ratio (SMSR) in the output spectrum is around ~20 dB, and the modulation depth of simulated beat signal converted by two emission modes rapidly decayed as increasing the frequency separation. In addition, optical behaviors induced by mode competition and four-wave mixing are observed and discussed, while the difference frequency was shortened to GHz regime.

All-optical logic gates (NAND and AND) based on multi-injection in single mode Fabry-Perot Laser

All-optical NAND and AND gate using single mode Fabry-Perot Laser diode (SMFP-LD) is demonstrated. The operating principle is based on the intensity modulation of SMFP-LD with combined input power of the logic gates.

Simultaneous inverted and non-inverted outputs all-optical flip-flop using Fabry-Perot laser diodes

An all-optical flip-flop using Fabry-Perot laser diode (FP-LD) is presented. The flip-flop is realized based on the bi-stability and gain modulation of injection-locked FP-LD. The flip-flop generates non-inverted and inverted outputs simultaneously. Non-inverted output shows 22 dB extinction ratio and inverted output shows 17 dB extinction ratio.

Optical S-R latch demonstration using injection-locked single-mode FP-LD

An optical S-R latch is demonstrated using two injection locked single-mode (SM) Fabry-Perot laser diode (FP-LD). The S-R latch is based on the bi-stability and injection-locking properties of FP-LD. The latch performs simultaneous inverted and non-inverted outputs in set and reset states. The switching time was about 90 ps.