Selective Lasing of Guided Modes from Hollow Square Semiconductor Microcavities

Abstract

We demonstrated the selective lasing of guided modes from hollow square microcavities having an InGaAsP/InGaAs quantum well gain layer. For hollow square cavities with symmetric convex corners, ring-type whispering gallery modes (WGMs) originating from total reflections of light at the four corners were lased. By modifying the corner shape to be asymmetric and concave, guided modes originating from total reflections at the inner and outer flat boundaries were selectively lased. We determined that the lasing modes were guided modes by analyzing measured spectra. The observed quality factor Q was smaller than that of ring-type WGMs owing to enhanced total reflection loss.

Lasing of Coupled Guided Modes in Modified Hollow Hexagonal Semiconductor Cavities

“…The mode spacing ∆λ of the resonance modes in a semiconductor laser can be expressed as [16,17] (4) where the group index M (λ ) accounts for the dispersion in the semiconductor material and is weakly dependent on λ .…”

“…The experimental setup and epistructure used for the semiconductor cavities were similar to those in our previous studies [16,17]. InGaAsP/InGaAs multiple quantum wells (MQWs, λ g ≅1.55 µm) surrounded by two confinement layers were used for the laser gain medium.…”

“…Recently, a different type of WG-like modes called "guided modes" have been reported in hollow polygonal (square or hexagonal) geometries, wherein TIR occurs not only at the outer boundaries but also at the inner boundaries [15][16][17]. Figure 1 shows the previous hollow hexagonal cavity (outer size   , inner size   , and refractive index m) and the ray trajectory corresponding to the guided modes [17].…”

Bow-tie Mode Lasing in a Grooved Rectangular Semiconductor Microcavity

“…3(a), which could be attributed to the simultaneous lasing of open orbit modes. The free spectral range Δλ FSR or mode spacing in the semiconductor laser can be approximately expressed as [15] where M(λ) accounts for the dispersion in m of the semiconductor epiwafer and is a function of λ. From Eq.…”

“…The experimental setup for bow-tie mode lasing was similar to that used previously [15,16]. InGaAsP/InGaAs multiple quantum wells (8 MQWs, λ g~1 .3 μm) were surrounded by two confinement layers in the epistructure.…”