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Santa Monica, CA, United States

Agency: Department of Defense | Branch: Army | Program: STTR | Phase: Phase II | Award Amount: 503.90K | Year: 2015

Spontaneous emission is a quantum mechanical process that represents the main source of phase noise in state-of-the-art semiconductor lasers, limiting their coherence, and their suitability for high-speed communication and sensing applications. This proposal aims to develop ultra-high coherence semiconductor lasers on the Silicon/III-V platform with a quantum linewidth of

California Institute of Technology and Telaris Inc. | Date: 2014-12-30

A detection apparatus and method for FMCW LIDAR employ signals whose frequencies are modified so that low-cost and low-speed photodetector arrays, such as CCD or CMOS cameras, can be employed for range detection. The LIDAR is designed to measure the range z to a target and includes a single mode swept frequency laser (SFL), whose optical frequency is varied with time, as a result of which, a target beam which is reflected back by the target is shifted in frequency from a reference beam by an amount that is proportional to the relative range z to the target. The reflected target beam is combined with the reference beam and detected by the photodetector array. By first modulating at least one of the target and reference beams such that the difference between the frequencies of the reflected target beam and the reference beam is reduced to a level that is within the bandwidth of the photodetector array, the need for high-speed detector arrays for full-field imaging is obviated.

Vasilyev A.,California Institute of Technology | Satyan N.,California Institute of Technology | Xu S.,California Institute of Technology | Rakuljic G.,Telaris Inc. | Yariv A.,California Institute of Technology
Applied Optics | Year: 2010

We propose and demonstrate a novel approach to increase the effective bandwidth of a frequencymodulated continuous-wave (FMCW) ranging system. This is achieved by algorithmically stitching together the swept spectra of separate laser sources. The result is an improvement in the range resolution proportional to the increase in the swept-frequency range. An analysis of this system as well as the outline of the stitching algorithm are presented. Using three distinct swept-frequency optical waveforms, we experimentally demonstrate a threefold improvement in the range resolution of a three-sweep approach over the conventional FMCW method. © 2010 Optical Society of America.

Satyan N.,California Institute of Technology | Vasilyev A.,California Institute of Technology | Rakuljic G.,Telaris Inc. | White J.O.,U.S. Army | Yariv A.,California Institute of Technology
Optics Express | Year: 2012

We propose, analyze and demonstrate the optoelectronic phase-locking of optical waves whose frequencies are chirped continuously and rapidly with time. The optical waves are derived from a common optoelectronic swept-frequency laser based on a semiconductor laser in a negative feedback loop, with a precisely linear frequency chirp of 400 GHz in 2 ms. In contrast to monochromatic waves, a differential delay between two linearly chirped optical waves results in a mutual frequency difference, and an acoustooptic frequency shifter is therefore used to phase-lock the two waves. We demonstrate and characterize homodyne and heterodyne optical phase-locked loops with rapidly chirped waves, and show the ability to precisely control the phase of the chirped optical waveform using a digital electronic oscillator. A loop bandwidth of ∼ 60 kHz, and a residual phase error variance of < 0.01 rad2 between the chirped waves is obtained. Further, we demonstrate the simultaneous phase-locking of two optical paths to a common master waveform, and the ability to electronically control the resultant two-element optical phased array. The results of this work enable coherent power combining of high-power fiber amplifiers-where a rapidly chirping seed laser reduces stimulated Brillouin scattering-and electronic beam steering of chirped optical waves. © 2012 Optical Society of America.

White J.O.,U.S. Army | Vasilyev A.,California Institute of Technology | Cahill J.P.,U.S. Army | Satyan N.,California Institute of Technology | And 4 more authors.
Optics Express | Year: 2012

The output of high power fiber amplifiers is typically limited by stimulated Brillouin scattering (SBS). An analysis of SBS with a chirped pump laser indicates that a chirp of 2.5 × 1015 Hz/s could raise, by an order of magnitude, the SBS threshold of a 20-m fiber. A diode laser with a constant output power and a linear chirp of 5 × 1015 Hz/s has been previously demonstrated. In a low-power proof-of-concept experiment, the threshold for SBS in a 6-km fiber is increased by a factor of 100 with a chirp of 5 × 1014 Hz/s. A linear chirp will enable straightforward coherent combination of multiple fiber amplifiers, with electronic compensation of path length differences on the order of 0.2 m. ©2012 Optical Society of America.

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