Comparison of two kinds of active layers for high-power narrow-stripe distributed feedback laser diodes

Usually GaAs/AlGaAs is utilized as an active layer material in laser diodes operating in the spectral range of 800 850 nm. In this work, in addition to a traditional unstrained GaAs/AlGaAs distributed feedback (DFB) laser diode, a compressively strained InGaAlAs/AlGaAs DFB laser diode is numerically investigated in characteristic. The simulation results show that the compressively strained DFB laser diode has a lower transparency carrier density, higher gain, lower Auger recombination rate, and higher stimulated recombination rate, which lead to better a device performance, than the traditional unstrained GaAs/AlGaAs DFB laser diode.

High-Power Distributed Feedback Laser Diodes Emitting at 820nm

By etching a second-order grating directly into the Al-free optical waveguide region of a ridgewaveguide（RW） AlGaInAs/AlGaAs distributed feedback（DFB） laser diode,a front facet output power of 30mW is obtained at about 820nm with a single longitudinal mode. The Al-free grating surface permits the re-growth of a high-quality cladding layer that yields excellent device performance. The threshold current of these laser diodes is 57mA,and the slope efficiency is about 0.32mW/mA.

1.55-mu m ridge DFB laser integrated with a buried-ridge-stripe dual-core spot-size converter by quantum-well intermixing

A ridge distributed feedback laser monolithically integrated with a buried-ridge-stripe spot-size converter operating at 1.55 mu m was successfully fabricated by means of low-energy ion implantation quantum-well intermixing and dual-core technologies. The passive waveguide was optically combined with a laterally exponentially tapered active core to control the mode size. The devices emit in a single transverse and single longitudinal mode with a sidemode suppression ratio of 38.0 dB. The threshold current was 25 mA. The beam divergence angles in the horizontal and vertical directions were as small as 8.0 degrees x 12.6 degrees, respectively, resulting in 3.0-dB coupling loss with a cleaved single-mode optical fiber.

1.55-mu m Ridge DFB laser and electroabsorption modulator integrated with buried-ridge-stripe dual-waveguide spot-size converter output

A 1.55-mu m ridge distributed feedback laser and electroabsorption modulator monolithically integrated with a buried-ridge-stripe dual-waveguide spot-size converter (SSC) at the output port for low-loss coupling to a cleaved single-mode optical fiber was fabricated by means of selective area growth, quantum-well intermixing, and dual-core technologies. These devices exhibit threshold current of 28 mA, 3-dB modulation bandwidth of 12.0 GHz, modulator extinction ratios of 25.0-dB dc. The output beam divergence angles of the SSC in the horizontal and vertical directions are as small as 8.0 degrees x 12.6 degrees, respectively, resulting in 3.2-dB coupling loss with a cleaved single-mode optical fiber.

Distributed feedback multipeak laser emission in Rhodamine 6G doped organic-inorganic hybrids

Organic-inorganic hybrid materials were prepared from an ureasil precursor (ureapropyltriethoxysilane designated as UPTES) and acrylic acid modified zirconium (IV) n-propoxide. Thin films containing rhodamine 6G (Rh6G) were prepared by spin-coating on glass substrates with different Zr:Si molar ratios (Zr:Si = 75:25, 50:50 and 25:75). Refractive index, thickness, number of propagating modes and attenuation coefficient were measured at 543.5, 632.8 and 1550 nm wavelengths by the prism coupling technique. Distributed feedback (DFB) laser effect was observed and studied as a function of films thickness and refractive index.

