公开(公告)号：US20210208470A1

公开(公告)日：2021-07-08

申请号：US17091905

申请日：2020-11-06

Applicant: Rajeev J. RAM ,  Dodd Joseph GRAY ,  Amir H. Atabaki ,  Marc De Cea Falco

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.

公开(公告)号：US07429735B2

公开(公告)日：2008-09-30

申请号：US11376722

申请日：2006-03-15

Applicant: Dietrich Lueerssen ,  Rajeev J. Ram ,  Janice A. Hudgings ,  Peter M. Mayer

Inventor： Dietrich Lueerssen ,  Rajeev J. Ram ,  Janice A. Hudgings ,  Peter M. Mayer

IPC: G01N21/17

CPC classification number: G01J5/0003 ,  G01K11/125 ,  G01N21/1717 ,  G01N21/55 ,  G01N25/18 ,  G01N2021/1731

Abstract: The invention is directed to systems and methods of digital signal processing and in particular to systems and methods for measurements of thermoreflectance signals, even when they are smaller than the code width of a digital detector used for detection. For example, in some embodiments, the number of measurements done is selected to be sufficiently large so as to obtain an uncertainty less than the code width of the detector. This allows for obtaining images having an enhanced temperature resolution. The invention is also directed to methods for predicting the uncertainty in measurement of the signal based on one or more noise variables associated with the detection process and the number of measurement iterations.

Abstract translation: 本发明涉及数字信号处理的系统和方法，特别涉及用于测量热反射信号的系统和方法，即使它们小于用于检测的数字检测器的代码宽度。 例如，在一些实施例中，完成的测量数量被选择为足够大，以便获得小于检测器的代码宽度的不确定性。 这允许获得具有增强的温度分辨率的图像。 本发明还涉及用于基于与检测过程相关联的一个或多个噪声变量和测量迭代次数来预测信号测量的不确定性的方法。

公开(公告)号：US10656012B2

公开(公告)日：2020-05-19

申请号：US16229355

申请日：2018-12-21

Applicant: Amir H. Atabaki ,  Rajeev J. Ram ,  William F. Herrington

Inventor： Amir H. Atabaki ,  Rajeev J. Ram ,  William F. Herrington

IPC: G01J3/44 ,  G01J3/02 ,  G01J3/10 ,  G01J3/28 ,  G01J3/18 ,  G01N21/65 ,  G01J1/42 ,  G01J3/433 ,  G02B6/293

Abstract: In swept source Raman (SSR) spectroscopy, a swept laser beam illuminates a sample, which inelastically scatters some of the incident light. This inelastically scattered light is shifted in wavelength by an amount called the Raman shift. The Raman-shifted light can be measured with a fixed spectrally selective filter and a detector. The Raman spectrum can be obtained by sweeping the wavelength of the excitation source and, therefore, the Raman shift. The resolution of the Raman spectrum is determined by the filter bandwidth and the frequency resolution of the swept source. An SSR spectrometer can be smaller, more sensitive, and less expensive than a conventional Raman spectrometer because it uses a tunable laser and a fixed filter instead of free-space propagation for spectral separation. Its sensitivity depends on the size of the collection optics. And it can use a nonlinearly swept laser beam thanks to a wavemeter that measures the beam's absolute wavelength during Raman spectrum acquisition.

公开(公告)号：US06587492B2

公开(公告)日：2003-07-01

申请号：US09797188

申请日：2001-03-01

Applicant: Steven G. Patterson ,  Rajeev J. Ram

Inventor： Steven G. Patterson ,  Rajeev J. Ram

IPC: H01S500

CPC classification number: B82Y20/00 ,  H01S5/2004 ,  H01S5/3095 ,  H01S5/34 ,  H01S5/4043 ,  H01S5/423

Abstract: A bipolar cascade-ARROW laser includes a plurality of core regions, at least one spacer disposed between each the plurality of core regions with each of the at least one spacers provided from a material having an index of refraction which is higher than an index of refraction of a material from which the core regions are provided. The bipolar cascade-ARROW laser further includes an anti-reflector disposed against each of the outermost ones of the core regions and at least one quantum well disposed in each of the plurality of core regions.

Abstract translation: 双极性级联-ARROW激光器包括多个芯区域，至少一个间隔物设置在每个多个芯区域之间，其中至少一个间隔物中的每一个由具有高于折射率的折射率的材料提供 提供芯区域的材料。 双极级联-ARROW激光器还包括针对核心区域中的最外侧核心区域中的每一个设置的反射器和设置在多个核心区域中的每一个中的至少一个量子阱。

公开(公告)号：US06921195B2

公开(公告)日：2005-07-26

申请号：US10365101

申请日：2003-02-12

Applicant: Kevin P. Pipe ,  Rajeev J. Ram

Inventor： Kevin P. Pipe ,  Rajeev J. Ram

IPC: G01K3/00 ,  G01N25/18 ,  G01N25/00 ,  G01K17/20

CPC classification number: G01K3/00 ,  G01N25/18

Abstract: A method and apparatus for performing characterization of devices is presented. The characteristic of the device are determined by obtaining a first temperature measurement in a first location of a device, obtaining a second temperature measurement, computing the difference between the temperature measurements and, using the temperatures and/or the temperature difference, a characteristic of the device is determined.

