公开(公告)号：US11650440B1

公开(公告)日：2023-05-16

申请号：US17353081

申请日：2021-06-21

Applicant: Massachusetts Institute of Technology

Inventor： Marc De Cea Falco ,  Amir H. Atabaki ,  Rajeev J. Ram

IPC: G02F1/025 ,  G02F1/225 ,  H01L31/0745

CPC classification number: G02F1/025 ,  G02F1/2257 ,  H01L31/0745

Abstract: A photovoltaic modulator utilizes free carriers generated by absorption of optical radiation passing through the modulator to achieve ultra-low energy modulation of the radiation. The photovoltaic modulator can also function as an electro-optic transducer for low-power, low-EMI, high-density sensing applications.

公开(公告)号：US11624941B2

公开(公告)日：2023-04-11

申请号：US17227457

申请日：2021-04-12

Applicant: Massachusetts Institute of Technology

Inventor： Rajeev J. Ram ,  Marc De Cea Falco ,  Jin Xue

IPC: G02F1/025

Abstract: Semiconductor optical modulators are described that utilize bipolar junction transistor (BJT) structure within the optical modulator. The junctions within the BJT can be designed and biased to increase modulator efficiency and speed. An optical mode may be located in a selected region of the BJT structure to improve modulation efficiency. The BJT structure can be included in optical waveguides of interferometers and resonators to form optical modulators.

公开(公告)号：US11506951B2

公开(公告)日：2022-11-22

申请号：US17091905

申请日：2020-11-06

Applicant: Massachusetts Institute of Technology

Inventor： Rajeev J. Ram ,  Dodd Joseph Gray ,  Amir H. Atabaki ,  Marc De Cea Falco

IPC: G02F1/225 ,  G02F1/21 ,  G02F1/01

Abstract: Optical read-out of a cryogenic device (such as a superconducting logic or detector element) can be performed with a forward-biased optical modulator that is directly coupled to the cryogenic device without any intervening electrical amplifier. Forward-biasing at cryogenic temperatures enables very high modulation efficiency (1,000-10,000 pm/V) of the optical modulator, and allows for optical modulation with millivolt driving signals and microwatt power dissipation in the cryogenic environment. Modulated optical signals can be coupled out of the cryostat via an optical fiber, reducing the thermal load on the cryostat. Using optical fiber instead of electrical wires can increase the communication bandwidth between the cryogenic environment and room-temperature environment to bandwidth densities as high as Tbps/mm2 using wavelength division multiplexing. Sensitive optical signals having higher robustness to noise and crosstalk, because of their immunity to electromagnetic interference, can be carried by the optical fiber.