摘要:

The far-field patterns and the wavefronts of planar stripe-geometry GaAIAs/GaAs lasers, as well as their variation with pumping current, have been investigated with the help of apparatus based on the Michelson interferometer. Experimental results were compared to the theoretical model of the planar stripe-geometry heterostructure injection laser, using a dielectrical slab and Epstein layer. The effect of kinks in the output (light/current) characteristics on the laser wavefront was studied.

DOI:10.1049/ip-j.1985.0013

出版商:IEE    

年代:1985

数据来源: IET

摘要:

Experimental investigations have been performed on the frequency characteristics and the dynamic V/I characteristics of the GaAs/GaAlAspn-pnnegative resistance laser designed by the authors. The turn-on and turn-off properties of the device are analysed based on the charge-storage theory and the double-transistor model, which is in good agreement with the measured results. It is shown that, with an applied forward bias larger than the turn-on voltage, the self oscillation stimulated emission frequency is primarily determined by the charge storage in the two bases. The achievable self-oscillation stimulated emission frequency is up to 15 MHz. However, it is predicted that a much higher frequency can be obtained by improving the design in order to lower the turn-on voltage and to enhance the holding current.

DOI:10.1049/ip-j.1985.0014

出版商:IEE    

年代:1985

数据来源: IET

摘要:

Optically excited (Ga, In, As, P) film lasers at 1.3 and 1.5 µm have been investigated. The lasers showed single-mode emission and a tuning range of up to 160 nm. The laser thresholdPtand the differential quantum efficiency ηDhave been investigated in resonators with different reflectivities. Optimum results (Pt= 100 MW/cm2, ηD= 2, 5%) have been achieved in an asymmetric resonator withR1= 0.92,R2= 0.75. An upper limit for the carrier density during excitation ofn≤ 1.1919cm−3is estimated from near-field measurements.

DOI:10.1049/ip-j.1985.0015

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The semiconductor Raman laser using the longitudinal optical phonon mode of GaP has a very low threshold value of optical input power. To reduce the threshold optical input power and power density further, a crystal as thin as 160 µm with a wave-guiding structure is used. Epitaxial layers of GaP with a thickness of 280 µm are demonstrated as the low-threshold semiconductor Raman laser, for which the threshold input power density is as low as 1.7 × 106W/cm2.

DOI:10.1049/ip-j.1985.0016

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The description of optical switching occurring at a Hopf bifurcation in semiconductor lasers is developed utilising a canonical transformation of the equations of laser dynamics. In canonical form, the equations of motion give an immediate identification of the switching frequency. It is further shown that the canonical transformation leads to a compact formalism for studying the stability of the oscillations established at the Hopf bifurcation.

DOI:10.1049/ip-j.1985.0017

出版商:IEE    

年代:1985

数据来源: IET

摘要:

Hysteresis and high quantum efficiency have been observed in the light-output/injection-current characteristics of a twin-diode external cavity ring laser. The diodes are GaAs/GaAlAs double heterostructure, 20 µm oxide stripe devices, AR coated and symmetrically placed in the ring. Under certain conditions the output in the bistable region became unstable, and slow, regular oscillations were observed. With increasing drive, this oscillatory behaviour became more irregular and eventually degenerated to chaos. We propose nonlinear effective self-focusing by the mutual action of the counterpropagating beams, in the ring laser as a possible mechanism to explain the effects observed.

DOI:10.1049/ip-j.1985.0018

出版商:IEE    

年代:1985

数据来源: IET

摘要:

For long-haul optical communications systems, the inverted rib waveguide (IRW) laser and its associated bonding technologies were chosen to give the highest possible reliability. Extensive lifetest studies have led to an endurance screen for wafers within 1500 hours to select wafers for further processing. Lifetests at 20, 50 and 150°C have shown an apparent activation energy of 0.25 eV for passed wafers and 0.51 eV for reject wafers. Passed wafers give a median change of threshold current in 25 years of 7% at 50°C, based on extrapolations of lifetest data from 1000 to 15 000 hours. The results support the view that the intrinsic degradation of good quality GalnAsP lasers occurs at an extremely low rate with low activation energy. More rapidly failing wafers suffer from an additional faster degradation mechanism which has a higher activation energy.

DOI:10.1049/ip-j.1985.0019

出版商:IEE    

年代:1985

数据来源: IET