Precision Electro-Optic, Waveguide,

World record for optical time delay device realized by Vescent scientists

vescent — Fri, 27 Apr 2012 16:24:52 +0000

Vescent staff scientist Seth Johnson and engineer Neil Rebolledo recently realized ~20 nsec of control over optical time delays, with consistent optical throughput’s of greater than 90%; the time step resolution was ~250 psecs. To our knowledge this is the first time such large delays, with such high resolution step sizes and optical clarity have been demonstrated. The proprietary technique for this utilized a monolithic and compact structure that is amenable to hundreds or even thousands of optical channels. Applications include phased array radar, phased array antennas, and other RF photonics.

Cold atom work from Vescent scientist published in PRL

vescent — Fri, 27 Apr 2012 16:05:42 +0000

Staff scientist Juan Pino recently has his work on “Measurements of Tan’s Contact in an Atomic Bose-Einstein Condensate” published Physical Review Letters. ” This was work he performed while in the groups of Deborah Jin and Eric Cornell at JILA. The article may be viewed here: http://link.aps.org/doi/10.1103/PhysRevLett.108.145305, DOI: 10.1103/PhysRevLett.108.145305

Visit the Vescent booth at CLEO 2012, booth #1639

vescent — Thu, 22 Mar 2012 16:53:11 +0000

Vescent will have a booth on the trade show floor at the 2012 CLEO conference. As usual, we will have a suite of demonstrations running, both for our long-running favorite ultra-stable cold atom laser systems and for new products. Stop by booth #1639 and talk with one of our scientists about how our technology can help your research or engineering efforts.

Vescent scientists presenting at 2012 DAMOP conference

vescent — Thu, 22 Mar 2012 16:47:29 +0000

Dr. Sarah Bickman and Dr. Juan Pino, both Vescent staff scientists, will be presenting posters at the 2012 DAMOP meeting. Dr. Bickman will be presenting new techniques to realize very compact and low power optical shutter systems for cold-atom based experiments. Dr. Pino will be presenting a new, atomically referenced lasers system that includes a rubidium refernce cell, master laser, and frequency offset locked laser; all of this in a small butter fly package. The DAMOP meeting will be held in Anaheim, CA from June 4th through 8th.

Vescent presenting at NRO technology seminar

vescent — Thu, 22 Mar 2012 16:36:33 +0000

VP of technology, Dr. Scott Davis, will be providing a technology seminar as part of an on-going series at the National Reconnaissance Office. The topic will be new techniques for realizing unprecedented optical time delays. He will present new results for realizing greater than 20 nanoseconds of tuning with optical throughputs greater than 90%.

Barbara “Bobbie” Sitzman joins Vescent admin. support

vescent — Tue, 20 Mar 2012 23:05:42 +0000

Ms. Sitzman has recently joined Vescent as a new full time employee. She is providing administrative and general office management support. Her years of small business office and business management experience are directly applicable to her duties at Vescent.

Vescent scientist Juan Pino featured in CPIA video

vescent — Tue, 20 Mar 2012 20:30:36 +0000

A new video touting the networking opportunities provided by CPIA has been released on YouTube. It was through CPIA that Vescent and Dr. Pino first connected, which directly lead to his employment; thanks! Please take a look at the video and continue to support Colorado photonics.

Vescent selected for NASA contract

vescent — Fri, 16 Mar 2012 00:01:48 +0000

NASA selected Vescent Photonics to execute a phase I SBIR in support of the upcoming ASCENDS mission. This mission will be the first to utilize satellite based laser spectroscopy with a goal of mapping global sources and sinks of atmospheric CO2. Vescent Photonics will be developing techniques for locking and controlling the laser frequencies.

Vescent awarded Air Force contract

vescent — Fri, 16 Mar 2012 00:01:27 +0000

Vescent Photonics was recently awarded a phase II SBIR contract from the Air Force Research Laboratories. Under this contract Vescent will design and build a new generation of lasers and electro-optics for new, cold-atom based, atomic sensors. Applications include revolutionary intertial sensors, clocks, gravimeters, and others.

Calculating Phase Noise from the D2-135

vescent — Wed, 11 Jan 2012 00:40:51 +0000

Q: What is the phase-noise on my laser beat-note going to look like when locked with the D2-135 Offset Phase Lock Servo (OPLS)?

A: There are a lot factors that affect the final lock performance of the D2-135. Like frequency noise, phase noise is measured in terms of a noise density — or noise within a frequency band: dBc/Hz. The “Hz” tells us the width of the frequency band is 1 Hz. The “c” in dBc is for “carrier” as dBc is the ratio of the power of the phase noise relative to the carrier. The density of noise will depend on the frequency and generally falls in to three distinct regimes:

High Frequency: The D2-135 servo loop will have some bandwidth. That bandwidth will depend on numerous factors, but primarily your laser and how you are adjusting your laser frequency. We’ve measured bandwidths as high as 3 MHz with the D2-135, but for the example here, let’s say your bandwidth is 100 kHz. For frequencies above 100 kHz, the D2-135 does nothing. Your phase noise at these frequencies is whatever your phase noise is on your lasers to begin with.
Loop Filter: This is where the D2-135′s servo loop is performing like a text-book servo system: the phase noise is reduced ~ 1/G where G is the loop gain. See Introduction to Servos Part 1 for more details. If our bandwidth is 100 kHz, and we have a single integrator at 100 kHz, then phase noise at 10kHz will be reduced by a factor of 10. Phase noise at 100 Hz will be reduced by 1,000. Please note that in most situations, the output of the D2-135 adjust as laser’s frequency, not phase, and when this is the case, the loop filter is not proportional to the poles set on the feedback of the D2-135.
Noise limit: At lower and lower frequencies, the servo reduces more and more phase noise until eventually it hits a phase-noise floor. At this point, the phase noise will remain constant when going to lower frequencies. The phase noise floor is typically set by either the D2-135′s phase noise floor, or the phase-noise on the frequency reference used. To determine the phase-noise floor, one must calculate both and use the larger number. The phase-noise floor of the D2-135 is given by the formula:

D2-135 Phase-Noise Floor = -213 + 20Log(N) + 10 Log(F_REF)

where N is the divider setting (8,16,32 or 64) and F_REFis Reference Frequency. When possible, use a lower N and a higher F_REFas this will lower your noise floor. As an example, say you want to lock to an offset of 4 GHz. You set N=32 and use the internal VCO reference (high mode) and tune the VCO until the Reference Frequency is 125 MHz (125 MHz * 32 = 4 GHz). Your noise limit is -213 +20*Log(32)+10*Log(125e6) = -102 dBc/Hz.

The noise floor from the VCO is the VCO’s own noise floor multiplied by N as the phase-noise on the reference gets multiplied up to the beat note frequency by the OPLS.

VCO Phase-Noise Floor = VCO Phase-Noise + 20Log(N)

In our example, the phase-noise from the VCO is 32 times, or 30dB, greater than the VCO’s phase-noise. Once both the VCO Phase-Noise Floor and the D2-135 Phase-Noise Floor has been calculated, use the larger value (or technically add them, but usually one term is much smaller than the other and can be ignored).