Single-mode Fabry-Perot Laser Diode Research Articles

High-Speed Switchable Dual-Passband Microwave Photonic Filter With Dual-Beam Injection in an SMFP-LD

In this paper, a high-speed switchable dual-passband microwave photonic filter (MPF) using a single mode Fabry-Perot laser diode (SMFP-LD) is proposed and experimentally demonstrated. Benefiting from the wavelength selective amplification in the SMFP-LD, the +1 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">st</sup> sideband of two external beams injected after phase modulation can be amplified in the gain spectrum of the SMFP-LD. Hence, an MPF with two tunable passbands is generated. The switching of the generated passbands is obtained through the switching signal of 1 Gbps applied to the modulator, which controls the power of one of the external beams. By properly setting the external beams’ injection parameters, the passbands of MPF can switch from single passband to no passband, single passband to dual passband, and one passband to another passband. In this experiment, the maximum center frequency and tuning range of the passbands is 45.0 GHz and 35.0 GHz, respectively. The out-of-band rejection ratio and 3 dB bandwidth of the proposed filter are 29.62 dB and 83 MHz, respectively.

Writing 10 Gb/s Data Bits With Addressing Using External Cavity-Based SMFP-LDs

Memory accessing is one of the challenging issues for utilizing the improvements in processor speed. Due to the rapid enhancement on processor speed compared to the memory accessing technique, the gap between the memory accessing and processor speed is rapidly widening. Hence, a new technique to address this issue needs to be devised. In this paper, we experimentally demonstrate the complete scheme of wavelength division multiplexing enabled memory write operation in the desired memory location using single mode Fabry–Perot laser diodes (SMFP-LDs). For a proof of concept, we demonstrate writing a stream of data bits at 10 Gb/s data rate in a memory unit that consists of four single bit set–reset (SR) latches with a unique address. The input data bits are stored in the respective latch of the memory bank in accordance with the address bit set along with a write instruction. A higher order of memory units with address decoding can be realized by increasing the higher order of decoder and the memory units. The observed optical domain waveforms at the respective nodes of each block, eye diagram, SNR, and bit error rate (BER) prove the verification of writing input data to the desired memory locations using SMFP-LDs. We observed an extinction ratio of more than 12 dB, no noise floor at the BER of 10−12, and a maximum power penalty of about 2.5 dB in the proposed scheme.

Optical Behavior Analysis of Negative Wavelength Detuning in SMFP-LD and Its Effect on Multi-RF Generation

Injection locking with positive wavelength detuning has been used for a long time for optical signal processing, signal generation, and computing. Recently a new technique, “injection locking with negative wavelength detuning,” has been introduced and has shown its potential on microwave generation. In this paper, we analyze optical behavior of negative injection locking and its impact on multi-RF generation using single-mode Fabry-Perot laser diode (SMFP-LD). SMFP-LD is composed of a commercial multi-mode FP-LD with a built-in external cavity. As compared to conventionally used positive detuning optical injection, the negative detuning optical injection (NOI) shows advantageous differences on the suppression of the dominant mode, side modes, bistability property, and the hysteresis width. The laws of free carrier motion in the laser cavity is leveraged to explain these phenomena. Based on the analysis, the NOI in the SMFP-LD has a distinct advantage for multi-RF generation and switching RF signals. In addition, the output performances of the generated RF signal such as linewidth, power-dependent frequency shifting, and signal-to-noise ratio (SNR) are investigated.

Microwave Frequency Generation, Switching, and Controlling Using Single-Mode FP-LDs

RF signal generation, switching, and reconfiguring are essential and important features for the rapidly developing microwave system, which are usually implemented using independent components or subsystems. In this paper, we propose and demonstrate an optical method to generate and switch the RF frequency at the stage of generation based on control input state using external cavity based single mode Fabry–Perot laser diode. The RF frequency generation, switching, and controlling are based on the principle of injection locking with negative and positive wavelength detuning. In the proposed scheme, a single external beam is simultaneously used to control RF switching as well as to generate RF signal through optical heterodyning of injection locked beams. This eliminates the necessity of two separate external beams to switch and generate RF signal. Based on the logic state of the input control beam, the frequency of the generated RF signal can be changed to another RF frequency within a group of predefined RF bands. In a proof-of-concept experiment, a 2-Gbps, 16-bit nonreturn-to-zero control signal is applied to switch the frequency of the generated RF signal. We obtain the minimum signal to noise power ratio of more than 23 dB, the maximum linewidth of 165 kHz, and rising and falling times of less than 40 ps associated with the RF switching. The tunable range, RF frequency, and RF power variation of the generated RF signals are also observed. Moreover, using random control signals, random sequences of RF frequencies can be generated using the same experimental and hardware setup. Such reconfigurability and flexibility of our system to generate several random RF signals from the same framework enables application of the proposed method in several fields such as secure communication, encryption, and military applications.

