Systems And Methods For Long-Range, High-Resolution Laser Radar Range Detection

Provided are systems and methods for long-range, high-resolution, laser radar range detection. In one embodiment such a system includes an optical pulse modifier configured generated a stretched optical pulse and an optical amplifier configured to increase an optical power of the stretched optical pulse The system can further include an optical spectrum analyzer configured to determine a wavelength of a spectral peak that results from interference between a first amplified stretched pulse that is reflected from a target and a second amplified stretched pulse that is spectrally reversed

Picosecond Pulse Generation Using A Saturable Absorber Section Of Grating-Coupled Surface-Emitting Laser

We report on a passively and hybridly mode-locked grating-coupled surface-emitting laser (GCSEL) using the unpumped section of the GCSEL as a saturable absorber. We obtain 8.8-ps full-width at half-maximum (FWHM) autocorrelation pulses in passive mode-locked operation and an FWHM pulse duration of 3.4 ps in hybrid mode-locked operation, which are the shortest pulses from a GCSEL external cavity. With hybrid mode-locking, a peak power of 0.26 W and a spectral bandwidth of 0.6 nm are obtained. These results demonstrate the potential of multisegment GCSELs in ultrashort pulse generation. © 2005 IEEE

Actively Mode-Locked Grating Coupled Surface Emitting Semiconductor Laser (Gcsel)

An external cavity, actively mode-locked grating coupled surface emitting semiconductor laser (GCSEL) is demonstrated for the first time. The pulse width from the oscillator is 27 ps and its optical spectrum bandwidth is 0.07 nm at 975.9 nm. ©2002 Optical Society of America

Passive And Hybrid Modelocking Of A Grating-Coupled Surface-Emitting Laser (Gcsel)

We report the first passive and hybrid modelocking of a grating-coupled surface-emitting laser (GCSEL), exploiting the unpumped grating section of the GCSEL as a saturable absorber to generate short pulses, is demonstrated. Pulsewidths 2.8psec with 1.1nm bandwidth at 980nm are obtained ©2005 Optical Society of America

Extreme Chirped Pulse Amplification (X-Cpa) Using Semiconductor Gain Media

The concept of X-CPA using a semiconductor gain media with \u3c1ns energy storage lifetime and CFBG with large dispersion is introduced. The pulse stretching and recompression is demonstrated with a pair of CFBGs (2000ps/nm). In addition, the gain saturation behavior without and with pulse stretching is demonstrated experimentally and numerically. The results showed that future high pulse energy, ultrafast mode-locked laser systems will be achievable from an all-semiconductor gain media platform

Generation Of 238Nj, 16Ns Stretched Pulses In All Semiconductor X-Cpa System

The generation of 238nJ stretched pulses in an XCPA system has been achieved prior to a pulse compression stage. The total system gain is 41 dB. Using one CFBG, 1.62ps pulse is stretched over 4000 times and recompressed back to 1.80ps

Extreme Chirped Pulse Modelocked Diode Laser Ring Oscillator Using A Theta Cavity Design

