Emission regimes in a distributed feedback tapered master-oscillator power-amplifier at 1.5 μm

Abstract

Integrated master-oscillator power amplifiers driven under steady-state injection conditions are known to show a complex dynamics resulting in a variety of emission regimes. We present experimental results on the emission characteristics of a 1.5 urn distributed feedback tapered master-oscillator power-amplifier in a wide range of steady-state injection conditions, showing different dynamic behaviors. The study combines the optical and radio-frequency spectra recorded under different levels of injected current into the master oscillator and the power amplifier sections. Under low injection current of the master oscillator the correlation between the optical and radio-frequency spectral maps allows to identify operation regimes in which the device emission arises from either the master oscillator mode or from the compound cavity modes allowed by the residual reflectance of the amplifier front facet. The quasi-periodic occurrence of these emission regimes as a function of the amplifier current is interpreted in terms of a thermally tuned competition between the modes of the master oscillator and the compound cavity modes. Under high injection current of the masteroscillator, two different regimes alternate quasi-periodically as a function of the injected current in the power amplifier: a stable regime with a single mode emission at the master oscillator frequency, and an unstable and complex self-pulsating regime showing strong peaks in the radio-frequency spectra as well as multiple frequencies in the optical spectra.

Emission Characteristics of a 1.5- <inline-formula> <tex-math notation="TeX">$\mu$</tex-math></inline-formula>m All-Semiconductor Tapered Master Oscillator Power Amplifier

“…At low I MO , they are clearly visible, whereas at higher values of I MO they are only apparent in the derivatives of the P-I curves (not shown). These ripples are related to transitions between different emission regimes [9], which will be later described in detail.…”

“…In previous works [2], [9], we have also reported a very rich spectral dynamics with different emission regimes and a quasi-periodic alternation between them as a function of the CW currents in both sections. All these CW effects are expected to have a substantial impact on the operation of MOPAs in direct modulation and therefore it is of primary interest the detailed characterization and understanding of the performance of these devices under CW injection conditions.…”

A Review of High-Power Semiconductor Optical Amplifiers in the 1550 nm Band

“…To further improve the output power, the MOPA often uses a tapered SOA. As shown in Figure 7, the MOPA is a two-segment structure including a DFB laser and a high-power amplifier, or a three-segment structure including a DFB laser, a modulation part, and a high-power amplifier [90][91][92][93][94]. Faugeron M's research group showed that the instability of the MOPA device comes primarily from two factors-that is, DFB laser interference by the light reflected onto the DFB laser from the device coupling and the mode competition between the entire cavity defined by the two end facets and the DFB laser.…”