Injection With Negative Wavelength Detuning for Multispectrum Frequency Generation and Hopping Using SMFP-LD

We propose and demonstrate a novel method to generate multispectrum frequency and hopping from one frequency spectrum to another using a single external cavity based Fabry–Perot laser diode (FP-LD) subjected to a single optical injection with negative wavelength detuning. The external cavity based FP-LD has a single dominant mode, single-mode FP-LD (SMFP-LD), and hence the beating of the dominant mode and the injected beam, and the beating of the injected beam and the corresponding side mode of SMFP-LD are possible with a single optical injection. The generated frequency can be tuned to a wide range of GHz to several THz. Individual or simultaneous RF signals generation and hopping between microwave and millimeter wave spectrum are reported. The effect of the injected beam power on generating and hopping of RF frequency is analyzed in the case of negative wavelength detuning with the input beam injected on different modes of SMFP-LD. Also, the stability of beating wavelengths, power variations of beating wavelengths for an interval of 1 hour, and linewidth of RF signals are observed.

Nearly Degenerate Four-Wave Mixing in Single-Mode Fabry–Pérot Laser Diode Subject to Single Beam Optical Injection

In this paper, nearly degenerate four-wave mixing created by pump–probe structure with small frequency spacing and enough high power is demonstrated and discussed by introducing single optical beam into single-mode Fabry–Perot laser diode, in which the injected beam is called the probe wave, whose frequency detuning is controlled within ±50 GHz, and lasing resonance mode such as dominant mode or arbitrarily residual side mode is selected as the pump wave. In the case of dominant mode like the pump wave, conjugate signals around the pump–probe wave are easily observed for positive and negative probe detuning by judiciously tuning injected probe power. While external injection mode is moved towards the side mode selected as the pump wave, newly generated signals only occurred with small positive probe detuning. As the probe wave with positive frequency detuning is close to the pump wave, higher order conjugate signals are gradually grown. Under the condition of side mode as the pump wave, the strongly nonlinear mixing of the pump–probe wave also gives rise to new frequency signals on both sides of the dominant mode with enough high peak level. Against the change of correspondingly initial power and frequency detuning of the probe wave, outcome spectrum, output power, and conversion efficiency of conjugate signals are analyzed in detail, while dominant or one side mode is, respectively, selected as the pump wave.

Highly Nondegenerate Four-Wave Mixing in Single-Mode Fabry–Pérot Laser Diode Subject to Dual-Mode Injection

In this paper, highly nondegenerate four-wave mixing (NDFWM) resulting from external dual-mode injection (pump-probe structure) in the single-mode Fabry-Perot laser diode (SMFP-LD) is proposed and experimentally demonstrated. To cause the effective NDFWM process, both pump and probe beams with enough power levels should, respectively, be close to various resonance modes in the active region, whose detuning frequency can be discontinuously varied from more than 100 GHz to up to 800 GHz. Normalized conversion efficiency (NCE) and optical signal-to-noise ratio (OSNR) of newly generated conjugate signals are strongly dependent on external injection power, wavelength detuning, and detuning frequency. In addition, the NDFWM process exhibits injection probe power-related hysteresis behaviors, whereas the input power and wavelength for pump beam are, respectively, fixed at some special constants.

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 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-12</sup> are observed. The maximum power penalty is about 1.8 dB at BER of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-9</sup> .

All-optical exclusive-NOR and exclusive-OR logic gate based on multi-input injection locking in single mode Fabry–Pérot laser diode

All-optical logic gates are the basic components of all-optical signal processing and computing. Among all other logic gates, exclusive-OR (XOR) plays a significant role on optical computing, switching, and networking. We propose a novel and simple scheme for all-optical exclusive-NOR and XOR logic gates using single mode Fabry-Perot laser diode (SMFP-LD). The logic gates are based on the multi-input injection locking and supporting beam principle to suppress the intensity of the dominant mode of the SMFP-LD. The working principle of the proposed scheme is explained, and the experimental results are presented at the data rate of 10 Gbps input signals for the logic operations. We observed clear eye openings with an extinction ratio of about 12 dB and a rising/falling time of about 35 ps of the logic outputs. The demonstrated scheme can be used to implement all-optical computing and switching networks.

