


2020-01-27
DANIEL SÁNCHEZ PEACHAM
DANIEL SÁNCHEZ PEACHAM

2020-01-31
CHRISTOS CHARALAMBOUS
CHRISTOS CHARALAMBOUS

2020-02-06
SERGIO LUCIO DE BONIS
SERGIO LUCIO DE BONIS

2020-02-10
JULIO SANZ SÁNCHEZ
JULIO SANZ SÁNCHEZ

2020-02-17
SANDRA DE VEGA
SANDRA DE VEGA

2020-02-21
ESTHER GELLINGS
ESTHER GELLINGS

2020-03-26
NICOLA DI PALO
NICOLA DI PALO

2020-03-30
ANGELO PIGA
ANGELO PIGA

2020-04-24
PABLO GOMEZ GARCIA
PABLO GOMEZ GARCIA

2020-06-04
ANUJA ARUN PADHEY
ANUJA ARUN PADHEY

2020-06-08
VIKAS REMESH
VIKAS REMESH

2020-06-23
DAVID ALCARAZ
DAVID ALCARAZ

2020-06-30
GERARD PLANES
GERARD PLANES

2020-07-09
IRENE ALDA
IRENE ALDA

2020-07-13
EMANUELE TIRRITO
EMANUELE TIRRITO

2020-07-16
ALBERT ALOY
ALBERT ALOY

2020-07-27
MARIA SANZ-PAZ
MARIA SANZ-PAZ

2020-07-28
JUAN MIGUEL PÉREZ ROSAS
JUAN MIGUEL PÉREZ ROSAS

2020-10-08
ZAHRA RAISSI
ZAHRA RAISSI

2020-10-30
IVAN BORDACCHINI
IVAN BORDACCHINI

2020-11-09
GORKA MUÑOZ GIL
GORKA MUÑOZ GIL

2020-11-17
ZAHRA KHANIAN
ZAHRA KHANIAN

2020-11-27
PAMINA WINKLER
PAMINA WINKLER
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2020-12-02
BIPLOB NANDY
BIPLOB NANDY
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2020-12-11
DANIEL GONZÁLEZ CUADRA
DANIEL GONZÁLEZ CUADRA
Novel Continuous-Wave Infrared Parametric Sources and Noise Analysis of Infrared Upconversion Detectors


