A Novel Two-Section Tunable Discrete Mode Fabry-PÉrot Laser Exhibiting Nanosecond Wavelength Switching

A novel widely tunable laser diode is proposed and demonstrated. Mode selection occurs by etching perturbing slots into the laser ridge. A two-section device is realized with different slot patterns in each section allowing Vernier tuning. The laser operates at 1.3 mum and achieves a maximum output power of 10 mW. A discontinuous tuning range of 30 nm was achieved with a side mode suppression greater than 30 dB. Wavelength switching times of approximately 1.5 ns between a number of wavelength channels separated by 7 nm have been demonstrated.     

Enhanced Modulation Bandwidth of a Fabry–PÉrot Semiconductor Laser Subject to Light Injection From Another Fabry–PÉrot Laser

Variations in optical spectrum and modulation bandwidth of a modulated Fabry-Perot (FP) semiconductor laser subject to the external light injection from another FP Laser is investigated in this paper. Optimal wavelength matching conditions for two FP lasers are discussed. A series of experiments show that two FP lasers should have a central wavelength overlapping and a mode spacing difference of several gigahertz. Under these conditions both the magnitude and phase frequency responses can be improved significantly.     

1.25-Gb/s Operation of a Spectrum-Sliced Fabry–PÉrot Laser Diode With Intensity Noise Suppression by a Second Fabry–PÉrot Laser Diode

We propose a low-cost solution for the intensity noise suppression in the spectrum-sliced Fabry-Perot laser diode (F-P LD), which is achieved by placing an F-P LD at the receiver region. The F-P LD at the receiver region provides the intensity noise suppression of about 10 dB as well as the increase of the received optical power for the spectrum-sliced optical signal. The Q-factor is improved about 5.9 at a data rate of 1.25 Gb/s. As a result, we successfully demonstrate 10-km error-free transmission at 1.25-Gb/s signal with a transmission penalty of less than 0.5 dB. It is also found that the low spectrum-sliced power of -22 dBm achieves the relative intensity noise level of -112.5 dB/Hz, which is almost independent of the operation current.     

Tunable Dual-Wavelength Fiber Laser Using Optical-Injection Fabry–PÉrot Laser

In this investigation, we propose and experimentally demonstrate a dual-wavelength fiber laser based on a self-injected Fabry–PÉrot laser diode and an erbium-doped fiber. The dual-wavelength tuning range is 39.49 nm, from 1526.27 to 1565.76 nm, and the mode spacing of the dual-wavelength can be tuned from 1.32 to 39.49 nm. In addition, the output power difference of the dual-wavelength can be controlled and smaller than 1 dB.      

Temperature-Insensitive Micro Fabry–PÉrot Strain Sensor Fabricated by Chemically Etching Er-Doped Fiber

Micro extrinsic Fabry–PÉrot interferometric (MEFPI) sensors are fabricated by chemically etching Er-doped fibers with mixed hydrochloric (HCl) and hydrofluoric (HF) acid and fusion splicing. Compared with MEFPI sensors fabricated by etched single-mode fibers, the sensor performance is greatly improved by the chemical reaction between HCl acid and doped ${hbox {Er}}_{2}hbox{O}_{3}$ . A maximum visibility of $sim$ 24 dB is obtained, comparable to that of MEFPI sensors fabricated by excimer lasers. Our MEFPI sensor has high mechanical strength as the etching rate difference between fiber core and cladding is enlarged. Preliminary results indicate that this kind of sensor is insensitive to temperature while highly sensitive to strain, with sensitivities of $sim$0.65 $hbox{pm}/^{circ}hbox{C}$ and $sim$3.15 $hbox{pm}/muvarepsilon$ , respectively.      

Effects of In-Band Crosstalk in Wavelength-Locked Fabry–PÉrot Laser-Diode-Based WDM PONs

We investigated the impact of in-band crosstalk on the system's performance in wavelength-locked Fabry-Perot laser-diode (FP-LD)-based wavelength-division-multiplexed passive optical networks (WDM PONs). As expected, wavelength-locked FP-LD, which was injected by using an incoherent broadband light source, was more tolerant to in-band crosstalk than distributed-feedback (DFB) laser diode. A 1-dB power penalty in the wavelength-locked FP-LD-based PON system was observed when the crosstalk-to-signal ratio was ~-9 dB. We also compared the measured power penalties with the calculated power penalties. It has been shown that the in-band crosstalk-induced power penalty in wavelength-locked FP-LD-based WDM PON could be estimated properly by taking into account both effects of power addition and signal-crosstalk beat noise.     

