Effect of the non-Lorentzian lineshape of semiconductor laser on a PSK coherent heterodyne optical receiver

In the letter the performances of a PSK synchronous heterodyne optical receiver are evaluated by taking into account the non-Lorentzian lineshape of semiconductor lasers by means of an analytical model.     

Balanced operation of a GaInAs/GaInAsP multiple-quantum-wellintegrated heterodyne receiver

The balanced operation of a multiple-quantum-well balanced heterodyne receiver photonic integrated circuit (PIC) is described. Using only SMA-connected 50 Ω commercial electronics, a free-space beam sensitivity of -42.3 dBm at 108 Mb/s and -39.7 dBm at 200 Mb/s for NRZ FSK (frequency-shift keying) reception has been achieved. This represents a 14 dB improvement over any previous heterodyne receiver PIC sensitivity. In addition to providing the multichannel benefits of heterodyne reception, this is also the highest sensitivity yet reported for any OEIC (optoelectronic integrated circuit) receiver     

Performance analysis of a noncoherently combined large apertureoptical heterodyne receiver

The performance of a noncoherently combined, multiple-mirror heterodyne receiver is analyzed. In the absence of atmospheric turbulence, the performance of the noncoherently combined receiver is shown to be inferior to that of a monolithic, diffraction-limited receiver with equivalent aperture area. when atmospheric turbulence is taken into consideration, however, the efficiency of a monolithic aperture heterodyne receiver, is limited by the phase coherence length of the atmosphere, and generally does not improve with increasing aperture size. In contrast, the performance of a noncoherently combined system improves with an increasing number of receivers. Consequently, given a fixed collecting area, the noncoherently combined system can offer a superior performance. The performance of the noncoherently combined heterodyne receiver is studied by analyzing the combining loss of the receiver SNR (signal-to-noise ratio). It is shown that, given a constant collecting area, the performance of the combined receiver is optimized when the diameter of each of the individual receivers is on the order of the phase coherence length r₀ of the atmospheric turbulence     

Frequency demodulation of a semiconductor laser by FM-AM conversion in an optical fiber

It is theoretically demonstrated that the FM light output of a semiconductor laser can be detected through FM-AM conversion using an optical fiber. The analysis is made in the case of narrow-band FM and for the fundamental mode in a step-index monomode fiber. It is shown that for a 10 GHz modulation frequency, the fiber length necessary to achieve maximum demodulation lies in the range of 10 km.     

Thermal emf in a bipolar semiconductor with phonon drag of carriers

An expression is derived for thermal emf in a semiconductor sample for small deviations of the carrier concentrations from the equilibrium values and an arbitrary extent of the phonon drag of electron-hole pairs. With thermal drag, the thermal emf changes substantially in a sample of arbitrary dimensions. Under certain conditions, the thermal emf sign may also change.     

Stabilisation of heterodyne receiver sensitivity with automatic polarisation control system

A low-insertion-loss automatic optical fibre polarisation control system with low driving voltage and low monitoring power has achieved stabilisation of the receiver sensitivity within the fluctuation range of less than 0.4 dB in an optical FSK heterodyne 280 Mbit/s, 141 km transmission experiment.     

大气相干长度及其对激光外差接收机的影响

本文计算了水平光程和倾斜光程上的大气相干长度与外差接收效率。结果表明大气湍流对水平光程上的光学外差接收机的影响很大，而在斜程上踹流的影响要小得多。文中还给出了某些情况下的极限天顶角。最后简单讨论了激光外差接收机的最佳接收口径．     

Investigation of a heterodyne receiver with open structure mixer at 324 GHz and 693 GHz

The performance of a submillimeter heterodyne receiver using an HCOOH laser local oscillator and an open structure mixer with a Schottky barrier diode has been optimized for 693 GHz. Working at room temperature a single sideband (SSB) system noise temperature of 7,300 K, a mixer noise temperature of 6,100 K and a conversion loss of 12 dB has been achieved. The same receiver system has been investigated at 324 GHz using an HCOOD laser local oscillator yielding a noise temperature of 3,100 K (SSB), a mixer noise temperature of 2,400 K (SSB) and a conversion loss of 10 dB (SSB). An acousto-optical spectrometer has also been constructed, with 1024 channels and a channel-bandwidth of 250 kHz. The system NEP per channel was 2.5×10^?17 W/Hz^1/2 at 324 GHz and 5.0×10^?17 W/Hz^1/2 at 693 GHz.     

5.1--Use of an oscillating laser as a heterodyne receiver preamplifier

In this paper the results of a study of the amplification characteristics of lasers for signals injected near their frequencies of oscillation are reported. An approximate theoretical treatment is given which indicates that substantial amplification will occur under conditions for which the anisotropy of the laser cavity is small, the polarization state of the injected signal is orthogonal to that of the primary oscillation, and the two signals are critically coupled. For like polarization of these signals, postive amplification occurs only for substantially reduced laser excitation or increased cavity loss. The experimental observations are in qualitative agreement with the theoretical predictions with gains as high as 600 having been observed for orthogonal polarizations near critical coupling. The optical bandwidth appears to be at least several MHz.     

