Polarization instability and relative intensity noise in vertical-cavity surface-emitting lasers

Abstract

We observe a polarization instability in circularly symmetric vertical-cavity surface-emitting lasers. A relatively long time, 3–5 ns, is required to establish a dominant polarization state. Under high-speed digital modulation this leads to strong enhancement, 20–30 dB, in polarization resolved low-frequency relative intensity noise. This polarization instability is accurately described by a simple rate-equation model. A similar increase in relative intensity noise, under dc bias, is caused by energy partition between orthogonally polarized modes.

Transient response of vertical-cavity surface-emitting lasers of different active-region diameters

“…In addition, we studied the polarization properties of the transient response. It had been shown that these devices usually present a dominant polarization state during dc operation [14], [15] and that the characteristic time for achieving this state is of the order of a few nanoseconds [16], [17]. Our measurements complement this knowledge, showing that the two polarization states of all the transverse modes are present during subnanosecond excitation and that they evolve with the same dynamics.…”

“…In spite of the lack of polarization selection, one of these two states is usually dominant during dc operation. It has been shown that the characteristic time for establishing a dominant polarization state is of the order of 2-5 ns for a gain-guided VCSEL [16]. Polarization switching between these polarized states has also been reported during slow [15], [23] and fast [24] current ramp excitations.…”

“…In cylindrical symmetric VCSEL's, the laser emission has been found to be linearly polarized and aligned with the and crystal axes [14]- [16]. In spite of the lack of polarization selection, one of these two states is usually dominant during dc operation.…”

Data Pattern Dependence of VCSEL Far-Field Distributions

“…With the assumption that the fundamental mode contributes more on-axis power and higher order modes contribute more power in the wings of the beam distribution, it appears that the oxideconfined devices in this study behave opposite to those in [7]. Here, the fundamental mode appears to overshoot and highorder mode undershoots.…”

“…Prior investigations of polarization resolved waveforms led the authors of [7] to conclude that a low-to-high drive transition on an implant-confined VCSEL caused the high-order mode to overshoot and the low-order mode to undershoot. With the assumption that the fundamental mode contributes more on-axis power and higher order modes contribute more power in the wings of the beam distribution, it appears that the oxideconfined devices in this study behave opposite to those in [7].…”