Abstract translation: 提出了一种用于执行设备表征的方法和装置。 通过在器件的第一位置获得第一温度测量值，获得第二温度测量值，计算温度测量值之间的差值，并使用温度和/或温度差异来确定器件的特性来确定器件的特性 设备确定。

公开(公告)号：US06834134B2

公开(公告)日：2004-12-21

申请号：US09816937

申请日：2001-03-23

Applicant: James F. Brennan, III ,  Patrick C. Chou ,  Harry L. T. Lee ,  Rajeev J. Ram ,  Hermann A. Haus ,  Erich P. Ippen

Inventor： James F. Brennan, III ,  Patrick C. Chou ,  Harry L. T. Lee ,  Rajeev J. Ram ,  Hermann A. Haus ,  Erich P. Ippen

IPC: G02B634

CPC classification number: H01S5/0622 ,  G02B6/2932 ,  H01S5/1212 ,  H01S5/146

Abstract: A method and apparatus are provided for generating short (e.g., picosecond) pulses using a 2 section 1553 nm DBR laser without gain switching nor external modulation. The center wavelength of the DBR section is modulated at 0.5 GHz to generate a constant amplitude frequency modulated optical wave Large group velocity dispersion is then applied with a chirped fiber Bragg grating to convert the FM signal to a pulse stream.

Abstract translation: 提供了一种使用2部分1553nm DBR激光器在没有增益切换或外部调制的情况下产生短（例如，皮秒）脉冲的方法和装置。 DBR部分的中心波长被调制在0.5GHz，以产生恒定幅度的调频光波，然后用啁啾光纤布拉格光栅施加大群速度色散，以将FM信号转换成脉冲流。

公开(公告)号：US20220034715A1

公开(公告)日：2022-02-03

申请号：US17335299

申请日：2021-06-01

Applicant: Rajeev J. RAM ,  Amir H. Atabaki ,  Nili Persits ,  Jaehwan Kim

Inventor： Rajeev J. RAM ,  Amir H. Atabaki ,  Nili Persits ,  Jaehwan Kim

IPC: G01J3/02 ,  G01N21/65 ,  G01J3/44

Abstract: Swept-source Raman spectroscopy uses a tunable laser and a fixed-wavelength detector instead of a spectrometer or interferometer to perform Raman spectroscopy with the throughput advantage of Fourier transform Raman spectroscopy without bulky optics or moving mirrors. Although the tunable laser can be larger and more costly than a fixed wavelength diode laser used in other Raman systems, it is possible to split and switch the laser light to multiple ports simultaneously and/or sequentially. Each site can be monitored by its own fixed-wavelength detector. This architecture can be scaled by cascading fiber switches and/or couplers between the tunable laser and measurement sites. By multiplexing measurements at different sites, it is possible to monitor many sites at once. Moreover, each site can be meters to kilometers from the tunable laser. This makes it possible to perform swept-source Raman spectroscopy at many points across a continuous flow manufacturing environment with a single laser.

公开(公告)号：US20210389612A1

公开(公告)日：2021-12-16

申请号：US17227457

申请日：2021-04-12

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

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

IPC: G02F1/025 ,  G02F1/015

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：US20210091252A1

公开(公告)日：2021-03-25

申请号：US17032223

申请日：2020-09-25

Applicant: Amir H. Atabaki ,  Rajeev J. RAM ,  Ebrahim Dakhil Al Johani

Inventor： Amir H. Atabaki ,  Rajeev J. RAM ,  Ebrahim Dakhil Al Johani

IPC: H01L31/105 ,  H01L31/0368

Abstract: Photodetectors using photonic crystals (PhCs) in polysilicon film that include an in-plane resonant defect. A biatomic photodetector includes an optical defect mode that is confined from all directions in the plane of the PhC by the photonic bandgap structure. The coupling of the resonance (or defect) mode to out-of-plane radiation can be adjusted by the design of the defect. Further, a “guided-mode resonance” (GMR) photodetector provides in-plane resonance through a second-order grating effect in the PhC. Absorption of an illumination field can be enhanced through this resonance.

公开(公告)号：US08408786B2

公开(公告)日：2013-04-02

申请号：US12115201

申请日：2008-05-05

Applicant: Janice A. Hudgings ,  Rajeev J. Ram ,  Maryam Farzaneh

Inventor： Janice A. Hudgings ,  Rajeev J. Ram ,  Maryam Farzaneh

IPC: G01K3/00 ,  G01K1/00 ,  G01K11/00

CPC classification number: G01K11/125

Abstract: In one aspect, the present invention provides techniques and apparatus for optical characterization of photonic devices and/or circuits. By way of example, the techniques can be used to identify damaged devices in photonic integrated circuits. In some embodiments, thermal imaging is employed as a diagnostic tool for characterizing the devices/circuits under investigation. For example, in one embodiment, integrated cascaded semiconductor amplifiers can be characterized using amplified spontaneous emission from one amplifier as a thermal modulation input to another amplifier. A thermoreflectance image of the second amplifier can reveal flaws, if present. Further, in some embodiments, thermal imaging in conjunction with a total energy model can be employed to characterize the elements of photonic circuits optically and/or to map the optical power distribution throughout the circuits.

Abstract translation: 一方面，本发明提供了用于光子器件和/或电路的光学表征的技术和装置。 作为示例，这些技术可用于识别光子集成电路中的损坏设备。 在一些实施例中，热成像被用作诊断工具，用于表征所研究的装置/电路。 例如，在一个实施例中，可以使用来自一个放大器的放大的自发发射作为热调制输入到另一个放大器来表征集成级联半导体放大器。 第二放大器的反射反射图像可以显示缺陷（如果存在）。 此外，在一些实施例中，可以采用结合总能量模型的热成像来光学地表征光子电路的元件和/或映射整个电路中的光功率分布。