High-frequency small-signal modulation characteristics of short-cavity InGaAsP lasers

Tucker, R.S.; Lin, Chinlon; Burrus, C.A.; Besomi, P.; Nelson, R. J.

doi:10.1049/el:19840272

Cited by 22 publications

(5 citation statements)

References 3 publications

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“…Finally, the photon lifetime, τ ph , can be reduced by decreasing the laser cavity length. Short-cavity lasers have been shown to have enhanced bandwidths [2,20], though this may be at the expense of output power. Experimental values of K can be as low as 0.2-0.4 ns in short-cavity, edge-emitting lasers, implying a maximum modulation bandwidth in excess of 20-40 GHz [21].…”

Section: Modulation Responsementioning

confidence: 99%

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Fast phenomena in semiconductor lasers

2000

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Although diode lasers are almost ideal sources for ultrahigh-speed data communication systems, system performance remains critically dependent on the quality of the optical pulses that they generate. Uniquely among lasers, the output power can be modulated directly by modulating the diode current. However, this leads to relaxation oscillations and a roll-off at high frequencies that is superimposed on the frequency response of the drive circuit. This is limited by parasitics and maximum modulation frequencies range from 1 to 70 GHz, depending on the type of laser and its packaging. The higher values are obtained with short cavity lengths and tight optical confinement, the highest frequencies being achieved in vertical-cavity devices. Modulation bandwidth is usually limited by circuit parasitics, device heating and the maximum power-handling capability of the laser facets.The generation of picosecond and femtosecond pulses demands special techniques and three-gain switching, Q-switching and mode locking-are discussed in detail, with their relative advantages and disadvantages compared. Very short pulses inherently contain a significant spread of wavelengths and their generation requires the optical gain in the laser medium to extend across that wavelength range. While diode lasers satisfy this criterion better than many other types, the effect of gain non-linearities and carrier-transport effects prevent the Fourier-transform limit from being achieved in practice. As a result, external pulse-compression techniques, which exploit the detailed temporal and spectral properties of the laser pulses, such as frequency chirping, self-phase modulation and group velocity dispersion, are becoming more important, and diode lasers are increasingly challenged as primary sources by compact, efficient, diode-pumped solid-state lasers.The paper summarizes the levels of maximum pulse power and minimum duration that have been achieved using the various techniques.

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Section: Modulation Responsementioning

confidence: 99%

“…Figure20. Evolution of the spectra of 2 ps pulses (left-hand traces) and 500 fs pulses (right-hand traces) in a 300 µm GaAs SLA with G 1 = 27 dB and 0.4 pJ, Gaussian-shaped, unchirped input pulses.…”

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confidence: 99%

Fast phenomena in semiconductor lasers

2000

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“…4) [17]. Equation (5) points out three obvious ways to increase the modulation bandwidth: (1) by increasing the differential gain g ' (lowering the operating temperature [ 181, using quantum well structure, especially multiquantum well structure [ 191, heavily doping the active region [20], using detuning techniques in the case of DFB lasers [2 11 are effective ways to do so); (2) by decreasing the photon lifetime rP (the use of a short laser cavity [22] is the most popular way); (3) by increasing the photon density inside the active region (increasing the bias optical power will serve this purpose). In view of this point, a design that can increase the maximum optical power while maintaining g' and rP unchanged, will also benefit the high-speed operation.…”

Section: High-frequency Operation Of Semiconductor Lasersmentioning

confidence: 99%

“…The lasers used for high-power operation are usually long (e.g., 700 pm) [5] and a junction down mounting configuration is commonly adopted. On the other hand, short cavity lasers [22] are frequently used to demonstrate high-resonance frequency. Heavily doping the active layer seems to increase the differential gain, thus making laser faster [20], but it may reduce the maximum power [ 171.…”

Section: Some Consideration On the Combined High-power And High-speedmentioning

confidence: 99%