Recently a novel photonic integration technology, based on a thin InP-based membrane, is emerging. This technology offers monolithic integration of active and passive functions in a sub-micron thick membrane. The enhanced optical confinement in the membrane results in ultracompact active and passive devices. The membrane also enables approaches to converge with electronics. It has shown high potential in breaking the speed, energy and density bottlenecks in conventional photonic integration technologies. This paper explains the concept of the InP membrane, discusses the versatility of various technology approaches and reviews the recent advancement in this field.

https://iopscience.iop.org/article/10.1088/1361-6641/abcadd/pdf

InP membrane integrated photonics research

We fabricated 1.55-µm band, broad-area, p-doped, 30-layer stacked quantum-dot (QD) laser diodes (LDs) grown on an InP(311)B substrate via a delta-doping method employing a strain compensation technique. We doped Be atoms to a depth of 5 nm from the bottom of each QD layer. The concentration of Be atoms doped in the InGaAlAs spacer layer was 1 × 1018 cm−3. We observed a strong photoluminescence emission and a relatively coherent surface of QDs using atomic force microscopy. In addition, we observed that the fabricated QD-LDs had extremely stable temperature characteristics, and a characteristic temperature T 0 of more than 2156 K was obtained.

https://iopscience.iop.org/article/10.7567/JJAP.56.04CH07/pdf

Extremely stable temperature characteristics of 1550-nm band, p-doped, highly stacked quantum-dot laser diodes

Photodetection with high responsivity at the wavelength of 1060 nm is highly desirable for light detection and ranging (LiDAR) as well as the recent emergence of swept-source optical coherent tomography (SS-OCT) applications. However, the absorption coefficient $\alpha $ of Si material at 1060 nm under the bias of 0 V is very low due to its approach to the absorption bandgap edge of Si material. In this letter, the carrier-collection-enhanced structure is proposed, which functions as multiple carrier collection paths, which enhances the external quantum efficiency of photodiodes. An efficient Si photodiode with responsivity of 0.49 A/W at 1060 nm at 0 V is demonstrated, which is 2.5 times of that of commercial products. The cost-effective fabrication of Si photodiodes greatly enhances the system performance of LiDAR and OCT.

High-Responsivity Si Photodiodes at 1060 nm in Standard CMOS Technology

Indoor optical wireless communication (OWC) using steerable infrared beams is regarded as an important component in future 5G network. Photonic integration technologies can meet the criteria of such application, and provide low-cost, high-performance and very compact chips. In this paper, we review the recent development of photonic integration technologies suitable for indoor OWC application, and discuss in detail the current status and future opportunities of several key devices, such as the chip to free space couplers, integrated receivers and transmitters.

/pdf/photonic-integration-technologies-for-indoor-optical-xnns5rvjua.pdf

Photonic integration technologies for indoor optical wireless communications

https://iopscience.iop.org/article/10.1088/1361-6463/aaf064/pdf

Low-power-consumption optical interconnect on silicon by transfer-printing for used in opto-isolators

On-chip optical interconnection is a promising technology for wiring future large-scale integrated circuits, as a means to mitigate the considerable power dissipation of traditional wiring layers. Here, we fabricate an integrated optical link using a membrane distributed-feedback (DFB) laser and a p-i-n photodiode (PD) in a butt-jointed built-in coupling geometry. The optical link is formed on a Si substrate by benzocyclobutene bonding. The integrated DFB laser shows a low-threshold current of 0.48 mA. Light transmission between the DFB laser and the p-i-n PD is confirmed with static measurements of the optical link. The optical link has a 3-dB bandwidth of 11.3 GHz at a 2.73 mA DFB laser bias current and a –3 V p-i-n PD bias voltage. A data transmission experiment of the optical link is performed, using a nonreturn to zero, pseudorandom-bit-sequence with a word length of 231-1 signals. With a DFB laser bias current of 2.5 mA, 10 Gbit/s data transmission with a bit-error-rate of 6 × 10–7 is successfully achieved.

/pdf/integrated-optical-link-on-si-substrate-using-membrane-1mlq0834cc.pdf

Integrated Optical Link on Si Substrate Using Membrane Distributed-Feedback Laser and p-i-n Photodiode

Membrane DFB lasers and photodiodes were monolithically integrated on Si substrate. A threshold current of 280 µA was obtained. A photocurrent of 3 µA was obtained for the laser output of 3 µW.

Integration of membrane-based DFB laser and PIN photodiode on Si substrate toward on-chip interconnection

We successfully demonstrated high-speed direct modulation of GaInAsP/InP membrane DFB laser on Si substrate for on-chip optical interconnection. The device showed threshold current of 0.21mA and single-mode operation with SMSR = 47dB. From small signal modulation, a record high modulation efficiency of 11GHz/mA1/2 was obtained. A 10 Gbps direct modulation with a bit-error-rate (BER) < 10−9 was demonstrated at 1mA bias current.

10 Gbps operation of membrane DFB laser on silicon with record high modulation efficiency

Impedance characteristics of a membrane DFB laser were measured to reveal an effect of parasitics on the modulation bandwidth. The cutoff frequency was obtained to be 13.7 GHz by measuring reflection S 11 . Additionally, 18 Gbit/s direct modulation was performed at a bias current of 1.5-mA.

Impedance analysis of high-speed lateral-current-injection membrane DFB laser on silicon

Recent advances of GaInAsP/InP membrane lasers will be presented. A high index-coupling grating structure enabled very-low threshold current (230 μA) as well as high-speed modulation with a record modulation current efficiency (9.9 GHz/mA1/2).

Daisuke Inoue

Papers

Integrated Optical Link on Si Substrate Using Membrane Distributed-Feedback Laser and p-i-n Photodiode

Integration of membrane-based DFB laser and PIN photodiode on Si substrate toward on-chip interconnection

10 Gbps operation of membrane DFB laser on silicon with record high modulation efficiency

Impedance analysis of high-speed lateral-current-injection membrane DFB laser on silicon

GaInAsP/InP membrane lasers