Measurement of Facet Reflectivity Through Reflection Gain in Fabry–PÉrot Laser Diode

We propose a simple and useful method to measure the facet reflectivity in a Fabry-Perot laser diode (LD). The new measurement method does not require information on LD parameters such as threshold current or optical spectrum. The measurement is based on a simple formula that describes the relationship of facet reflectivity and reflection gain with launching the probe beam of a narrow spectral width.     

Single and Multiwavelength All-Optical Clock Recovery Using Fabry–PÉrot Semiconductor Optical Amplifier

We experimentally demonstrate an all-optical clock recovery scheme for the return-to-zero data with single- and multiwavelength. This scheme is mainly based on clock-like pulse generation from an active filter with a multiquantum-well Fabry–PÉrot semiconductor optical amplifier and amplitude-equalization with self-nonlinear polarization switching. We obtain stable and low jitter optical clock signals in single and dual channels using this scheme, which has some distinct advantages including easy integration, free preamplification, convenient tuning, good tolerance to long “0s” data, and greater tolerance to the stability of the input wavelength.      

Multiple Dual-Wavelengths Erbium-Doped Fiber Ring Laser Using a Polarization-Maintaining Fabry–PÉrot Filter

A multiple dual-wavelengths erbium-doped fiber laser is demonstrated. It is designed by using a narrowband polarization-maintaining Fabry–PÉrot filter in a ring cavity. More than 30 power equalized dual-wavelengths are achieved in a 10-nm range. The switchability from multiple dual-wavelengths to normal multiple wavelengths laser is also demonstrated experimentally.      

A WDM-PON Employing Fabry–PÉrot Laser Diodes Without a Seed Light Injection

We propose and demonstrate a wavelength-division-multiplexed passive optical network by employing double-contact Fabry-Perot laser diodes (F-P LDs) without a seed light injection. To avoid the high mode partition noise at low frequency, we use a binary phase-shift keying as a modulation format at a low relative intensity noise window. An error-free transmission is achieved by compensating a lasing envelope shift due to temperature variation with the double-contact F-P LD.     

Fabry–PÉrot Cavity Based on a Suspended-Core Fiber for Strain and Temperature Measurement

A fiber-optic Fabry–PÉrot sensing structure based on the utilization of a suspended-core fiber is presented. The interferometric structure is formed when a small length of the suspended-core fiber is spliced to the end of a standard single-mode fiber. The interfering waves are generated by the refractive-index mismatches between the two fibers in the splice region and at the end of the suspended-core fiber. Thermal and strain responses of two different sensing heads associated with suspended-core fibers with three and four holes are characterized.      

A Simple and Color-Free WDM-Passive Optical Network Using Spectrum-Sliced Fabry–PÉrot Laser Diodes

We propose and demonstrate a simple and color-free wavelength-division-multiplexing passive optical network (WDM-PON) using spectrum-sliced Fabry-Perot laser diodes (F-P LDs). Due to its low front facet reflectivity (~0.1%), the F-P LD shows a broadband lasing spectrum and reduced mode partition noise. By utilizing multiple peaks that are separated by the free-spectral range of the cyclic arrayed waveguide gratings, the 16-channel WDM-PON is successfully demonstrated at 155 Mb/s.     

Temperature-Dependent Saturation Characteristics of Injection Seeded Fabry–PÉrot Laser Diodes/Reflective Optical Amplifiers

In this paper, the temperature dependence of the gain and saturation power of injection seeded Fabry–Perot laser diodes/reflective semiconductor optical amplifiers are analyzed theoretically and experimentally. For a constant gain, the saturation power increases with the ambient temperature. This dependency explains the observed variation in relative intensity noise versus injection power, as a function of temperature.      

Fourier Transform White-Light Interferometry for the Measurement of Fiber-Optic Extrinsic Fabry–PÉrot Interferometric Sensors

A Fourier transform white-light interferometry for the absolute measurement of fiber-optic extrinsic Fabry-Perot interferometric sensors is presented. The continuous test shows the variation is plusmn0.3 mum when measuring a cavity length of 2300 mum. By combining with an average calculation, the variation of the measured results is only plusmn10 nm.     