Boolean logic device done with DFB laser diode

We present simulation results on how power output-input characteristic Instability in Distributed FeedBack -DFB semiconductor laser diode SLA can be employed to implemented Boolean logic device. Two configurations of DFB Laser diode under external optical injection, either in the transmission or in the reflective mode of operation, is used to implement different Optical Logic Cells (OLCs), called the Q- and the P-Device OLCs. The external optical injection correspond to two inputs data plus a cw control signal that allows to choose the Boolean logic function to be implement. DFB laser diode parameters are choosing to obtain an output-input characteristic with the values desired. The desired values are mainly the on-off contrast and switching power, conforming shape of hysteretic cycle. Two DFB lasers in cascade, one working in transmission operation and the other one in reflective operation, allows designing an inputoutput characteristic based on the same respond of a self-electrooptic effect device is obtained. Input power for a bit'T' is 35 uW(70uW) and a bit "0" is zero for all the Boolean function to be execute. Device control signal range to choose the logic function is 0-140 uW (280 uW). Q-device (P-device)

Electrical and optical coupling in an electroabsorption modulator integrated with a DFB laser

Electrical and optical coupling in an electroabsorption (EA) modulator integrated with a distributed feedback (DFB) laser have been investigated. The integrated device is treated as a three-port optoelectronic device with two electrical ports and one optical output port. The scattering parameters of this three-port device have been measured in the designed experiment. The measured results indicate that there exists the electrical coupling between the DFB laser and EA modulator of the integrated light source whenever the current applied to the laser section is below or above the threshold current, and the optical coupling will have stronger influence on the frequency responses than the electrical coupling when the bias current is above the threshold. A small-signal equivalent circuit model for the integrated device is established considering both the electrical and internal optical coupling. Experiments show that the equivalent circuit model is reasonable and the determined element values are correct. Based on the measurement and modeling, the influences of the electrical and optical coupling on the high-frequency responses are investigated and the effective measure to eliminate the additional modulation in the DFB laser are discussed.

Self-aligned current aperture in native oxidized AlInAs buried heterostructure InGaAsP/InP distributed feedback laser

A InGaAsP/InP self-aligned, native oxidized buried heterostructure (BH) distributed feedback (DFB) laser is proposed. It is as easy to process as the ridge waveguide DFB laser and has superior performance. The current aperture can be easily controlled without selective regrowth. The laser exhibits a low threshold of 5.0 mA with 36 dB side mode suppression ratio at the emission wavelength of 1.562 mu m. It emits in a single lobe with full width at half maximum angles of 33.6 degrees and 42.6 degrees for the lateral and vertical fields, respectively. Its beam is more circular than that of the as-grown BH laser because the lower refractive index of oxide compared to the as-grown layer and results in a larger lateral optical confinement. Its characteristic temperature (T-0) is 50 K at room temperature but increases in value at the higher temperature range. (C) 2000 American Institute of Physics. [S0003-6951(00)00812-3].

All-Optical Clock Recovery for 20 Gb/s Using an Amplified Feedback DFB Laser

We report all optical clock recovery based on a monolithic integrated four-section amplified feedback semiconductor laser (AFL), with the different sections integrated based on the quantum well intermixing (QWI) technique. The beat frequency of an AFL is continuously tunable in the range of 19.8-26.3 GHz with an extinction ratio above 8 dB, and the 3-dB linewidth is close to 3 MHz. All-optical clock recovery for 20 Gb/s was demonstrated experimentally using the AFL, with a time jitter of 123.9 fs. Degraded signal clock recovery was also successfully demonstrated using both the dispersion and polarization mode dispersion (PMD) degraded signals separately.

All-optical logic gates with 1550nm Fabry-Perot and distributed feedback semiconductor laser amplifiers

The optical bistability occurring in laser diode amplifiers is used to design an all-optical logic gate capable to provide the whole set of logic functions. The structure of the reported logic gate is based on two connected 1550nm laser amplifiers (Fabry-Perot and distributed feedback laser amplifiers).