Characteristics of a semiconductor laser pumped brillouin amplifier with electronically controlled bandwidth

We demonstrate the operation of a semiconductor laser pumped fiber Brillouin amplifier. An optical gain of 5.5 dB/mW of pump power is obtained. The 15-MHz intrinsic bandwidth of the amplifier was extended more than one order of magnitude by adding frequency modulation to the pump laser. Bit-error-rate receiver sensitivity measurements with an in-line Brillouin amplifier demonstrate a 16-dB improvement in the system gain at 10 Mbit/s and a 8.5-dB improvement at 90 Mbit/s. Noise calculations show that the amplifier has an excess noise factor of 50-500 depending on the amplifier length and pump power.     

Characteristics of InSb mixers and backward wave oscillators in a submm heterodyne receiver

In this paper some aspects of two of the most important components of a previously described submm heterodyne are discussed: the InSb mexer and the backward wave oscillator. The (known) properties of the InSb mixer and our method of fabrication will be briefly discussed. The aspect of matching this mixer to the waveguide is treated more extensively both in theory and practice. Finally the performance of InSb as a mixer at higher frequencies is briefly considered. Some properties of the backward wave oscillator which are of special relevance when using it in combination with an InSb mixer, have been measured and they are discussed in the last section.     

Some features of operation of a heterodyne receiver with the Mach-Zender diplexer in a wide wave region

The relations between the diplexer transmission coefficient, the noise suppression depth of a local oscillator and the path difference of an interferometer, maximum operating wavelength, intermediate frequency amplifier characteristics are considered.     

Basic performance of a direct conversion DECT receiver

The measured operating performance of a new incoherent direct-conversion receiver for high-data-rate mobile communication systems is presented. The results prove the suitability of such a receiver for the future digital European cordless telecommunication (DECT) standard.<>     

BER performance analysis of a direct conversion receiver

Direct conversion receivers are increasingly popular for use in mobile terminals. This is due to advantages over other architectures such as heterodyne receivers in terms of cost, electrical current, and physical size. However, a direct conversion receiver often generates a DC-offset that has to be taken care of either by suppressing the DC-offset in the radio-frequency part of the receiver, or by taking care of it during baseband processing. A theoretical analysis of the bit error rate (BER) performance in a direct conversion receiver with different levels of DC-offset suppression is presented. Explicit results are presented on how the BER depends on the signal-to-noise ratio (SNR), the signal-to-DC-level, and the choice of pilot symbols both with M-QAM and M-PSK in a slow, flat Rayleigh fading channel. A design rule, which applies to the design of DC-compensation in direct conversion receivers, is also presented     

Design of semiconductor laser with current-induced cooling

A novel design of semiconductor lasers and photodiodes with cooling by injection current is proposed. Carriers are injected into the active region via tunnelling with absorption of optical phonons. An expression for the optimal emitter lengths in a current-cooled system is obtained     

Frequency response and bandwidth of a spherical random array

Exact results for the expected frequency response of a spherical, sparse random array are determined, when focused at any point, including points within the sphere. Related bandwidth results are given.     

Fabrication of a heterodyne receiver OEIC with optimized integration process using three MOVPE growth steps only

An optimized integration process is reported requiring only three epitaxial growth steps for the fabrication of an OEIC encompassing a single-mode laser, a waveguide element, and fast photodiodes. The process was applied to the fabrication of a heterodyne receiver including a semi-insulating buried heterostructure (SIBH)-DFB-laser with an output power of 14 mW and a side-mode suppression ratio greater than 40 dB, a 3-dB coupler, and high-speed balanced photodiodes with a bandwidth of 9 GHz. The laser can also be used as a transmitter laser exhibiting a modulation bandwidth of 11 GHz.     

Subnanosecond wavelength-tunable heterodyne receiver and analysis of its fundamental switching speed

We experimentally demonstrate subnanosecond tunability of a heterodyne receiver employing a fast-switching local laser oscillator. A <0.7-ns switching time and the feasibility to achieve hitless switching are demonstrated. Theoretical analysis of the transition process indicates that switching time shorter than a single bit slot can be realized in a typical receiver configuration with a fast-switching local oscillator.     

Radiative lifetimes of electrons and holes in a thin semiconductor layer

Radiative lifetimes of nondegenerate electrons and holes distributed uniformly in a semiconductor layer either deposited on a substrate or bounded by two dielectric media are calculated. The obtained expression takes into account the radiation reabsorbtion and interference effects and determines the dependences of the radiative lifetimes on the refractive indices of the external media and on the layer thickness.