Cavity Length Independent Continuous Repetition Rate Tuning of a Self-Seeded Gain-Switched Fabry–PÉrot Laser

We propose a novel method that allows continuous repetition rate tuning of a self-seeded gain-switched Fabry-Perot laser without the need for change in cavity length. This is achieved by employing a linearly chirped fiber Bragg grating with a large dispersion parameter. The dispersed pulses overlap to produce a continuous-wave-like feedback into the gain-switched laser cavity. By using the proposed experimental setup, we demonstrate pulses portraying sidemode suppression ratios of at least 30 dB and widths of about 30 ps over the entire repetition rate tuning range of 2.5-10 GHz.     

Sulfur Hexafluoride-Filled Extrinsic Fabry–PÉrot Interferometric Fiber-Optic Sensors for Partial Discharge Detection in Transformers

This letter presents a side-hole fiber-based extrinsic Fabry–PÉrot interferometric (EFPI) sensor whose cavity was filled with sulfur hexafluoride (SF$_{6}$) for in situ power transformer partial discharge detection. The Fabry–PÉrot cavity was formed by a polished thin diaphragm and a cleaved side-hole fiber that were thermally fused onto a fused silica ferrule. The cavity was first vacuumed and then inflated with 300-kPa SF$_{6}$ through the fiber side holes to increase its resistance to electric stress. Experimental results show that the sensor filled with SF$_{6}$ was able to withstand electric stress of at least 10 kV/mm (ac root-mean-square value) in transformer oil, three times larger than that of a traditional air-filled EFPI sensor.      

High-Power Single-Longitudinal-Mode Fiber Laser With a Ring Fabry–PÉrot Resonator and a Saturable Absorber

We demonstrated a high-power single-longitudinal-mode (SLM) all-fiber laser. In the cavity, a fiber Bragg grating is used to select the appropriate wavelength at 1565 nm, and a fiber ring is incorporated to act as a Fabry-Perot resonator, which greatly reduces the longitudinal-mode density. Meanwhile, an unpumped erbium-doped fiber serves as a saturable absorber to ensure the SLM operation. Finally, a high-power SLM fiber laser producing as high as 867-mW output power has been experimentally demonstrated.     

A Hollow-Core Photonic Crystal Fiber Cavity Based Multiplexed Fabry–PÉrot Interferometric Strain Sensor System

A hollow-core photonic crystal fiber Fabry-Perot interferometric (HC-PCF-FPI) strain sensing system is proposed and demonstrated. The sensing system has an excellent multiplexing capability owing to the wide free-spectral range of the HC-PCF-FPI structure. Moreover, with a simple fast Fourier transform demodulation method, the proposed strain sensing system could be potentially applied in structural health monitoring.     

Single-Longitudinal-Mode Erbium-Doped Fiber Ring Laser Based on High Finesse Fiber Bragg Grating Fabry–PÉrot Etalon

We present a simple and stable single-longitudinal-mode (SLM) erbium-doped fiber laser. It consists of an apodized fiber Bragg grating (FBG) and a high finesse FBG-based Fabry-Perot (FP) etalon in the ring cavity. The apodized FBG acts as a wavelength discriminative component selecting a few oscillation modes while the FP etalon serves as narrow bandwidth bandpass filter to further discriminate and select SLM efficiently. Stable SLM laser output at 1.55 m with linewidth about 2.5 kHz is acquired. Furthermore, continuous wavelength tuning over 8 nm is achieved by simultaneously applying strain to the FBG and the FP etalon.     

Fiber-Optic Distributed Sensor Based on Hybrid Raman and Brillouin Scattering Employing Multiwavelength Fabry–PÉrot Lasers

We propose the use of standard multiwavelength Fabry–PÉrot (FP) lasers for distributed strain and temperature measurement in hybrid Raman- and Brillouin-based fiber-optic sensors. The multiple longitudinal modes of FP lasers allow for accurate spontaneous Raman scattering measurement and for simultaneous high-sensitivity coherent detection of the Brillouin frequency shift parameter for all longitudinal modes. Experimental results confirm great performance improvement in simultaneous strain and temperature measurement using a single optical fiber.