CW single-wavelength emission by using novel asymmetric configuration for active multi-mode interferometer laser diodes

Abstract

Abstract:We report CW single-wavelength emission at RT from non-grating active multi-mode interferometer laser diodes (MMI LDs) by using an asymmetric configuration. Fabricated devices showed sidemode suppression ratio (SMSR) of 31 dB (λ = 1.56 μm). We also present the modulation characteristics of this novel device at 1.25 Gbps for a 2 7 − 1 pseudorandom binary sequence.

A space mode selective light source with over 40 GHz direct modulation bandwidth

“…Such multiple sub-peaks result from the multiple inner oscillating F-P cavities which is formed because of the high-mesa waveguide structure. 26,31) Table I shows the evaluated wavelength differences and resonance peaks of a small signal. Besides the resonance peak at 37 GHz, the other resonance peaks are attributed to wavelength differences from the Fabry-Pérot cavity overlapping.…”

“…In order to form the inner reflection mirror at the MMI edge, high mesa waveguide structure is introduced. 31) The cross-section scheme of the waveguide is shown in Fig. 4(b).…”

High intrinsic modulation bandwidth InGaAsP/InGaAsP 1.55 µm asymmetric active multimode interferometer laser diode by using split pump configuration

“…The fabricated device does not include any grating structure to achieve single wavelength output. 26) The designed MMI consists of asymmetric 1 © 1 MMI coupler with both port connected to single mode high mesa wave guide. Utilization of high mesa wave guide provides the benefit of high contrast in the refractive index of the high-mesa realizing "sharp focus" in the self-imaging of active MMI.…”

“…31) The high-mesa asymmetric configuration also ensures single wavelength characteristics namely "interference in longitudinal mode". 26) For the actual implemented devices, the total length of the cavity was 315 µm. The MMI section width was set to 8 µm.…”

“…A semiconductor laser with an active multimode interference (MMI) cavity is one of the most promising broad area structures in this regard. Active MMI-laser diode (LD) offers regular single mode output, 26) which can be coupled into a standard single mode fiber without using an additional output mode trimming device. Potential advantages over conventional semiconductor laser also includes the smaller size, simplicity of fabrication, high fabrication tolerance, low series resistance and compact split modulation section, makes it a promising candidate for short distance applications.…”