We demonstrate an extreme chirped pulse modelocked laser, simultaneously generating near-transform-limited 3.6 psec optical pulses and a 510 psec linearly chirped output. The design overcomes fundamental limitations of energy extraction and nonlinearities induced by gain dynamics. High energy short pulse lasers play important roles in industry including remote sensing and material processing. Even though the semiconductor laser has many attractive advantages, such as compactness, mass productivity, cost effectiveness and excellent wall-plug efficiency, the use of semiconductor lasers in high power applications has been limited by their small energy storage time, as compared to other gain mediums. However, most recently, we have developed the extreme chirped pulse amplification system that generates 1.4 kW of peak power from an all-semiconductor master oscillator and power amplifier (MOPA) system to overcome the small energy storage time of semiconductor lasers [1], This summary describes a novel extreme chirped pulse laser oscillator that generates a periodic linearly chirped cw ouput and ultrashort pulses, simultaneously. One of key advantages of this laser system is the absence of self-phase modulation in the semiconductor optical amplifier (SOA). In this operation regime, the modelocked pulses are temporally stretched to a temporal duration that equals the pulse repetition period, converting the pulse train into a cw signal. By amplifying this cw signal in the semiconductor optical amplifier, the detrimental effects of transient gain saturation and integrating self phase modulation are eliminated [2, 3]. Recently, a \u27free-space\u27 breathing mode dispersion managed modelocked diode ring laser has been demonstrated, that uses the ideas of intracavity temporal pulse shape management to minimize nonlinearities in the semiconductor gain [4, 5]. The extreme chirped pulse modelocked oscillator is an evolution of the dispersion managed oscillator, but with a new key advantage. The pulse repetition period of the modelocked oscillator can be adjusted to be longer that the gain recovery time. In this case, since the gain dynamics of the SOA behaves in the cw regime, the limitation to the extracted pulse energy under transient optical amplification can be overcome. As a result, the output power of the laser can be increase by increasing the DC current, without concern of the gain saturation and nonlinearities induced by the transient gain dynamics. Finally, the present embodiment is comprised of all fiber components, providing compactness, and facilitating its use. The theta laser schematic is shown in Fig. 1. An SOA is inserted in an external cavity incorporating a chirped fiber bragg grating (CFBG), having a dispersion of 340 ps/nm, and a 20 GHz modulator. The single CFBG is used as a stretcher and a compressor in order to minimize the total group delay ripple. We use a low loss 20 GHz modulator and a tunable band pass filter having 5 nm FWHM to prevent a closed loop cw lasing of transmitted power. A 50 GHz electrical comb source is utilized to provide a short time window in active modelocking. The electrical pulse is amplified by use of a broadband modulator driver to achieve a sufficient modulation index. The laser is modulated at 1.951 GHz, generating periodic pulses separated by 510 psec. To demonstrate the operation of the modelocked oscillator, Fig. 2 shows low resolution spectrally resolved streak camera traces from the two different output ports of the laser. Fig. 2 (a) shows the spectrogram of the output port that generates modelocked pulses. Well defined pulses are observed with a pulse period of 510 psec. Fig. 2 (b) shows the output from the port that generates the periodic linearly chirped cw signal. Note in this figure, the true cw nature of the output. To obtain a more accurate measure of the temporal and spectral characteristics, Fig. 3 shows a sampling scope trace, an intensity autocorrelation and optical spectrum. The sampling scope trace (Fig. 3 (a)) shows resolution limited optical pulses separated at 510 psec. Fig. 3 (b, c) show the intensity autocorrelation trace and the optical spectrum measured at the three different DC bias currents to the SOA. The generated optical pulses are near the transform limited, with a pulse duration of 3.6 psec (FWHM) and a spectral bandwidth of 1.5 nm. Note that the pulse quality and optical spectrum maintain their general characteristics spanning a pumping current range of -4X the threshold current. In conclusion, we demonstrate a novel optical cavity design to realize an extreme chirped pulse modelocked laser. The novel ring, or theta cavity, generates near transform limited 3.6 psec modelocked optical pulses and a periodic 510 psec linearly chirped cw output, spanning 1.5 nm. The novel cavity design is used to overcome the limited energy extraction and nonlinearities induced by the transient gain dynamics in modelocked semiconductor lasers. In this experiment, we get 13.3 mW of average power at 600 mA in stretched port. These results show the extreme chirped pulse modelocked laser for the potential use of a master oscillator in high power applications. © 2005 IEEE

Extreme Chirped Pulse Oscillator (Xcpo) Using A Theta Cavity Design

We demonstrate an extreme chirped pulse mode-locked laser, simultaneously generating near-transform-limited 3.9-ps optical pulses and ∼510-ps linearly chirped output from the oscillator. The design overcomes fundamental limitations of energy extraction and nonlinearities induced by gain dynamics so that we can increase the dc current of the semiconductor optical amplifier up to 600 mA without distortion of the pulse characteristics. The maximum average power of the stretched pulses from the 1.95-GHz harmonically mode-locked semiconductor laser is measured to be 13.4 mW at 600 mA. © 2006 IEEE

External Cavity, Actively Mode-Locked Gcsel And Amplification Characteristics Of Gcsoa(Grating Coupled Surface Emitting Semiconductor Optical Amplifier)

Catastrophic optical damage on the emitting surface of a Fabry-Perot semiconductor laser is one of the key limitations in the generationof high output power from these devices. One method to avoid the catastrophic failure is to enlarge the emission area. Owing to a large emission area, the Grating Coupled Surface Emitting laser (GCSEL) has the potential to generate higher output power as compared to conventional edge emitting semiconductor lasers, by avoiding catastrophic facet damage. This paper demonstrates an external cavity, active mode-locked GCSEL and amplification characteristics of GCSOA using a c.w. external cavity GCSEL

Passive And Hybrid Modelocking Of A Grating-Coupled Surface-Emitting Laser (Gcsel)

We report the first passive and hybrid modelocking of a grating-coupled surfaceemitting laser (GCSEL), exploiting the unpumped grating section of the GCSEL as a saturable absorber to generate short pulses, is demonstrated. Pulsewidths 2.8psec with 1.1nm bandwidth at 980nm are obtained. © 2005 Optical Society of America