Dr Anuja Padhye
June 4th, 2020
ANUJA ARUN PADHEY
Optical Parametric Oscillators
ICFO-The Institute of Photonic Sciences
The ability to manipulate frequency of light, through parametric frequency conversion sources based on χ(2) nonlinear materials, offers an effective route to spectral regions unapproachable by conventional lasers. Most importantly, three-wave mixing processes provide tunable coherent radiation over a broad spectral range. Among the most important tunable devices, narrow linewidth continuous-wave (cw) infrared (IR) optical parametric oscillators (OPOs) are indispensable excitation sources for many applications in molecular spectroscopy and precision metrology. In order to exploit such applications, the development of cw OPOs deploying different wavelength tuning schemes and novel nonlinear materials is highly dezirable, as presented in this thesis. We demonstrated a rapidly tunable cw OPO based on fan-out grating design periodically-poled KTiOPO4 (PPKTP) crystal at room temperature. This approach allows continuous wavelength tuning by avoiding increased thermal fluctuations at higher operating crystal temperatures. The 532 nm-pumped, output-coupled singly-resonant oscillator (OC-SRO) provides widely tunable near-IR radiation across 741-922 nm and 1258-1884 nm, with total output power of 1.65 W. The use of output coupling for the resonating wave reduces thermal loading and enables 30% enhancement in the OPO extraction efficiency over the pure SRO configuration. Towards the goal of developing a next-generation cw source >4 μm using a new found quasi-phase-matched semiconductor material, orientation-patterned gallium phosphide (OP-GaP), we demonstrated the first realization of a tunable cw mid-IR source based on OP-GaP by exploiting single-pass difference-frequency-generation (DFG) between a Tm-fiber laser at 2010 nm and a home-built OPO based on MgO-doped periodically-poled LiNbO3 (MgO:PPLN) crystal. The DFG source generates up to 43 mW of output power, with >30 mW across 96% of the tuning range 4608-4694 nm, in high beam quality. As the tunable mid-IR sources are making great strides, the availabilityof fast and sensitive mid-IR detectors become equally important. However, the conventional mid-IR detectors demand cryogenic systems for low-noise operation which sets a major drawback as these devices are often bulky and expensive. In this context, the nonlinear frequency upconversion technique has emerged as a promising alternative to the direct detection of mid-IR radiation at room temperature. An upconversion detector (UCD) can be further optimized by identifying and suppressing its noise sources. In order to do so, we experimentally and theoretically investigated noise properties of 1064 nm-pumped single-pass UCD designed for signal detection in telecom and mid-IR range using MgO:PPLN crystals. We studied the dependence of newly discovered SHG (532 nm)-induced spontaneous parametric downconversion (SHG-SPDC) noise intensity on the pump power and crystal temperature, and compared it with the well-known UCD noise source upconverted spontaneous parametric downconversion (USPDC). The measurements deduce that SHG-SPDC must be given a careful consideration since it can act as a dominant noise source under certain operating conditions. However, SHG-SPDC can be avoided by choosing a proper combination of MgO:PPLN grating period,operating temperature, and bandpass filter.
Thursday, June 4, 2020, 16:00. Online
Thesis Advisor: Prof Dr Majid Ebrahim-Zadeh
ICFO-The Institute of Photonic Sciences
The ability to manipulate frequency of light, through parametric frequency conversion sources based on χ(2) nonlinear materials, offers an effective route to spectral regions unapproachable by conventional lasers. Most importantly, three-wave mixing processes provide tunable coherent radiation over a broad spectral range. Among the most important tunable devices, narrow linewidth continuous-wave (cw) infrared (IR) optical parametric oscillators (OPOs) are indispensable excitation sources for many applications in molecular spectroscopy and precision metrology. In order to exploit such applications, the development of cw OPOs deploying different wavelength tuning schemes and novel nonlinear materials is highly dezirable, as presented in this thesis. We demonstrated a rapidly tunable cw OPO based on fan-out grating design periodically-poled KTiOPO4 (PPKTP) crystal at room temperature. This approach allows continuous wavelength tuning by avoiding increased thermal fluctuations at higher operating crystal temperatures. The 532 nm-pumped, output-coupled singly-resonant oscillator (OC-SRO) provides widely tunable near-IR radiation across 741-922 nm and 1258-1884 nm, with total output power of 1.65 W. The use of output coupling for the resonating wave reduces thermal loading and enables 30% enhancement in the OPO extraction efficiency over the pure SRO configuration. Towards the goal of developing a next-generation cw source >4 μm using a new found quasi-phase-matched semiconductor material, orientation-patterned gallium phosphide (OP-GaP), we demonstrated the first realization of a tunable cw mid-IR source based on OP-GaP by exploiting single-pass difference-frequency-generation (DFG) between a Tm-fiber laser at 2010 nm and a home-built OPO based on MgO-doped periodically-poled LiNbO3 (MgO:PPLN) crystal. The DFG source generates up to 43 mW of output power, with >30 mW across 96% of the tuning range 4608-4694 nm, in high beam quality. As the tunable mid-IR sources are making great strides, the availabilityof fast and sensitive mid-IR detectors become equally important. However, the conventional mid-IR detectors demand cryogenic systems for low-noise operation which sets a major drawback as these devices are often bulky and expensive. In this context, the nonlinear frequency upconversion technique has emerged as a promising alternative to the direct detection of mid-IR radiation at room temperature. An upconversion detector (UCD) can be further optimized by identifying and suppressing its noise sources. In order to do so, we experimentally and theoretically investigated noise properties of 1064 nm-pumped single-pass UCD designed for signal detection in telecom and mid-IR range using MgO:PPLN crystals. We studied the dependence of newly discovered SHG (532 nm)-induced spontaneous parametric downconversion (SHG-SPDC) noise intensity on the pump power and crystal temperature, and compared it with the well-known UCD noise source upconverted spontaneous parametric downconversion (USPDC). The measurements deduce that SHG-SPDC must be given a careful consideration since it can act as a dominant noise source under certain operating conditions. However, SHG-SPDC can be avoided by choosing a proper combination of MgO:PPLN grating period,operating temperature, and bandpass filter.
Thursday, June 4, 2020, 16:00. Online
Thesis Advisor: Prof Dr Majid Ebrahim-Zadeh