Uncooled DWDM transmission system using tunable laser sources with anti-mode-hop control protocol

We propose an uncooled DWDM system where errors from uncontrolled laser mode-hopping are avoided by using a control protocol based on monitoring SMSR. We describe a proof-of-principle demonstration of a novel uncooled 50GHz DWDM system. © 2011 IEEE.

Instability of the steady-state regime of generation in laser diodes with a broad gain spectrum

The laser-diode parameters at which the steady-state regime of generation becomes unstable are analyzed within the framework of the mode-locking model. The crucial role of the transverse inhomogeneity of the field, pumping intensity, and spectrum width in developing the instabilities of the steady-state regime of generation is demonstrated. The calculated values of the instability threshold are shown to be consistent with the experimental results. © 2008 Springer Science+Business Media, Inc.

Theoretical study of line narrowing in a sub-terahertz monolithic dual laser source with an integrated reflector

A monolithic design is proposed for low-noise sub-THz signal generation by integrating a reflector onto a dual laser source. The reflectivity and the position of such a reflector can be adjusted to obtain constructive feedback from the reflector to both lasers, thus causing a Vernier feedback effect. As a result, 10-fold line narrowing, the narrowing being limited by the resolution of the simulation, is predicted using a transmission line model. Finally, a simple control scheme using an electrical feedback loop to adjust laser biases is proposed to maintain the line narrowing performance. This line narrowing technique, comprising a passive integrated reflector, could allow the development of a low-cost, compact and energy-efficient solution for high-purity sub-THz signal generation. © The Institution of Engineering and Technology 2014.

Photonic crystal distributed feedback quantum cascade laser fabricated with holographic technique

Electrically pumped, edge-emitting, singlemode operation of a two-dimensional photonic crystal distributed feedback (PCDFB) quantum cascade laser emitting at similar to 7.8 mu m is demonstrated. The two-beam holographic technique combined with wet-etching process is successfully used to de. ne a square-lattice PCDFB structure on the top grating layer of the laser. This simple PC fabrication method may open exciting opportunities for the wide application of PCDFB lasers.

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.

Low-threshold-current and high-out-power 660 nm laser diodes with a p-GaAs current blocking layer for DVD-RAM/R

We investigate a new structure of high-power 660-nm AlGaInP laser diodes. In the structure, a p-GaAs layer is grown on the ridge waveguide serving as the current-blocking layer, and nonabsorbing windows are only fabricated near the cavity facets to increase the catastrophic-optical-damage level. Stable fundamental mode operation was achieved at up to 80 mW without kinks, and the maximum output power was 184 mW at 22 degrees C. The threshold current was 40 mA.

Ridge waveguide laser integrated with spot-size converter in a single step epitaxial for high coupling efficiency to single-mode fibres

A 1.55-mum laser diode integrated with a spot-size converter was fabricated in a single step epitaxial by using the conventional photolithography and chemical wet etching process. The device was constructed by a conventional ridge waveguide active layer and a larger passive ridge-waveguide layer. The threshold current was 40 mA together with high slope efficiency of 0.24 W/A. The beam divergence angles in the horizontal and vertical directions were as small as 12.0degrees x 15.0degrees, respectively, resulting in about 3.2-dB coupling losses with a cleaved optical fibre.

Electroabsorption-Modulated DFB laser Integrated.With dual-core spot-size converters

A 1.55-mu m single shallow ridge electroabsorptionmodulated distributed feedback laser that is monolithically integrated with a buried-ridge-stripe dual-core spot-size converter (SSC) at the input and output ports was fabricated by combining selective area growth, quantum-well intermixing, and dual-core integration techniques simultaneously. These devices exhibit a threshold current of 34 mA, a side mode suppression ratio of 38.0 dB, a 3-dB modulation bandwidth of 11.0 GHz, and a modulator extinction ratio of 25.0 dB dc. The output beam divergence angles of the SSC in the horizontal and vertical directions are as small as 7.3 degrees x 18 degrees, respectively, resulting in 3.2-dB coupling loss with a cleaved single-mode optical fiber.

High-power AlGaInP laser diodes with current-injection-free region near the laser facet

A high-power AlGaInP laser diode with current-injection-free region near the facet is successfully fabricated by metaorganic chemical vapor deposition (MOCVD) using the (100) direction n-GaAs substrates with a misorientation of 15 deg toward the (011) direction. The maximum continuous wave output power is about 90 mW for the traditional structure. In comparison, the maximum output power is enhanced by about 67%, and achieves 150 mW for LDs with current-infection-free regions. The fundamental transverse-mode operation is obtained up to 70 mW. Output characteristics at high temperatures are also improved greatly for an LD with a current-injection-free region, and the highest operation temperature is 70 C at 50 mW without kink. The threshold current is about 33 mA, the operation current and the slope efficiency at 100 mW are 120 mA and 0.9 mW/mA, respectively. The lasing wavelength is 658.4 nm at room-temperature 50 mW. (c) 2006 Society of Photo-Optical Instrumentation Engineers.

Wavelength tunable distributed Bragg reflector laser integrated with electro-absorption modulator by a combined method of selective area growth and quantum well intermixing - art. no. 68240N

Wavelength tunable electro-absorption modulated distributed Bragg reflector lasers (TEMLs) are promising light source in dense wavelength division multiplexing (DWDM) optical fiber communication system due to high modulation speed, small chirp, low drive voltage, compactness and fast wavelength tuning ability. Thus, increased the transmission capacity, the functionality and the flexibility are provided. Materials with bandgap difference as large as 250nm have been integrated on the same wafer by a combined technique of selective area growth (SAG) and quantum well intermixing (QWI), which supplies a flexible and controllable platform for the need of photonic integrated circuits (PIC). A TEML has been fabricated by this technique for the first time. The component has superior characteristics as following: threshold current of 37mA, output power of 3.5mW at 100mA injection and 0V modulator bias voltage, extinction ratio of more than 20 dB with modulator reverse voltage from 0V to 2V when coupled into a single mode fiber, and wavelength tuning range of 4.4nm covering 6 100-GHz WDM channels. A clearly open eye diagram is observed when the integrated EAM is driven with a 10-Gb/s electrical NRZ signal. A good transmission characteristic is exhibited with power penalties less than 2.2 dB at a bit error ratio (BER) of 10(-10) after 44.4 km standard fiber transmission.

cryptanalysis of the end-to-end security protocol for mobile communications with end-user identification/authentication

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