Simon C. Zeller

Nearly quantum-noise-limited timing jitter from miniature Er:Yb:glass lasers.

We havemeasured therelative timing jitter oftwopassively mode-locked 10-GHz Er:Yb:glass lasers tobe190fs(100Hz-1.56 MHz)infree-running and26fs(6Hz-1.56 MHz) insynchronized operation. Wepresent theresults oftiming jitter measurements fortwopassively mode-locked 10-GHzEr:Yb:glass lasers (Time- Bandwidth Products ERGO PGL).Thecavities arebuilt withgreat careformechanical stability andadditionally enclosed inametal case.Thelasers produce ;15mW ofaverage output power(fiber coupled) in1.5-ps Gaussian pulses. Thetiming ofthepulses relative tothat ofanexternal reference oscillator canbestabilized withaphase-locked loop which controls thecavity length bymoving anendmirror mounted onapiezo actuator. Tomeasure therelative timing jitter ofthetwolasers, weuseanindirect phase comparison method(l) that allows precise jitter measurements forfree-running ortiming-stabilized mode-locked lasers. Thefigure shows measured two- sided timing phase noise powerspectra ofthefree-running andthetiming-stabilized lasers. Eachcurve represents the average offoursingle measurements with ameasurement timeof0.17s.Thedashed line showsthelimit given by quantum noise sources inthecavities.(2)

Broad multiwavelength source with 50 GHz channel spacing for wavelength division multiplexing applications in the telecom C band

We present a multiwavelength source with a spectral width of 42 nm at -20 dB. The frequency comb is generated by spectrally broadening the output of an amplified 50 GHz Er:Yb:glass laser with a highly nonlinear photonic crystal fiber. After spectral flattening the comb covers 37 channels with 5.4 mW average power per channel, and locking only one central wavelength channel to the International Telecommunication Union grid results in a maximum frequency error of 0.24% for all channels.

Compact Er:Yb:glass-laser-based supercontinuum source for high-resolution optical coherence tomography

We present a low coherence light source by direct super-continuum generation from a diode-pumped, passively modelocked Er:Yb:glass-laser, which generates 198 fs transform-limited pulses with an average power of 100 mW at a repetition rate of 75 MHz. The pulse train is launched into a dispersion optimized highly nonlinear fiber for spectral broadening. The optical bandwidth spans from 1150 nm to 2400 nm, which is more than one octave. The potential for ultrahigh-resolution optical coherence tomography (OCT) is demonstrated by coherence measurements supporting an axial resolution of 3.5 microm in air.

Frequency comb generation with 50-GHz channel spacing in the telecom C-band

We present a frequency comb with a spectral width of 43 nm at -20 dB. This comb was generated by spectrally broadening the output of an amplified 50-GHz Er:Yb:glass laser with a highly nonlinear fiber.

Nearly quantum noise limited timing jitter from miniature Er:Yb:glass lasers

We have measured the relative timing jitter of two passively mode-locked 10-GHz Er:Yb:glass lasers to be 190 fs (100 Hz-1.56 MHz) in free-running and 26 fs (6 Hz-1.56 MHz) in synchronized operation.

Antimonide semiconductor saturable absorber for passive mode locking of a 1.5-/spl mu/m Er : Yb : glass laser at 10 GHz

We demonstrate the first antimonide (AlGaAsSb) semiconductor saturable absorber mirror (SESAM) for stable passive mode locking of an Er : Yb : glass laser at 10 GHz and a center wavelength of 1535 nm generating 4.7-ps pulses. The nearly resonant SESAM is InP-based, grown by metal-organic vapor phase epitaxy and optimized for high pulse repetition rates. We fully characterized the linear and nonlinear optical parameters: The saturation fluence is 80 /spl mu/J/cm/sup 2/, the modulation depth is 0.4% and the nonsaturable losses are 0.35%. A 1/e decay time of 95 ps is achieved after wet chemical etching of the 10-nm InP cap on top of the absorber.

Fiber-Broadened Passively Modelocked Er: Yb: Glass Laser for High-Resolution Optical Coherence Tomography

We demonstrate a low coherence light source by directly launching the output of a femtosecond diode-pumped modelocked Er:Yb:glass laser into a highly-nonlinear fiber. The measured interferogram supports a depth resolution of 4 mum in air.

Moving towards 100 GHz from a passively mode-locked Er:Yb:glass laser at 1.5 μm

This paper presents a system, which allows extending the operation range into the 100-GHz regime. The approach is based on fundamental mode locking i.e. a single pulse is circulating in the laser cavity thus avoiding the instabilities and timing jitter which typically arise from harmonic modelocking. For 100 GHz, this leads to an extremely small optical cavity length of 1.5 mm for a linear standing wave cavity.

Octave spanning supercontinuum from compact passively mode-locked Er:Yb:glass laser

By using a recently developed nonlinear fiber, we achieve octave-spanning spectrum directly from a diode-pumped passively mode-locked 250-fs Er:Yb:glass laser without any amplification stage. Applications for CEO phase stabilization and optical clocking are discussed.

Novel 10- to 40-GHz Telecom Pulse Generating Sources with High Average Power

As data transmission rates continue to increase, pulsed lasers are becoming increasingly important for telecom applications. Novel transmission systems at 10 Gb/s and higher often use return-to-zero (RZ) formats [1,2] and soliton dispersion management techniques [3, 4], which both rely on clean optical pulses. Therefore, these approaches benefit greatly from the availability of simple, compact, and efficient optical pulse generators. There are many compelling reasons to use a pulsed laser directly as a source in the transmitter of optical telecommunication systems, rather than an externally modulated continuous-wave (cw) source. First, they eliminate the need for a high-end modulator to create the pulses and thereby simplify system architecture, increase efficiency, and reduce cost. Secondly, the contrast ratio of pulsed lasers is typically much higher than for modulated cw sources. This improves system signal-to-noise and allows further scaling to higher repetition rates through optical time-division multiplexing (OTDM). Apart from the transmitter side, there are interesting applications of pulsed lasers also in the receivers of transmission systems, e.g. for demultiplexing and clock recovery [5-7]. Furthermore, applications outside the telecom area, in the fields of optical clocking [8, 9], high-speed electro-optic sampling [10,11], frequency metrology (similar to the work presented in Ref. 12) or generation of polarized electron beams for particle accelerators 13 become increasingly important.