Organic distributed feedback laser to monitor solvent extraction upon thermal annealing in solution-processed polymer films

Solution-processed polymer films are used in multiple technological applications. The presence of residual solvent in the film, as a consequence of the preparation method, affects the material properties, so films are typically subjected to post-deposition thermal annealing treatments aiming at its elimination. Monitoring the amount of solvent eliminated as a function of the annealing parameters is important to design a proper treatment to ensure complete solvent elimination, crucial to obtain reproducible and stable material properties and therefore, device performance. Here we demonstrate, for the first time to our knowledge, the use of an organic distributed feedback (DFB) laser to monitor with high precision the amount of solvent extracted from a spin-coated polymer film as a function of the thermal annealing time. The polymer film of interest, polystyrene in the present work, is doped with a small amount of a laser dye as to constitute the active layer of the laser device and deposited over a reusable DFB resonator. It is shown that solvent elimination translates into shifts in the DFB laser wavelength, as a consequence of changes in film thickness and refractive index. The proposed method is expected to be applicable to other types of annealing treatments, polymer-solvent combinations or film deposition methods, thus constituting a valuable tool to accurately control the quality and reproducibility of solution-processed polymer thin films.

A novel tunable all-optical incoherent negative-tap fiber-optic transversal filter based on a DFB laser diode and fiber Bragg grating

We demonstrate experimentally a novel and simple tunable all-optical incoherent negative-tap fiber-optic transversal filter based on a distribution feedback laser diode and high reflection fiber Bragg gratings (FBGs). In this filter, variable time delay is provided by cascaded high reflection fiber Bragg gratings (FBGs), and the tuning of the filter is realized by tuning different FBG to match the fixed carrier wavelength, or adjusting the carrier wavelength to fit different FBG. The incoherent negative tapping is realized by using the carrier depletion effect in a distribution feedback laser diode.

Narrow-band generation in random distributed feedback fiber laser

Narrow-band emission of spectral width down to ∼0.05 nm linewidth is achieved in the random distributed feedback fiber laser employing narrow-band fiber Bragg grating or fiber Fabry-Perot interferometer filters. The observed line-width is ∼10 times less than line-width of other demonstrated up to date random distributed feedback fiber lasers. The random DFB laser with Fabry-Perot interferometer filter provides simultaneously multi-wavelength and narrow-band (within each line) generation with possibility of further wavelength tuning. © 2013 Optical Society of America.

Modeling of spectral and statistical properties of a random distributed feedback fiber laser

For the first time we report full numerical NLSE-based modeling of generation properties of random distributed feedback fiber laser based on Rayleigh scattering. The model which takes into account the random backscattering via its average strength only describes well power and spectral properties of random DFB fiber lasers. The influence of dispersion and nonlinearity on spectral and statistical properties is investigated. The evidence of non-gaussian intensity statistics is found. © 2013 Optical Society of America.

NLSE-based model of a random distributed feedback fiber laser

In this work we propose a NLSE-based model of power and spectral properties of the random distributed feedback (DFB) fiber laser. The model is based on coupled set of non-linear Schrödinger equations for pump and Stokes waves with the distributed feedback due to Rayleigh scattering. The model considers random backscattering via its average strength, i.e. we assume that the feedback is incoherent. In addition, this allows us to speed up simulations sufficiently (up to several orders of magnitude). We found that the model of the incoherent feedback predicts the smooth and narrow (comparing with the gain spectral profile) generation spectrum in the random DFB fiber laser. The model allows one to optimize the random laser generation spectrum width varying the dispersion and nonlinearity values: we found, that the high dispersion and low nonlinearity results in narrower spectrum that could be interpreted as four-wave mixing between different spectral components in the quasi-mode-less spectrum of the random laser under study could play an important role in the spectrum formation. Note that the physical mechanism of the random DFB fiber laser formation and broadening is not identified yet. We investigate temporal and statistical properties of the random DFB fiber laser dynamics. Interestingly, we found that the intensity statistics is not Gaussian. The intensity auto-correlation function also reveals that correlations do exist. The possibility to optimize the system parameters to enhance the observed intrinsic spectral correlations to further potentially achieved pulsed (mode-locked) operation of the mode-less random distributed feedback fiber laser is discussed.