Silicon photonics (SiPh) enables compact photonic integrated circuits (PICs), showing superior performance for a wide variety of applications. Various optical functions have been demonstrated on this platform that allows for complex and powerful PICs. Nevertheless, laser source integration technologies are not yet as mature, hampering the further cost reduction of the eventual Si photonic systems-on-chip and impeding the expansion of this platform to a broader range of applications. Here, we discuss a promising technology, micro-transfer-printing (μTP), for the realization of III-V-on-Si PICs. By employing a polydimethylsiloxane elastomeric stamp, the integration of III-V devices can be realized in a massively parallel manner on a wafer without substantial modifications to the SiPh process flow, leading to a significant cost reduction of the resulting III-V-on-Si PICs. This paper summarizes some of the recent developments in the use of μTP technology for realizing the integration of III-V photodiodes and lasers on Si PICs.

An electrically pumped DFB laser integrated on and coupled to a silicon waveguide circuit is demonstrated by transfer printing a 40 × 970 μm III-V coupon, defined on a III-V epitaxial wafer. A second-order grating defined in the silicon device layer with a period of 477 nm and a duty cycle of 75% was used for realizing single mode emission, while an adiabatic taper structure is used for coupling to the silicon waveguide layer. 18 mA threshold current and a maximum single-sided waveguide-coupled output power above 2 mW is obtained at 20°C. Single mode operation around 1550 nm with > 40 dB side mode suppression ratio (SMSR) is realized. This new integration approach allows for the very efficient use of the III-V material and the massively parallel integration of these coupons on a silicon photonic integrated circuit wafer. It also allows for the intimate integration of III-V opto-electronic components based on different epitaxial layer structures.

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A 4-channel silicon photonics transceiver array for Point-to-Point (P2P) fiber-tothe-home (FTTH) optical networks at the central office (CO) side is demonstrated. A III-V O band photodetector array was integrated onto the silicon photonic transmitter through transfer printing technology, showing a polarization-independent responsivity of 0.39 -0.49 A/W in the O band. The integrated PDs (30×40 μm 2 mesa) have a 3 dB bandwidth of 11.5 GHz at -3 V bias. Together with high-speed C band silicon ring modulators whose bandwidth is up to 15 GHz, operation of the transceiver array at 10 Gbit/s is demonstrated. The use of transfer printing for the integration of the III-V photodetectors allows for an efficient use of III-V material and enables the scalable integration of III-V devices on silicon photonics wafers, thereby reducing their cost.

Abstract-A sequence of partially reflective slots etched into an active ridge waveguide of a 1.5 µm laser structure is found to provide sufficient reflection for lasing. Mirrors based on these reflectors have strong spectral dependence. Two such active mirrors together with an active central section are combined in a Vernier configuration to demonstrate a tunable laser exhibiting 11 discrete modes over a 30 nm tuning range with mode spacing around 400 GHz and side-mode suppression ratio larger than 30 dB. The individual modes can be continuously tuned by up to 1.1 nm by carrier injection and by over 2 nm using thermal effects. These mirrors are suitable as a platform for integration of other optical functions with the laser. This is demonstrated by monolithically integrating a semiconductor optical amplifier with the laser resulting in a maximum channel power of 14.2 dBm from the discrete modes.