Distributed Bragg Reflector Laser Array Research Articles

24‐wavelength distributed Bragg reflector laser array with surface gratings

A small footprint diode laser array of 24 individually addressable distributed Bragg reflector lasers is presented. Third-order gratings etched into the surface of an AlGaAs vertical waveguide structure act as Bragg reflectors. The ridge waveguides have an 87 µm-wide spacing and the emission wavelengths are spread on a 0.5 nm-wide grid around a centre wavelength of 905 nm. All 24 lasers on the array emit single mode with side mode suppression ratios > 50 dB and output powers >17 mW at 40 mA pump current.

10 Gbps transmission of electroabsorption modulators integrated with a 4-channel distributed Bragg reflector laser array

10 Gbps data transmission was demonstrated with electroabsorption modulators integrated with a 4-channel wavelength division multiplexing transmitter composed of distributed Bragg reflector (DBR) lasers. A selective area growth technique was employed for the control of bandgap energy in the gain, modulator and passive sections. Then the laser and modulator stripes were fabricated by a buried heterostructure process. The DBR lasers showed uniform threshold currents between 5 and 10 mA, while the slope efficiency was around 0.11 W A−1. By controlling the DBR currents, a 4-channel transmitter was achieved for the channel spacing of 100 GHz (0.8 nm). The electroabsorption modulator showed clear eye openings under 10 Gbps non-return-to-zero modulation. It allowed 10 Gbps error-free operation over a 25 km long single-mode fiber.

Waveguide distributed Bragg reflector laser arrays in erbium doped glass made by dry Ag film ion exchange

We demonstrate a distributed Bragg reflector (DBR) waveguide laser array by using an Ag film ion-exchange technique. We achieve an output power of 11 mW at 1540 nm for a coupled pump power of 145 mW, with a threshold of 60 mW and slope efficiency of 13%. The thin film ion exchange produces the highest index change possible at the surface, due to the ion exchange technique. Hence a wide array of wavelengths can be implemented in a single chip. We demonstrate a lasing wavelength range of 2.1 nm (1548.6 to 1550.7 nm) in an array with a single grating. Since the index change due to our process is large, we can fine tune the wavelengths of the array to fall on International Telecommunication Union (ITU) grid wavelengths by annealing. We demonstrate fine tuning of the wavelength for a channel from 1540.2 to 1540 nm, ITU specified wavelength, by annealing.

Monolithically integrated multiwavelength sampled grating DBR lasers for dense WDM applications

For accurate control of the channel spacing in fabricating multiwavelength laser arrays or discrete multicolor lasers, we proposed a novel approach that exploits sampled grating distributed Bragg reflector (DBR) mirrors to vary the laser wave length across the wafer. This approach can realize a set of lasers with a wavelength spacing that meets the ITU recommendations for dense wavelength-division multiplexing systems and a wavelength range that can cover up to 40 nm or more. The wavelength variation across an array is achieved by changing the sampling periods of the DBR mirrors from laser to laser. The accuracy on the channel spacing of sampled grating DBR laser arrays was shown to be the same as that of conventional distributed feedback or DBR laser arrays, but their wavelengths can be better controlled for the gratings are fabricated with single holographic exposure. Arrays of 21 lasers have been successfully fabricated and have around 0.8-nm wavelength spacing with a simple tuning mechanism.

Design, realization, and characterization of a ten-wavelength monolithic source for WDM applications integrating DBR lasers with a PHASAR

We present here the design, fabrication, and static as well as dynamic characteristics of a ten-wavelength, 200-GHz channel spacing emitter for wavelength-division multiplexing applications. The source is based on the monolithic integration on InP of a ten distributed Bragg reflector laser array with a square-shaped transmission response PHASAR. The specific design of the PHASAR is detailed. The continuous-wave operation-one channel at a time-demonstrates a high monomode stability with a rejection better than 32 dB for all channels and all injected currents; the 200-GHz channel spacing can be reached with an accuracy better than 25 GHz. High-speed characteristics demonstrate a 6.5-GHz direct modulation bandwidth at -3 dB for a 70-mA current in the 900-/spl mu/m-long active section. The chirp measured for a 2.5-Gb/s modulation with a 10-dB extinction ratio is less than 1.5 /spl Aring/ for every wavelength.

