Compact electro-absorption modulator integrated with vertical-cavity surface-emitting laser for highly efficient millimeter-wave modulation

Abstract

We demonstrate a compact electro-absorption slow-light modulator laterally-integrated with an 850 nm vertical-cavity surface-emitting laser (VCSEL), which enables highly efficient millimeter-wave modulation. We found a strong leaky travelling wave in the lateral direction between the two cavities via widening the waveguide width with a taper shape. The small signal response of the fabricated device shows a large enhancement of over 55 dB in the modulation amplitude at frequencies beyond 35 GHz; thanks to the photon-photon resonance. A large group index of over 150 in a Bragg reflector waveguide enables the resonance at millimeter wave frequencies for 25 μm long compact modulator. Based on the modeling, we expect a resonant modulation at a higher frequency of 70 GHz. The resonant modulation in a compact slow-light modulator plays a significant key role for high efficient narrow-band modulation in the millimeter wave range far beyond the intrinsic modulation bandwidth of VCSELs.

Enhanced high-frequency modulation of single-mode 850nm VCSELs via dual transverse-cavity integration

“…This VCSEL amalgamates laterally with a compact transverse cavity, targeting an augmented modulation efficiency within the millimeter-wave spectrum for high-speed modulations in datacenter networks. The empirical findings on this coupled cavity VCSEL are congruent with the theoretical modeling result, indicating a 60% increase in the small-signal modulation bandwidth [25]. To increase the transmission distance in fiber, the modal dispersion in multi-mode fiber (MMF) could be reduced using single mode VCSELs.…”

Modeling of Millimeter-Wave Modulation Characteristics of Semiconductor Lasers under Strong Optical Feedback

“…Therefore, this resonance is referred to as “photon-photon resonance” [13]. Similar effect is observed in vertical-cavity surface-emitting lasers (VCSELs) coupled to a transverse cavity [22], in which the photon-photon resonance is induced by transverse oscillating modes. Because the shown IM responses have an unused frequency between the frequency f 3 dB and the enhanced mm-narrow bands, this modulation enhancement is not favored for applications in telecommunications.…”

“…Most recently the author's group [20] has newly reported using strong OFB to boost the modulation frequencies over an ultrahigh frequency passband over 55 GHz and has shown improvement of the gain of a corresponding RoF link by about 20 dB. Such enhancement in the IM response over an ultrahigh frequency passband was attributed as a type of photon-photon resonance due to coupling of oscillating modes in the coupled cavity [13, 21, 22]. It is obtained when the nonmodulated laser keeps operation in CW under strong OFB.…”

Modeling of noise and distortion associated with ultra‐high‐speed modulation of VCSEL with slow‐light feedback

“…Also, the authors demonstrated resonance modulation centered on a frequency of 40 GHz with large enhancement of over 30 dB in the modulation amplitude . This resonance modulation was proved to be due to photon–photon resonance (PPR) between two transverse oscillating modes under strong slow‐light feedback . This PPR results in an additional resonance peak to the modulation response at frequencies that potentially exceed the conventional carrier‐photon resonance (CPR) frequency a few times .…”