Pulsed Semiconductor Laser Research Articles

Propagation of chirped semiconductor laser pulses in monomode fibers

A basic result for the dynamic behavior of semiconductor lasers is combined with the propagation properties of optical fibers. The frequency chirp observed when a semiconductor laser is modulated gives an enhanced time–bandwidth product. Pulse compression due to fiber dispersion is shown to be directly related to the laser properties.

Measurement of picosecond semiconductor laser pulse duration with internally generated second harmonic emission

We demonstrate a simple practical technique for the measurement of the duration of picosecond semiconductor laser pulses using the internally generated second harmonic emission accompanying the laser output. The pulse duration is determined by the ratio of the conversion efficiencies of the second harmonic emission generated by the picosecond pulses and by the cw emission or other pulsed emission whose duration can be accurately measured. The pulse duration thus measured is in close agreement with that determined by the nonlinear intensity autocorrelation technique.

Pulsed multielement semiconductor laser with an unstable resonator

A pulsed multielement semiconductor laser with an unstable resonator was made of cadmium sulfide. Narrowing of the angular distribution of the output radiation to 30' for an output power of 200 kW was achieved.

Pulsed semiconductor laser fluorometry for lifetime measurements

Lifetime measurement of a polymethine dye in various solvents utilizing a novel pulsed semiconductor laser in a time-correlated photon counting system is presented. A relationship between the fluorescence lifetime and solvent polarity is reported. 17 references, 3 figures.

Measurement of 1.3 and 1.55 μm gain-switched semiconductor laser pulses with a picosecond IR streak camera and a high-speed InGaAs PIN photodiode

Gain-switched semiconductor laser pulses at 1.3 and 1.55 μm were measured both with a high-speed InGaAs PIN photodiode and an IR synchroscan streak camera. Gain-switching characteristics and their bias dependence observed with both detection schemes are consistent with each other. Laser pulses of 24-30 ps duration are observed. Picosecond pulses from a gain-switched 1.55 μm DFB laser are found to be chirped but not transform-limited.

Production of short pulses in semiconductor lasers by external laser excitation through χ^(3)

It is shown that parametric mixing through chi((3)) of two injected laser lines can provide index modulation sufficient for the mode locking of the semiconductor laser. Numerical estimates indicate that picosecond pulses with 100-GHz repetition rates should be possible with a few watts of external laser power.

Exploitation of a Pulsed Laser to Explore Transient Effects on Semiconductor Devices

This paper sets out to demonstrate the use of a pulsed semiconductor laser facility as a laboratory prompt gamma simulator, to complement existing radiation simulators. Comparability has been established between results obtained on the Laser Simulator and LINAC on a device technology family basis. The ease with which measurements at elevated temperatures and small area searches can be made are addressed and limitations to its use are noted.

Streak camera study of short pulse generation in an optically pumped GaAs/(GaAl)As laser

A synchronously operated picosecond streak camera has been used in a direct time-resolved study of luminescence and laser emission from a GaAs/(GaAl)As double heterostructure laser pumped by <90 ps, 514-nm optical pulses from a mode-locked Ar ion laser. Semiconductor laser pulse widths down to 20 ps were recorded and the dependence of the temporal characteristics of these pulses on average pump power was investigated.

Generation of short optical pulses in semiconductor lasers by combined DC and microwave current injection

We report picosecond pulse generation in low threshold buried optical guide lasers using combined direct and microwave current excitation. The pulse widths were obtained as a function of direct current for several levels of RF excitation using lasers 125 and 380 μm long. The pulses have a Gaussian shape with full widths at half maximum intensity ranging from 19 to 57 ps. The pulse widths were obtained from the second harmonic autocorrelation. The experimental results are in reasonable agreement with the theory of short pulse formation in sinusoidally modulated lasers. The pulse width decreases with increasing dc and microwave current, and decreasing laser length. The shortest pulses were obtained with a 125μm long laser using 0.25 W RF at 1 GHz and 35 mA de bias. Multiple pulses are emitted at high dc excitation levels. Using the above laser at the indicated current levels the emission consists of a burst of ∼10 pulses which are separated by 30 ps, and has an approximately exponentially decaying amplitude. Saturable absorption was introduced in the lasers by degradation and results in shortening the pulses. A comparison is made of the pulse widths obtained for sinusoidal microwave current modulation and for pulsed excitation where the excitation is obtained from a step recovery diode. Reduced pulse widths are obtained for short current pulse excitation.

Use of semiconductor lasers in geodesic interference measurements of distances

A study was made of the use of semiconductor lasers in geodesic interference measurements of distances. Prototype experiments were carried out using a pulsed semiconductor laser operating at room temperature. The interferometer arms were equalized by determining the contrast maximum of the interference pattern on gradual reduction of the coherence length of the laser light source. The results indicated that it should be possible to simplify considerably the method and increase the precision of measurements of distances compared with the procedures employed at present.

Propagation of a semiconductor laser pulse in an optical fiber

Frequency modulation of the optical carrier, due to heating a p-n junction, is a characteristic feature of the injection laser radiation. This feature is allowed for in a calculation of the distortion of a pulse generated by such a laser and traveling in an optical fiber characterized by frequency dispersion. The optimal parameters of the fiber, corresponding to the maximum narrowing of the pulse, are determined.

A Technique of Modulating Pulsed Semiconductor Lasers

This paper gives details of the pulse-position modulation technique as applied in the case of a pulsed room-temperature-operated GaAs laser diode for communication purposes. The input analog signal is converted into a digital format and information transmission takes place through the laser pulses occurring at different positions in time. Special care is taken to synchronize the receiver with the transmitter. At the receiver the analog information is reconstructed. The technique can be incorporated in the development of a short-haul point-point-to-point voice communication system using the laser diode.