Sampled grating DBR laser arrays with adjustable 0.8/1.6 nm wavelength spacing

The difficulty in fabricating multiwavelength laser arrays with uniform wavelength spacing is overcome by using sampled grating distributed Bragg reflector (DBR) lasers as the constituent of a laser array. The sampling periods of the DBR mirrors are varied from laser to laser to provide reflection combs with different spacings in wavelength. Arrays of twelve lasers have been successfully fabricated with a single holographic exposure step. The wavelength spacing among the lasers can be adjusted to be around 0.8 or 1.6 nm with a simple tuning mechanism.

Design and fabrication of circular grating coupled distributed Bragg reflector lasers

The design and fabrication of circular grating surface emitting lasers are presented. The influence of device parameters on the mode selection is described. The fabrication of an InGaAs/GaAs circular grating distributed Bragg reflector (DBR) laser is presented. Significant improvement is obtained by using a quantum-well structure with a multistack and an etch-stop layer. A threshold current as low as 15 mA and an output power in excess of 170 mW without saturation are obtained. The potential of circular grating DBR laser arrays for multiwavelength operation is demonstrated.

Circular-grating surface-emitting DBR laser arrayfor free-space applications

The operation of a 2/spl times/2 circular-grating surface-emitting distributed Bragg reflector laser array is demonstrated. An InGaAs/GaAs multiquantum well structure with an etch-stop layer is used. A threshold current of /spl sim/20 mA is measured for each laser in the array. High power output with accurate wavelength control was obtained.

Four-wavelength DBR laser array with waveguide couplers fabricated using selective MOVPE growth

We developed integrated multiwavelength lasers with waveguide couplers using a novel selective metalorganic vapor-phase epitaxy (MOVPE) technique. The lasing wavelength was controlled by modulating the effective refractive index of distributed Bragg reflector (DBR) waveguides. Array lasing wavelengths were distributed from 1548.0 to 1553.5 nm with an average spacing of 1.8 nm. Output power exceeding 100 /spl mu/W was obtained for each DBR laser. The propagation loss of the waveguide coupler was about 16 dB for inner ports and 20 dB for outer ports with a 6-dB splitting loss.

Multiwavelength distributed Bragg reflector laser array fabricated using near field holographic printing with an electron-beam generated phase grating mask

We describe near optimum near field holography grating masks patterned by e-beam lithography and a distributed Bragg reflector (DBR) multiwavelength laser array fabricated using near field printing with this mask. Grating pitches in the array ranged from 242.861 to 243.750 nm in 0.127 nm steps. Data on the pitch precision and pitch adjustment is presented. Use of a conventional UV source rather than laser illumination both greatly simplified the printing process and eliminated coherent artifacts from the printed gratings. Chemically etched InP test gratings are shown to be extremely ‘‘clean’’ in appearance and low in edge roughness. DBR laser arrays designed with 100 GHz frequency separation were processed using the mask described. The measured frequency separation was 99 GHz which could be further adjusted with a tuning section of the four-section laser design. Characterization of a similar grating mask containing 16 wavelengths with similar pitch increments is also described.

8-wavelength DBR laser array fabricated with a single-step Bragg grating printing technique

An 8-wavelength distributed Bragg reflector (DBR) array for narrow channel wavelength division multiplexing (WDM) has been fabricated with a new technique for printing first-order Bragg gratings using a phase mask and a conventional incoherent source. All the distributed gratings were printed in a single photolithographic step with a slightly modified mask aligner. The DBR's excellent wavelength control for channels separated by as little as 0.8 nm is described. Many advanced photonic devices relying on gratings like quarter-wave shifted distributed feedback (DFB) lasers and wavelength division multiplexing (WDM) components can potentially be manufactured with this technique in a simple and cost-effective way. >

High efficiency surface-emitting distributed Bragg reflector laser array

A surface-emitting distributed Bragg reflector laser array with three-stripes were fabricated. The external differential quantum efficiency was 32% and the maximum output power was 500 mW.