Polarization-insensitive electroabsorptive modulation using interdiffused InGaAs(P)-InP quantum wells

IEEE J. Select. Topics Quantum Electron.

Chan

2003

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Abstract-Diffused quantum-well (QW) distributed feedback (DFB) lasers and optical amplifiers will be theoretically analyzed in this paper. For DFB lasers, a design rule will be proposed and the validity of the design rule will be discussed with respect to changes in the injected carrier density. The range of grating period, which can be used in the design, is discussed. As a consequence, the maximum tuning range of the emission wavelength can be estimated without involving the time-consuming self-consistent simulation. The features of polarization independence of optical amplifiers achieved by using diffused QWs are also discussed. Our theoretical results successfully explain why polarization independence can achieve in the long-wavelength tail of the modal gain and absorption coefficient but not at photon energies above the transition edge. This explanation applies to other tensile-strained QWs for polarization-independent applications. The understanding is crucial for optimizing polarization-independent devices. To conclude, our analysis of the diffused QW optical devices demonstrates that QW intermixing technology is a practical candidate for not only realizing monolithic photonic integrated circuit, but also enhancing optical device performance.Index Terms-Diffused quantum well (DFQW), distributed feedback (DFB) lasers, optical amplifiers, polarization independence, quantum-well interdiffusion, quantum-well intermixing, wavelength tuning.

Section: Polarization-independent Optical Amplifiersmentioning

confidence: 99%

Theoretical analysis of diffused quantum-well lasers and optical amplifiers

IEEE J. Select. Topics Quantum Electron.

Chan

2003

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“…The contrast ratio for a modulator is defined as the relative optical intensity modulation and is given as [15] CR (dB)…”

Section: Computational Considerationsmentioning

confidence: 99%

Interdiffused AlGaAs-GaAs quantum well for improved electroabsorptive modulation

IEEE J. Quantum Electron.

1998

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Abstract-This is a theoretical study of the effects of two asgrown structural parameters on the modulation properties of Al x Ga 10x As-GaAs quantum wells (QW's), which are the Al concentration in barrier and the thickness of the well layer serving as initial conditions before interdiffusion. The results show that, with a larger Al concentration and a wider well width, the range of interdiffusion for an enhanced electroabsorption (EA) change increases with both of these parameters, while insertion loss increases with the former and decreases with the latter. However, the increase in loss is lower than that of the rectangular QW for the same magnitude of absorption change. The range of a tunable absorption-peak wavelength produced by interdiffussion increases with increasing Al concentration and decreases with increasing well width. Moreover, in a moderately interdiffused QW, the required bias reduces for the same level of EA modulation. For the best device operation, interdiffused QW's with the Al concentration between 0.3 and 0.4 and well width between 10 and 12 nm are most suitable for developing a general-purpose electroabsorptive modulator. When applied in high-speed modulators, the EA of a wide and shallow QW active-region structure can be further enhanced by the use of corresponding interdiffusion.Index Terms-Diffusion process, electroabsorption, intermixing quantum well, modeling, optical materials/devices, quantumconfined Stark effect, quantum-well devices, tunable devices.

“…The relationship between and is given by (1) where is the angular frequency and is the speed of light. This model of has been described previously [13], [14] and is not the subject of the work reported here. The model for is described in [15] and [16].…”

Section: A Optical Properties Of Qwmentioning

confidence: 99%

“…Since the dielectric constants are different in each layer of the heterojunction structure, the derivation of the relevant quantities is rather complex. The potential difference across the depletion width is given by and, by using (13), and can be expressed in terms of the depletion layer thickness and the carrier density of the p-i-n structure. The integrated form of (13) is expressed as a quadratic equation for the depletion layer width and, thus, the solution for can be written as (14) where where is the dielectric constant, is the dopant concentration, and the subscripts , , and refer to the relevant layers of the p-i-n structure, respectively, is the thickness of the active region, and is an electronic charge.…”

Section: E the P-i-n Junction Depletion Regionmentioning

confidence: 99%

“…The expressions of and are taken from [13] together with (1), while is taken from [17]. In the calculation of the as-grown square QW, the is calculated by weighting the barrier and well together in a ratio of well width ( ) to barrier width ( ) (6) For the case of a diffused QW, we divide each well and barrier layer into 20 subintervals and at each subinterval is calculated using the diffused Al concentration profile.…”

Section: A Optical Properties Of Qwmentioning

confidence: 99%

See 1 more Smart Citation

AlGaAs-GaAs quantum-well electrooptic phase modulator with disorder delineated optical confinement

IEEE J. Quantum Electron.

Weiss

1998

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Abstract-Waveguide phase modulators, with 0.5-and 1-m quantum-well (QW) active regions which are defined by impurityinduced disordering are investigated theoretically. By controlling the extent of the interdiffusion in the lateral claddings, the refractive index difference between the core and claddings is used to provide single-mode operation. Strong optical confinement, which is required to produce single-mode high-efficiency modulation, requires the peak impurity concentration to be at the center of the QW active region. Moreover, the annealing time needs to be optimized so that single mode can be maintained at the desired bias field. A low dopant concentration is also expected to minimize the destruction of the modulator structure. The results show that since the core/cladding interface is graded, the width of the metal contact is important. A comparison of modulation efficiency for active layer thicknesses of 0.5 and 1.0 m shows that the 0.5-m one is a more efficient structure and its absorption loss can be reduced by increasing the applied field from 50 to 100 kV/cm.