Characterization of Thermal Frequency Modulation of a DFB Laser Using Digital Coherent Detection

2016 ◽  
Author(s):  
Feng Yuan ◽  
Di Che ◽  
Qian Hu ◽  
William Shieh
Keyword(s):  
Frequency Modulation ◽  
Coherent Detection ◽  
Dfb Laser

Spectral characterization of integrated acousto-optic tunable filters by means of laser frequency modulation spectroscopy

2006 ◽  
Vol 45 (36) ◽  
pp. 9176 ◽  
Author(s):  
Antonio Di Maio ◽  
Mario Salza ◽  
Gianluca Gagliardi ◽  
Pietro Ferraro ◽  
Paolo De Natale
Keyword(s):  
Frequency Modulation ◽  
Laser Frequency ◽  
Tunable Filters ◽  
Spectral Characterization ◽  
Modulation Spectroscopy ◽  
Laser Frequency Modulation

scholarly journals Characterization of InGaN/GaN-Based Multi-Quantum Well Distributed Feedback Lasers

1998 ◽  
Vol 537 ◽  
Author(s):  
Daniel Hofstetter ◽  
Robert L. Thornton ◽  
Linda T. Romano ◽  
David P. Bour ◽  
Michael Kneissl ◽  
...  
Keyword(s):  
Ion Beam ◽  
Device Fabrication ◽  
Distributed Feedback ◽  
Coupling Scheme ◽  
Optically Pumped ◽  
Ion Beam Etching ◽  
Measurement Results ◽  
Dfb Laser ◽  
First Time

AbstractWe present a device fabrication technology and measurement results of both optically pumped and electrically injected InGaN/GaN-based distributed feedback (DFB) lasers operated at room temperature. For the optically pumped DFB laser, we demonstrate a complex coupling scheme for the first time, whereas the electrically injected device is based on normal index coupling. Threshold currents as low as 1. 1 A were observed in 500 μm long and 10 μm wide devices. The 3rd order grating providing feedback was defined holographically and dry-etched into the upper waveguiding layer by chemically-assisted ion beam etching. Even when operating these lasers considerably above threshold, a spectrally narrow emission (3.5 Å) at wavelengths around 400 nm was seen.

scholarly journals Characterization of Nucleobases in Broadband Terahertz Spectra from 0.5 to 10 THz with the Air-Biased-Coherent-Detection Technique

Sensors ◽  
2019 ◽  
Vol 19 (5) ◽  
pp. 1148 ◽  
Author(s):  
Miao Yu ◽  
Shihan Yan ◽  
Yong-qiang Sun ◽  
Wang Sheng ◽  
Fu Tang ◽  
...  
Keyword(s):  
Low Frequency ◽  
Frequency Region ◽  
Coherent Detection ◽  
Detection Technique ◽  
Terahertz Time Domain Spectroscopy ◽  
High Frequency Region ◽  
Characteristic Absorption ◽  
Thz Range ◽  
Thz Absorption

Terahertz time-domain spectroscopy (THz-TDS) is an effective coherent detection technique for deeply understanding the structures and functions of biomolecules. However, generally not full information in the whole THz range can be obtained due to the limited detection bandwidth (usually less than 5 THz) of the traditional THz-TDS systems. In this paper, effective THz absorption spectra in 0.5–10 THz range of five typical nucleobases of DNA/RNA are characterized with a super broadband THz detection technique, called the air-biased- coherent-detection (THz-ABCD) technique. Few unexpected characteristic absorption peaks appeared in the low-frequency region and meanwhile a series of anticipated characteristic absorption peaks are found in the high-frequency region. The fingerprint spectra of these nucleobases are helpful for further analysis on the vibration and twisting behavior of hydrogen bonds, van der Waals and electrostatic forces etc. between and within DNA/RNA biomolecules.

Microfluidic serpentine antennas with designed mechanical tunability

Lab on a Chip ◽  
2014 ◽  
Vol 14 (21) ◽  
pp. 4205-4212 ◽  
Author(s):  
YongAn Huang ◽  
Yezhou Wang ◽  
Lin Xiao ◽  
Huimin Liu ◽  
Wentao Dong ◽  
...  
Keyword(s):  
Frequency Modulation ◽  
Mechanical Tunability

This paper describes the design and characterization of microfluidic serpentine antennas with reversible stretchability and designed mechanical frequency modulation (FM).

On the Characteristics of Bifurcation and Nonlinear Dynamic Response

2004 ◽  
Vol 126 (4) ◽  
pp. 574-579 ◽  
Author(s):  
Baozhong Yang ◽  
C. Steve Suh
Keyword(s):  
Spectral Analysis ◽  
Dynamic Response ◽  
Amplitude Modulation ◽  
Frequency Modulation ◽  
Instantaneous Frequency ◽  
Dynamic Instability ◽  
Spectral Component ◽  
The Individual

Spectral analysis has been widely applied to the detection of bifurcation and the determination of the extent to which dynamic instability and chaotic responses develop. However, because spectral analysis employs stationary sinusoids in representing time-varying signals of inherent nonlinearity, the use of Fourier domain methodologies would inexorably risk misinterpreting the true characteristics and obscuring the underlying physics of the nonlinear system being investigated. The fact that the amplitude and frequency of all the individual spectral component of a nonlinear, nonstationary dynamic response are modulated and coupled in time necessarily implies that, if the inception and transition of a bifurcated state of unstable motion is to be fully characterized, amplitude modulation and frequency modulation need to be temporally decoupled. The fundamental notion of instantaneous frequency defines frequency as the temporal gradient of phase and thus provides a powerful mechanism through which amplitude modulation and frequency modulation can be disassociated. Results of applying instantaneous frequency to the characterization of bifurcation and evolution of instability for a cracked rotor also indicate that instantaneous frequency interprets nonlinear rotary responses with sound physical bases.

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