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-Perot 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-Perot 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-Perot 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.

All-Optical Wavelength Conversion by the Modulation of Self-Locking State of a Single-Mode FP-LD

A novel and quite simple all-optical wavelength converter using a single-mode Fabry-Pe?rot laser diode (SM FP-LD) is proposed. The working principle is explained and the experimental results at 10 Gb/s are demonstrated. The wavelength conversion is realized based on injection-locking and the modulation of self-locking state of the SM FP-LD by an external pump injection. The converted signals show about an 11-dB extinction ratio and a sidemode suppression ratio (SMSR) of 43 dB in static measurement. We measured the bit-error-rate (BER) performances and error-free conversions were observed. A power penalty of less than 1 dB at a BER of 10-9 was measured, for two different input wavelengths conversion.

All-optical flip-flop with high on-off contrast ratio using two injection-locked single-mode Fabry-Perot laser diodes

An all-optical flip-flop with inverted output is presented. The flip-flop is realized based on the optical bistability of an injection-locked single-mode Fabry-Perot laser diode (FP-LD). The operation principle is explained and experimental results are presented in this paper. The flip-flop with separate optical set and reset inputs had an on-off contrast ratio of over 35 dB.

Tunable single-mode Fabry-Perot laser diode using a built-in external cavity and its modulation characteristics

A tunable single-mode laser is obtained by using a weakly coupled cavity structure involved in a coaxially packaged Fabry-Perot laser diode. The cleaved end facet of the coupling fiber becomes an optical reflector and forms an external cavity with a laser facet. The single-mode oscillation condition is controlled and stabilized by tuning the operating temperature. The tuning range is about 10 nm with the side-mode suppression ratio of more than 27 dB when the temperature changes from 11.5 degrees C to 25 degrees C. Direct modulation characteristics were investigated, and our results show that a shorter external cavity can bear deeper modulation depth.

Linewidth reduction and wavelength tuning of an erbium-doped fiber laser by use of a single-mode-selected and side-mode-suppressed Fabry-Perot laser diode.

A single-mode and highly side-mode-suppressed 1.55-microm Fabry-Perot laser diode (FPLD) is achieved by feedback injection with an erbium-doped fiber laser (EDFL). For selection of the strongest longitudinal mode from the gain spectrum of the FPLD for lasing in the EDFL, the FPLD is operated at just below the threshold condition and is feedback injected by 0.02% of the EDFL output power. The lasing mode and center wavelength of the proposed single-mode FPLD source are decided by cross-correlated gain profiles of the EDFL and the FPLD; however, the effect of FPLD injection modes is found to be more pronounced. The optimized lasing linewidth (system limitation) and side-mode suppression ratio of 0.01 nm and > 49 dB are obtained, which are far better than those of a FPLD at free-running condition. The worst linewidths at 3- and 10-dB decay are observed to be at approximately 0.016 and 0.05 nm, respectively. Linear wavelength tuning of as much as 4.5 nm (from 1558.7 to 1563.2 nm) by adjustment of the temperature of the FPLD from 10 degrees C to 40 degrees C at just below threshold is reported. The wavelength-tuning slope is approximately 0.14 nm/degrees C under temperature accuracy of 0.1 degrees C.

A novel integrated micromachined tunable laser using polysilicon 3-D mirror

A prototype tunable laser of /spl sim/2 mm/spl times/1.5 mm size has been developed for wavelength-division-multiplexing (WDM) application. This device is an integrated micromachined polysilicon three-dimensional (3-D) mirror with a single-mode Fabry-Perot laser diode and an antireflection-coated optical fiber. The micromirror can be driven to move laterally by an electrostatic comb-drive that changes the external cavity length of laser diode enabling wavelength tuning. A wavelength-tunable range of 16 nm is obtained using a driving voltage within /spl plusmn/3 V at a bias voltage of 10 V.

Noise Analysis in Coherence-Multiplexed Optical Fiber Communication Systems

By exploiting the coherence properties of optical sources, many users can be multiplexed on to a single channel achieving a secure, asynchronous mode of transmission, free of central network control. In this paper an analysis of the impact of interference from unwanted users is described and limitations imposed by shot, phase, and partition noise on coherence multiplexed system performance employing LED, multimode laser diode, DFB, and single mode Fabry–Perot laser diode sources are considered and compared. The determination of the amount of delay required to compensate for system limitation imposed by phase noise arising due to mismatches between transmitter and receiver interferometers to achieve a 10−9BER and the impact of interferometric noise in the perfectly matched scenario are presented.