Danielle Braje

Astronomical spectrograph calibration with broad-spectrum frequency combs

Abstract.Broadband femtosecond-laser frequency combs are filtered to spectrographically resolvable frequency-mode spacing, and limitations of using cavities for spectral filtering are considered. Data and theory are used to show implications relevant to spectrographic calibration of high-resolution, astronomical spectrometers.

Improved signal-to-noise ratio of 10 GHz microwave signals generated with a mode-filtered femtosecond laser frequency comb

We use a Fabry-Perot cavity to optically filter the output of a Ti:sapphire frequency comb to integer multiples of the original 1 GHz mode spacing. This effectively increases the pulse repetition rate, which is useful for several applications. In the case of low-noise microwave signal generation, such filtering leads to improved linearity of the high-speed photodiodes that detect the mode-locked laser pulse train. The result is significantly improved signal-to-noise ratio at the 10 GHz harmonic with the potential for a shot-noise limited single sideband phase noise floor near -168 dBc/Hz.

Generation of 20 GHz, sub-40 fs pulses at 960 nm via repetition-rate multiplication

Optical filtering of a stabilized 1 GHz optical frequency comb produces a 20 GHz comb with approximately 40 nm bandwidth (FWHM) at 960 nm. Use of a low-finesse Fabry-Pérot cavity in a double-pass configuration provides a broad cavity coupling bandwidth (Deltalambda/lambda approximately 10%) and large suppression (50 dB) of unwanted modes. Pulse durations shorter than 40 fs with less than 2% residual amplitude modulation are achieved.

Remote sensing and control of phase qubits

We demonstrate a remote sensing design of phase qubits by separating the control and readout circuits from the qubit loop. This design improves measurement reliability because the control readout chip can be fabricated using more robust materials and can be reused to test different qubit chips. Typical qubit measurements such as Rabi oscillations, spectroscopy, and excited-state energy relaxation are presented.

Self-Referenced and Optically Stabilized 10 GHz Frequency Comb

We demonstrate a self-referenced 10 GHz Ti:sapphire frequency comb where the continuum is generated in microstructured fiber. In addition, we discuss optical stabilization of the comb via saturated absorption in87Rb with a single mode.

Toward Ultrafast Optical Waveform Synthesis with a Stabilized Ti:Sapphire Frequency Comb

We have developed a system for line-by-line control of a stabilized Ti:Sapphire optical frequency comb. We show individually-addressed 20 GHz comb modes around 960 nm and apply simple masks to demonstrate individual mode control.

Generation of sub-40 fs Pulses at 20 GHz via Repetition Rate Multiplication

Optical filtering of a stabilized 1 GHz optical frequency comb produces a 20 GHz comb with ~40 nm bandwidth (FWHM) at 960 nm. Pulse durations <40 fs with low residual amplitude modulation are achieved.

Time and frequency filtering of optical combs

Fabry-Perot cavity filtering of broadband optical frequency combs is studied experimentally and theoretically. Effects of dispersion, mirror coatings, and carrier envelope offset frequency are analyzed while highlighting applications to waveform generation and spectroscopic references.